Indepth Equine Podiatry Symposium Notes Written and presented January 2010 by R.F. (Ric) Redden, DVM Much has been written about this small but very significant bone found in the heel area of the horse's foot. The term navicular disease sounds benign enough and many believe it to be a specific disease that is easily diagnosed. However, the contrary would be more exact. In spite of intense efforts by researchers, anatomists, pathologists, surgeons and diagnosticians, this area continues to hold many secrets. The syndrome itself is very complex as it involves not only the bone itself, but also adjacent support structures and anatomical zones that house or protect this very sensitive area. Therefore, diagnosing navicular disease is not straightforward and should never be approached with a black and white attitude. Many years ago it was thought that increased pain identified by hoof testers over the center frog across the heels, a positive response from a PD nerve block and a lollipop or two in the 65° DP radiograph was all that was needed for a navicular diagnosis. However, there are many horses with very significant appearing lesions that never develop soundness problems and remain competitive at high levels and others that have no demonstrable lesions but have chronic heel pain. Treating navicular disease can be just as confusing as diagnosing it. Often the coffin joints and/or bursa may be injected with hyaluronic acid and/or corticosterioids. The horse is then sent to the farrier, who is expected to provide a solution given only a very generic prescription: raise the heel and rocker the toe and/or apply an egg bar shoe with wedge. This can be a difficult task without a point of reference. Treatment can be further complicated if the horse is on a tough training schedule, and the owner, trainer, etc. are reluctant to rest him unless absolutely necessary. You must ask yourself, how can such a complex, mysterious syndrome have such a vague treatment plan? Examining the unique characteristics of each case and determining the mechanical needs of the foot in question, rather than the syndrome as a whole, can provide a host of treatment options that can set the stage for successful treatment and management of this syndrome, lifting some of the stigma that has long been attached to it. Examining the Foot Developing an astute eye for detail can help all concerned detect unique characteristics that can alert us to potential problems, prevent lameness issues and show the effect of chronic problems. When evaluating the exterior of the foot, avoid lumping all feet into the same category as other feet. As we well know, feet are not born equal and certainly don't remain in a static state. They are constantly changing due to growth, use, wear, trimming, shoeing and pathology. The unique characteristics of feet become more noticeable as you develop your eye for detail. Studying photos taken perpendicular to the subject is a great way to train your eye to see these characteristics. Radiographs taken in the same plane can help us tie the external characteristics with what is happening inside. Given time and keen focus, we can begin to see the imaginary radiograph as we look at the foot and vice versa. The basic points of interest that make feet appear different are hoof angle, growth rings and shape of the toe, quarters, heel and ground surface. There are several stereotype feet within all breeds with a large range of foot sizes, shapes and growth patterns. The majority of horses regardless of breed will have a high/low syndrome (one foot has a steeper hoof angle with more heel mass). Even though it can be very subtle, the highest profile foot will have characteristics of a low grade club foot. These small differences influence the overall health of the feet. Growth rings that are quite close together indicate slow growth. This may occur at the toe with club feet, the heel with the negative PA foot, the medial quarter for horses that naturally list to the medial quarter, etc. Wide growth rings indicate accelerated growth and can occur at the heel in club and laminitis feet and at the toe in negative PA feet. The amount of sole depth can greatly affect the way we evaluate and treat navicular cases, therefore it is important to note this important measurement and identify what category it falls under: 20-25mm: very thick 15-20mm: adequate 12-15mm: moderately thin 5-12mm: thin5mm or less: super thin Wall thickness goes along with the thickness and durability of the sole. The thinner the sole, the thinner and more fragile the wall and vice versa. Pastern alignment in the healthy foot will lie in the same plane as the face of the hoof wall. The club foot pastern sets forward on the hoof, which puts the linear face in the same plane as the hoof. The heel and buttress shape varies greatly depending on PA and foot mass. The club or upright foot has adequate to excessive heel mass, which creates a thicker, more durable appearing heel. The bar size, shape and overall strength is relative to hoof shape, PA and overall health of the foot. The frog plays a major role in protecting the heel structure, aiding circulation to the foot and acting as a major energy sink when healthy. Note the width, depth and length and compare it to the frog on the opposite foot. Seldom are they identical. The higher heel will normally have a smaller frog set well into the depths of the heel. It will be quite small compared to that on the opposite, lower profile foot. The crushed heel foot will normally have a large, thick frog that may be well below the crushed heel tubules. Observing these basic characteristics every time you look at a foot soon helps you develop an astute eye for detail. The success of any and all therapeutic shoeing protocols is relative to the amount of foot mass and PA that we have to work with. Farriers need radiographic information and an eye for external characteristics that indicate what is available for them to work with. Hoof Testers Use hoof testers carefully when diagnosing a foot problem. A tough, dry foot with good mass will be unresponsive even when brewing a full blown abscess. A soft but fragile foot with minimal mass will be responsive even when the only pathology present is lack of foot mass. Young training horses almost always test sore over the frog and across the heel, which is more often than not just part of training soreness. Stop and ask yourself just how many sensitive structures are being influenced by the testers. Hoof testers are great for quickly locating commonly occurring abscesses, but be careful how you read the response when using them routinely for generalized foot lameness. Radiographic Exam Radiographs are certainly indicated when navicular syndrome is suspected. The views you take are relative to the information you seek. I never rely on one view to confirm a lesion. If I can't see it on at least three views I am not satisfied it exists. Note that if you use a digital unit you may find it difficult to penetrate the navicular bone enough to read the trabecula pattern. I prefer traditional film with grid over the majority of digitals I have used as I can design my exposure any way I need it. Digital does not allow this flexibility and the resolution and detail of portable digital units does not meet the standard consistently attained with my traditional film/grid combination. Yes, you can enhance the digital image by adjusting the contrast, but only within the range of the unit's programming. This can be a disadvantage, especially when you need to shift either well below or above the pre-set range of penetration. Before referring to traditional film grid techniques as dinosaur technology, take a very close look at the lesion that can easily be demonstrated with a versatile technique that you most likely will never see with your digital unit. My preferred radiographic views for identifying navicular lesions are as follows: Lateral: When taking laterals for suspected navicular cases I use traditional medium speed film, asymmetric screens and 6:1 grid with high beam alignment centered over the navicular bone. If the wing of PIII has calcified well into the lateral cartilage it will be superimposed over the tendon surface of the navicular bone, obscuring the detail I seek. However, you don't know this unless you look. The tendon surface angle (TSA) is measured by drawing a line along the distal 1/2 of the navicular bone and connecting it with a line along the ground surface of the foot. It may be quite low, 10-15°, or extremely high, 35-45°. Concentrate on this area as most all navicular pathology occurs along the distal half of the bone and support ligaments. Being able to alter this angle offers a reliable means of managing the pain response. Using the lateral low beam radiograph, measure the TSA of the navicular bone. Use this angle as a guide when designing your shoeing protocol for reducing tendon tension. Also note bone angle, as it can vary greatly between horses and on the same horse. Flexed lateral: I take this view with a grid in the Redden Navicular Block™ and center the beam at the subject of interest. Make note of the TSA as it relates to the ground surface. When the tendon surface is perpendicular to the ground while positioned in a 65° DP block, the image produced will be a true DP representation of the bone. When the primary beam strikes the face of the navicular bone at a less than or more than 90° relationship with the ground, a large variety of images are produced. This gives rise to a large number of concepts and theories concerning radiographic lesions as there are few if any comparative views when the 65° DP is made without regard for the TSA. The image obtained will vary greatly simply due to a wide range of beam/subject positioning. Therefore by using the flexed lateral view we can observe the relationship of the primary beam to the navicular bone when the 65° DP view is produced. Cortical lesions and areas of calcification within the impar ligament can be described with this view. Remember to center the beam over the navicular bone to avoid image distortion. DP: The straight on DP high beam is my third view. This view requires high MAS and a grid to produce the optimum image. PII must be all but burned out to see the cortical and trabecula pattern of the navicular bone. If you do not see a lesion with hard penetration and grid on this view, it is not likely you will see it on any other. However, deep penetration is required and your digital most likely will not allow you to go there. You will get a very generic look at bone shape and only enough detail to visualize the larger, more notable lesions. 45° DP with grid: This view sets the wing of the navicular bone in relief and offers a nice view of lesions that may be located within the impar ligament. Once I have found lesions in the above mentioned views, I confirm them with the following views: 65° DP with high beam: This view will reveal lesions within the main body of the bone and associated ligaments. Note the TSA and how it lines up on the 65° flexed lateral view relative to the ground surface. This helps us better understand the way the image was made. This view can reveal very significant lesions, but it may fail to reveal large, thin layer cortical flaps that remain attached to the cortex. Shoes should always be pulled for this view as the branches of the shoe can obscure the wings of the navicular bone and cause unwarranted scatter radiation. Even aluminum shoes create significant scatter radiation and reduce resolution. The moisture content of the frog and buttress plays a major role in just how much you can see on this view. The hard, dry foot requires increased MAS to penetrate the deep structures and even then the resolution will not be as good as on the foot with higher moisture content. I trim the central frog sulci, creating a smooth surface. The deep, dry fissure will always be superimposed over the frog on the 65° DP view and can cause problems with interpretation. Get rid of the shadow with a farrier knife. I do not pack feet for the sake of getting rid of airspace created by the sulci of the frog. All feet have gas density associated with the frog and cup of foot. Therefore I prefer to read it, as I can actually see the anatomy that creates the gas density. When you pack the foot, resolution and detail suffer tremendously. Pack one side and see which has the better resolution. Tangential (or skyline) taken with grid: This view has been recommended for many years as a reliable means of seeing the tendon surface. Unfortunately this can be very misleading. Unless the TSA is 40° or better, this view with the foot sitting on a tunnel does not reveal the tendon surface, as it is well below the prominence that appears to be tendon surface but is actually the most proximal point of the central crest. Also, when the beam strikes the cassette at any angle other than 90° distortion is automatically part of the image. Therefore using the tunnel guarantees distortion. The farther from 90° the beam hits the cassette the more distortion is created. TSA of 40° or greater offers a better view of the actual tendon surface than the lower TSA that is frequently found with the lower profile foot. The skyline tunnel view of the low TSA and bone is not representative of the tendon surface and the bone is grossly distorted due to the oblique beam angle. Yes, a few lesions in the DDF and along the proximal aspect of the navicular bone can be identified as well as a few lucent lesions superimposed over the bone, but all are distorted when the beam strikes the cassette at an angle less than 90°. The sclerotic cortex and pre-navicular cortex that is often diagnosed is most often the product of distortion and can be misleading and result in gross misinterpretation. 45° 65° DP: When taken with a 6:1 grid This view can be helpful to describe location, size and significance of smaller lesions as well as those found in adjacent tissue. Magnification will occur as the plate is approximately 4-5 inches from the bone itself. The gold standard when using traditional film and a 6:1 grid is to strive to take all film with a perpendicular beam/film relationship. Center the beam on the subject of interest, use adequate KV and MAS to penetrate the bone and optimum resolution and detail can be obtained. Management I like to think we are managing navicular disease instead of treating it. Normally speaking, navicular disease can't be cured, but the painful tissue can heal given the proper environment and the horse can most often be useful once again. Squaring or rockering the toe, raising the heel and applying an egg bar shoe remains the prescription for most farriers. There is some merit in this very vague description of how the horse should be shod, as some will respond favorably and continue doing their work for a while. However, the tough, non-responsive cases require more mechanics (less DDF tension). In order to design a more detailed, specific treatment plan, both vets and farriers should ponder these questions: Where is the pain? When is it painful? What part of the mechanical formula within the foot is no longer in harmony? Let's assume the pain occurs as the DDF tightens along the inflamed bursa and bone during peak load. Reasons for pain may include a cyst that has suddenly become painful, a cortical surface ulcer, collapsed cortex and extensive abrasions to the tendon as it courses over the rough surface. Fractures of the navicular bone are relatively rare compared to more commonly occurring lesions, but they do occur, as do congenital bi and tripartite navicular bones. Any one or all of the above can be associated with a routine run of the mill case. Horses experiencing pain associated with the navicular bone and support ligaments prefer not to drop their heel during peak load regardless of what lesion is causing the pain. Watch closely and you can see this compensated travel pattern. Some will actually jog sounder on a hard surface than they will on a very soft one, as the heel sinks into the ground on a soft surface, increasing DDF tension and therefore pain. Soft tissue parameters also need to be considered as they influence our management protocol. The farrier needs to know sole depth, PA, extent of the damage and whether rest is recommended or the horse is to continue light training. All of these factors influence how the horse should be shod so that everyone is happy. The DP and lateral low beam views will reveal how much sole depth we have to work with as well as heel mass and medial/lateral balance. The horse with 20mm of sole and a 3 to 5° PA has options not available to horses with 10mm of sole and a negative 5° PA. If the horse can be shut down (no training) for at least 6-10 weeks, the shoeing protocol will be totally different than the one we would elect for a horse that remains in training. The Rocker Rail Shoe The extent and chronicity of the lesion may require moderate to drastic DDF tension release to relieve the hot spot. I like to think of it as simply removing the idle pulley effect of the navicular bone, which has a primary function of reducing stress to the tendon and articular surface of the digits. This can be done with a self-adjusting PA rocker rail shoe that raises PA several degrees. This shoe has potential to drastically reduce friction from the tendon as it glides over the bone. How much raise is needed is relative to the existing PA, TSA and level of pain associated with the lesion or combination of lesions. The goal is to enhance the healing environment by reducing the overall friction reducing function of the navicular bone. This certainly does not cure the problem as the lesion remains and may become increasingly worse, but it can remove a large majority of the pain by drastically reducing the tendon force causing the hot spot. The inflamed tissue can heal as long as it is not being continually traumatized. The horse with very small navicular changes that is off and on lame and seldom shows more than grade 2 lameness on a tight circle may require a much smaller PA increase and can often go in a full rocker shoe that only raises the PA 3-5°. When that is all that is needed there is no reason to go for the overkill mechanics. You may need that level of mechanics later if the lesion is progressive. The horse can often go back into competitive training following a few weeks of healing as long as the mechanics of the shoe maintain a happy balance between healing and preventing further damage to sensitive tissue. While there are rare cases with large lesions that show no evidence of pain, most feet with large, distinct lesions will routinely be quite lame. As a rule I put these cases in a rocker rail shoe that allows the horse to establish a 15-18° PA. Turnout and slow trail riding is indicated as soon as the horse is comfortable. Often the pain response is minimal within a few days, even with horses that have been reported lame for many months to years. Daily slow exercise appears to be beneficial as the soft tissue is healing. The high scale case that becomes quite sound with 4-6 weeks of rest can be reset and begin a slow exercise program after the second reset. Many of these cases will remain quite sound in the rocker rail and remain in it when they go back into full training. From barrel racers to pleasure or halter horses, the mechanics of the shoe have not been a problem. Often owners and trainers want to know when the horse can go back into a flat shoe. Stop to think about this. As long as the lesion is there, putting the navicular bone back into a high tension mode will soon start the entire process over once again. This horse has osseous changes associated with the extensor process and distal PII, as well as navicular lesions. The rocker shoe satisfied the mechanical demands for both problems, relieving the tension of the DDF across the navicular bone and reducing the pinch effect of the lesion at the coronary band, as the shoe prevents overextension. Note the parallel line between the wings of PIII and the heel branch of the shoe. The foot side of the heel branches has been forged to reduce pressure on the tender heel buttress. Shoe Application Care is due when trimming and applying the shoe. The positive PA foot needs to have the heel pushed back slightly, starting at the widest point of the foot. The goal is to create a parallel surface between the heel tubules and wings of PIII, all the while maintaining 20+mm of mass between these two planes. This is an important aspect to the mechanics as it increases the length of the heel load zone. Even though heel load is increased, the tension over the navicular bone is significantly decreased. There is a very distinct landmark at the junction of the skin and frog just proximal to the central sulci of the frog. Passing an imaginary line through the point of the apex of the frog can give you a very good idea of what the PA is. Put a dot of paste on the little area that protrudes at this junction when taking lateral radiographs and observe the relationship. Farriers use this imaginary line to find the plane of the PA. Of course you don't rasp down to this line, as you would be out of foot and into the pink, but use this plane for all rockered shoes. In most feet there is very little hoof that comes off when setting a foot up for a rocker. Rocker the toe forward of the apex, being careful not to involve the sole directly beneath the apex. Then forge the rocker into the rail shoe with breakover well behind the center of the shoe. Start forging from the heel of the shoe and work forward. Using a rocker jig is helpful for creating a nice, uniform radius on the ground surface. It is desirable to have the pivot point or center of the belly directly beneath the center of articulation of PII. Look at PII as if it was a wheel and PIII rotates around this axis. Then think of the belly of the shoe as a pivot point that allows the PA to rock forward. As this occurs, the coffin joint flexes around the center of articulation and the PA and TSA increase. On the low heel foot this pivot point should be slightly behind the widest point of the foot on the club or higher heel slightly forward of the widest point. Note center of articulation and the path that PIII travels, all due to the pull from the DDF. Getting the breakover too far forward forces the foot to tip back towards the heel. This is not good, and I see it far too often. The foot must rock forward of center balance to meet the requirements of reducing tension over the bursa and navicular bone. I normally clip my rocker rails whether glued on or nailed; this is just my preference. Glue vs. nails: Glue: When there is minimal foot mass, less than 15mm of sole and a low PA there is very little foot that can come off. Therefore, just rub the heel to create a horizontal plane and touch the toe ever so slightly, just a millimeter or two. Rocker the shoe and set it in a bed of Equilox® or similar composite. After the first six weeks there will be plenty of foot to nail for the next shoeing. Nails: When nailing the shoe there may be a 1/16 to 1/8 inch gap between the shoe and foot in the center of the belly. This is not a problem. The shoe should sit square and solid on the two front pillars and the heels. A small air gap should be observed between the toe and shoe before nailing. The gap under the belly will soon fill with horn and sole. You can fill this gap with composite if desired, but it is not necessary. You may need to weld a frog pressure bar in the rocker rail to prevent frog sag and further tubule crush on the low heel foot. If so, keep the frog as dry and tough as possible as it will just flatten out and compress when loaded. This foot will gain a lot of sole but little if any heel mass due to previously crushed heel tubules and crushed digital cushion. I seldom have to put a positive bar on the club foot as the frog is normally well recessed into the foot. The positive bar is technique sensitive and must be carefully fitted with each reset. Note this horse has a slightly positive PA but a severely broken back hoof axis, which is due to heel pain diagnosed radiographically with significant navicular lesions seen in several views. The upright pastern is a response to heel pain and not the low PA. Note the immediate improvement in digital alignment, which is the result of reduced heel pain. Fabricating the Positive Frog Bar I prefer to trim the foot, rocker the shoe, fit the bar tightly in the shoe. Set the shoe on the foot so the bar sits on the posterior half of the frog and the heels of the shoe are approximately 1/16 to 1/8 inch off the heel tubules. Lift it off carefully and weld the bar in place. Soften the foot side heels of the shoe and set it on the foot while in the welding heat to make sure the bar did not move out of the desired position. Positive frog pressure bar. When this shoe is applied, there should be a 1/16 to 1/8 inch gap between the heel tubules and the heel of the shoe. As load goes on the shoe, positive pressure is applied to the frog and buttress. Clip the shoes and then cool. Put two nails in and set the foot down, observing the heels as they slowly descend to just touch the shoe surface. If the horse objects to the pressure, pull the shoe, reduce the gap and reapply until he likes it. This shoeing protocol has been a tremendous asset for treating a lot of heel pain cases as it stimulates accelerated foot growth and minimizes the crushing action of the higher PA. Nerving Years ago we nerved everything that was unresponsive to medication. Most of us have found that the downside of nerving demands a lot of respect. There is increased risk of an abscess going undetected for several days to weeks, as the sole and heel are basically numb. Fulmagating abscesses can quickly become life threatening and are a major concern. Routine shoeing has inherent risk of an undetected hot nail, and thrown shoes or puncture wounds are a real threat to horses that are turned out. Think long and hard about nerving a navicular horse. There are better, more reliable and less risky options. When nerving works it is great, but if it goes sour you can be left with a major cripple and possibly a horse that must be euthanized. Avulsion of the DDF When the tendon surface lesions or craters are large and have eaten into the tendon, the DDF actively grows into the defect and becomes traumatized with each step, inherently weakening the tendon. Nerve this foot and the tendon can sustain irreparable damage. All of the sudden the toe will turn up and the horse will have an odd shaped heel/pastern profile. This presents the client with a life long problem that can be managed but never goes away. Avulsion of the tendon can also be due to excessive trauma to the heel subsequent to long term nerve blocks, such as absolute alcohol and cryo nerving. Quarter Horses and Navicular Having seen many breeds over the past 35 years, I find quarter horse to be far more prone to navicular problems that appear to originate within the bone itself. The quarter horse stereotype varies to some degree, but as a rule their feet are quite small relative to bone and body size. I often see 1,200 to 1,500 pound horses wearing a 000 shoe, which means the foot is less than four inches wide. The majority of the breed will have upright hoof confirmation with tight heels and a small frog that sits well up in the foot. The tendon surface angle (TSA) of the navicular bone is usually quite high, 30-45°, and the PA can be as high as 15°. This describes a low to mid scale club foot. The shape of the navicular bone is also quite small and appears to have a thinner cortex than that found on horses with lower PA and TSA. The steeper TSA apparently does not receive pressure from the DDF as would be expected with a lower TSA and PA. This could be the reason why the navicular bone does not appear to be as strong and mature as it is in feet with a lower TSA. Possibly there is a correlation as the incidence of navicular lesions and clinical signs appear to be much greater with this type of foot than with the low heel and crushed cushion with negative PA.

2001 - 14th Annual Bluegrass Laminitis Symposium Notes The Wild Horse's Foot Written and presented January 2001 by R.F. (Ric) Redden, DVM (If you would like to learn about adopting a wild horse or burro, click here.) I envied individuals who had the opportunity to study the feet of wild horses. So in January 2000, I launched a very serious project designed to record the radiographic and gross anatomical data in regard to wild horse feet. Project goals: 1. Determine if wild horse foals and weanlings develop PIII fractures along the parietal groove that are frequently found inlight breed domestic horses, especially Thoroughbred foals. 2. Develop a range of normal radiographic parameters; horn-lamellar zone, toe - heel angles, sole depth, palmar angle, relationship of the extensor process with the top of the hoof wall and digital breakover. 3. Record the incidence of club feet (all grades) in young and mature horses. 4. Establish a range of normal contrast pattern in the digit using a venogram. 5. Collect a significant number of foot molds for further study. 6. Record angular deformities. To my knowledge there has been only one radiographic study on live wild horses. (ref. accomplished with a turn table chute). The first group of horses was gathered just south of Las Vegas four days prior to my examination. Using Ketamine and Rompun to sedate the horses, foot molds were obtained and radiographs taken. Views include lateral, AP, and 65 degree DP views. With the assistance of Dr. Tom Hartgrove and the Bureau of Land Management, we were able to study eight individual cases. All were more than one year old, no pathological lesions were observed, and none presented with club feet or abnormal angular deformities. All were in good flesh, but they appeared thin compared to domestic standards. Regardless, they all seemed healthy and sound, with a superb protective attitude. The following is a basic summary of the radiographic soft-tissue parameters: 1. Horn - lamellar zone range (20/20 mm. - 25/25 mm., majority 25/25 mm.). 2. Sole depth (15 mm. average). 3. Palmar angle (zero degrees). 4. Digital breakover distance (zero to 10 mm.). 5. Extensor process/top of hoof wall (ranged from zero to 10 mm.). 6. Toe angles (range 50 to 59 degrees, average 55 degrees). 7. Heel tubule angle (40 degrees). 8. Toe length (hair to breakover) (range 2 to 2 1/2 inches, average 2 1/4). 9. Horn height in the center of the foot (1 1/2 to 2 inches, average 1 3/4 inch). 10. Foot size (3 3/4 x 4 W/L 4 1/2 x 5). NOTES OF INTEREST: This was a moving experience to say the least. Being the first to ever touch the feet of this small herd and to feel the strong message of Mother Nature was very enlightening and a catalyst for my project. I was surprised to find very short hoof capsules, yet all had thick, protective soles. The soles appeared burnished and fused with the frog which was hardly noticeable. There was only a slight mention of a medial - lateral sulcus. The characteristic shape and size of PIII varies considerably from that of most domestic horses. The apex is more blunt and the solar surface is more convex along the wings as viewed from the lateral radiographs. It is smaller in relation to hoof size than seen with the domestic horse. The palmar angles are basically zero degrees verses three-five degrees for front feet and five to eight degrees for hind feet (ref. Verschooten). The horn - lamellar zones measured 25 mm on most mature horses verses 15 mm for the light breed domestic horse. The endodermal/ectodermal junction measured 7.5 mm from the face of the bone. The horn - lamellar zone was 1 - 1 with all young feet, only those three years or older exhibited the thicker wall characteristics. The front and rear feet all exhibited a similar breakover/heel-load surface. The wall along the ground surface had a very smooth radius that was void of any sharp edges. All feet were worn smooth with no signs of weak walls or broken out horn. January 11, 2000 Second herd consisting of 1500 horses. This was simply a drive through and walk through examination. This herd contained 600 yearlings and five newborn foals, with the balance being older horses. Radiographs, venograms, photos, and foot molds taken on 22 cases consisting of: Two mature mares with foals. One foal Seven mature horses. Twelve yearlings Some of these cases had been in captivity 30 to 45 days prior to examination. Noticeable hoof growth and pattern changes were evident in all cases held 30 days or longer. Assistance was provided by Dr. Joe Coli, the Bureau of Land Management at Palomino Valley, Jim Stewart, Bernard Pelletier, and John Sligh. NOTES OF INTEREST: All feet exhibited a similar breakover/heel-load pattern even when showing signs of excessive growth. Venograms were more difficult to inject than domestic feet as the intravascular pressure seemed much greater, regardless of age. Flow patterns were similar to the domestic horse but there appeared to be a smaller number of vessels. All revealed a significant reduction of contrast volume, as well as the number of vessels. No club feet were observed in the entire herd, but two yearlings had very upright pasterns in the rear. These cases were on their toes with their heels off the ground. They also presented with very tight, contracted heels. No varus deformities presented. Valgus deformities when present were seen as low grade 1/5. There were no PIII parietal groove fractures in the yearlings examined. Six feet had a grain size lesion in the area where the parietal fracture occurs in light breeds. Bureau of Land Management reported that they would see a few abscessed feet following a tough gather that required the horses to travel long distances over rough terrain. This would also cause an occasional stone puncture to the sole. All horses were gathered by helicopter and trailered to the holding center. NOTES OF INTEREST: Foals use their long tattered mane as a means of direct communication. The typical mouthing exhibited in all foals appears to be a direct line of communication. The large hair balls hanging off the shoulders of the mares was a security blanket for these babies. When the mares were anesthetized the foals stood absolutely still and made no noise even though they could not see their mothers. Mares with foals were thin but bagged up well. All vulvas were in a perpendicular plane to the ground. None dropped over the pelvic brim regardless of age or weight. This was very interesting as most domestic mares soon lose tone and have to be sutured. Mares had week old foals by their side, January 11, 2000. One foal was born the night before I arrived and was found dead the following morning. Examining the feet of this foal I was surprised to find no feather, but it had a well-formed sole, frog and wall in less than 24 hours. The typical feather seen in domestic foals for several days after birth would make these wild foals more vulnerable to predators. How has this genetic change occurred? We need to know. I adopted three yearlings and shipped them to my farm for further examination. July, 2000 Third Herd, Tonopah, Nevada: Approximately 250 horses were gathered, sexed, aged and culled for adoption, 47 foals that were eligible for adoption were taken from their mares; some were as young as a few weeks old. The very young ones were taken to a volunteer nursery for bottle and bucket feeding. This heard consisted of approximately 35 stallions, 47 foals, and 30 to 40 yearlings. The balance of the herd was mares. Observation: Most mares were 20 years old or more. The majority had foals or were showing signs of pregnancy. Most lactating mares were ribby but bagged up well. There is more grass growing on the paper I am writing this report on than can be found on 100 acres of their natural habitat. The older mares develop weak suspensories behind, a very straight hock and a steep, bull nose foot. With more in-depth study, the approximate age can be determined by simply observing the hind limb conformation. No sloping, tipped forward vulvas were noted. No true club feet nor varus deformities. Several chronic foot injuries were noted, and they appeared to be old lacerations. A few presented with blown out scars along the bulb of the heel from apparent abscesses. Approximately 35 stallions were in the herd. They were tough guys, excellent body condition, extremely durable, and ready to fight at the drop of a hat. Only the most dominant stallions were free of multiple war scars. Forty-five foals were closely examined. Front and hind feet were radiographed and several foot molds were made. No parietal groove fractures were found. No club feet. One foal was contracted behind with his heels well off the ground. One other foal developed severe hind limb contraction several weeks after arriving at the nursery. The very young foals, one week to 90 days old, were relatively easy to handle, but they were very protective. They were radiographed in lateral incumbency using .2cc Dormosedan, I.V. The older foals were typical of Thoroughbred foals that get little or no handling. All were examined using Ketamine and Rompun. What does the normal, mature foot look like and what can it tell us? Studying approximately 1,800 head, many very closely, one would like to think this would be representative of the natural foot. The range of norm was much larger than I expected to find. What influence do genetics and environment play with these feet? Does natural selection eliminate the club feet, varus deformities and other angular problems often seen with domestic horses? If so, how does this work? Are the weak and crippled culled by coyotes and mountain lions or simply starve? We do not know at this time. One stallion, approximately 20 years old, that was gathered in the mountains north of Vegas presented with front feet that are miles off the scale from what we consider balanced. However, he led the herd as the helicopter pushed them several miles to the trap. Sound and full of himself, exhibiting only a few battle scars, he was apparently a dominant sire for his herd of mares. Apparently this was a congenital deformity, so why wasn’t it self-limiting? Why wasn’t it seen in any other horses? Were the offspring victims of natural selection? Observations by Dr. Tom Hartgrove: 1. A three to four year old mare gathered a few years ago presented with a rye mouth. The mandible (lower jaw) was 90 degrees to the maxilla (top jaw). She apparently learned to eat foliage with her tongue. What foliage? They must travel miles to get a mouth full, but she survived. 2. Metacarpus and distal phalangeal fracture found on a two year old radiographed by Dr. Tom Hartgrove. How did this one survive? Dr. Hartgrove has examined foals, weanlings and yearlings with severe angular deformities and flexor contraction that have survived the funnel of natural selection in spite of their afflictions. 3. An aged stallion presented with a severe varus deformity of his left front pastern and foot. It took three fresh horses to catch him. He was adopted, castrated and broke to ride but became lame once he was shod with a therapeutic shoe. What has my preliminary study taught me that I can pass to you? We have much to learn from these horses. Yes, they are as natural as one could ever expect to find and live their entire life without man’s influence. There was a relative range of “normal”, but it was quite broad. There were also very distinct characteristics and conformation unique to the gather area. All were gathered from semi mountainous, desert terrain. Yet there are individuals that fall well outside the relative normal prototype that must be considered natural as well. They defy modern day standards and are standouts in their own population but they are natural, alive, quite healthy in spite of being tested by the harshness of their environment. They are groomed by the wind and trimmed by the abrasive surface they travel on. Previous work by Dr. Hartgrove confirms they have few, if any parasites, and appear to have a foal every year in spite of being aged (20 years plus). The typical wear pattern has a strong message. What is it? Does it mean we should make domestic feet look like the wild foot? I don’t think so. To do so would be disastrous. The domestic horse cannot survive with this length hoof capsule, and the majority of domestic soles are not genetically capable of ever being as tough as the wild horse soles given the same anatomical thickness. Apparently the environment plays a major role with the typical wild foot image, but genetics must also be a strong influence. I cannot help but ask, “Where did the club foot go?” I have looked at approximately 1,800 wild horses and not found one club foot that falls into the 1 through 4 grading scale I use for the domestic horse. The Bureau of Land Management at Palomino Valley reported seeing several club feet from a particular herd but agreed they are quite rare. We cannot look at 1,800 Thoroughbred, Arab or other light breed horses and say the same. The absence of varus deformities is also very interesting. Being a full time podiatrist for twenty plus years I have seen a steady rise in varus deformities among Thoroughbred foals worldwide over the past ten to fifteen years. This increase appears to inversely proportional to the ever growing knowledge bank concerning herd health. The more we learn about nutrition the faster they grow and the angular problems abound. Are we doing too good a job raising foals, are we overriding Mother Nature’s plan? I think possibly so. One of my adopted fillies, now a two year old, showed no signs of being toed-in (varus) until I started feeding her. Now she has changed her entire front limb stance. One thing is for certain, they are genetically designed to survive without the influence of man, and they do so with fewer problems. Knowing this assures me that we can learn from them and do a better job. I have asked, “How can a multimillion dollar race horse or sport horse live under immaculate conditions, in straw up to their bellies, with a full time attendant, veterinarian, and farrier, and still have a bruised foot on the day they need to beat the world?” I feel the answer is simple. Many of these horses’ feet have lost their natural ability to heal. As farriers and veterinarians, we can only eliminate the handicaps that prevent or delay the natural healing response. We cannot make them heal. Tissue heals and repairs at a programmed rate. I don’t think we can increase this rate; I think we can only reduce it. The self-healing protocol is enhance by the natural wear pattern. Using the four-point concept as a tool to eliminate known handicaps that delay healing has been a serious step forward for me. My version of the four-point concept leaves a foot with similar anatomical characteristics but with striking contrasts, too. We must be careful when comparing the domestic foot to the wild horse’s foot, as they are quite different in many ways. The gross anatomy, circulation, size and shape of PIII, location of PIII within the capsule and soft tissue parameters all vary greatly from those found with domestic breeds. My unique version of the four-point trim is not designed to make the domestic foot look like those described in this paper, it is merely a tool that helps us enhance the healing mode of the foot. The wild horse foot is a great study model but develops and matures under the beat of a different drummer. We must never forget that, and we must be careful extrapolating information from the natural occurring foot to the domestic foot. We also must remember that routine problems seen in domestic feet seldom are seen with the feral horse. At this time we do not have an accurate tracking system for the feral horse and do not know how many fall through the cracks. The stimulating message is that we can do a better job preventing common foot problems and aid recovery by simply enhancing the healing environment. Our best bred horses have poor quality feet only because we have not eliminated the handicaps suppressing natural healing. I adopted three yearlings that arrived in Kentucky in April. All were radiographed, venograms were performed and foot molds taken in Reno. A series of photographs described the growth and break up pattern of the two fillies and one colt. The colt had odd valgus deformities in both rear feet, and the medial walls were well under the normal load zones. Once the feet grew quite long, the condition corrected itself. The light boned black filly’s feet broke back weeks before the white foot of the roan filly and remains quite uniform and well shaped months later. The colt grew very long toes and broke back quite slowly months after the fillies. The front feet remained well shaped and relatively short, while the rear feet grew quite long toes and broke back at a longer length. Wear is very important. These yearlings lived in relatively dry conditions in Kentucky this summer, but their activity in three acre paddocks does not produce enough wear. The wild horses I have observed will travel many miles twice a day for water or food, which creates a very efficient self wear program. What is to be learned? We have just touched the tip of the iceberg. Are these tough, well shaped feet a reflection of environment or genetics or a combination of both? When does the young horse develop the double thick wall? Apparently it can revert back to a thin wall once domesticated. I examined two aged geldings that had been adopted for five to seven years. They had big strong feet but 15/15 mm horn-lamellar zones. My three cases will hopefully help us better understand this phenomenon. If the thicker wall develops, can it pass to offspring when bred to poor footed domestic horses? I hope to learn this. What is the major energy sink or pump of the foot? I think it is safe to say it is not the frog as we have been taught (ref. Dr. Robert Bowker). The lateral or ungual cartilage may play a major role, but it is my hypothesis that it is the laminae and sole corium that moves large volumes of blood, via action of the deep flexor tendon. With every step, heat and energy that would ultimately destroy the integrity of all feet is dissipated. Studying the effects of the deep flexor with various pathological as well as apparently normal feet I hypothesize that the secret of equilibrium rests in the function of the tendon. Further research is needed concerning the complex function of the flexor sling that ultimately controls the health of the foot. 📷 Related Article - How To Treat Club Feet & Closely Related Deep Flexor Contraction

2002 - 15th Annual Bluegrass Laminitis Symposium Notes Interpreting Soft Tissue Parameters and Lesions - The Influence of Trimming and Shoeing the Normal and Pathological Foot Written and presented January 2002 by R.F. (Ric) Redden, DVM Developing a detailed, methodical radiographic protocol is the first step in learning the healthy range of soft-tissue parameters of the equine foot, in addition to the commonly found soft-tissue image variations. Radiography should be considered a discovery exercise, as we are seeking information that will confirm, aid in the diagnosis of pathology or reveal parameters or lesions that may suggest a diagnosis. Farriers need DP and true lateral views to fully assess anterior-posterior balance, medial-lateral balance, sole depth and the palmar angle. Simple imbalance can lead to soreness and lameness that can be quickly alleviated with therapeutic trimming and shoeing. This information allows farriers to assist the attending veterinarian with a large variety of foot problems. Knowing your equipment and how to get the most from it allows the radiologist to make finite adjustments that meet the demands of the exam. The Lateral View In order to take a true lateral radiograph, the primary beam should be centered 3/4 to 1 inch over the positioning block or at the level of palmar surface of PIII. The true lateral will offer information on sole depth, HL zone, CE, palmar angle and digital breakover. Sole depth Sole depth is measured from the apex of PIII to the ground surface. Breed and other factors influence the depth of the sole. Centering the beam close to the palmar surface offers accurate measurement of the distance between the palmar surface of the shoe or ground surface. Your positioning block also needs an opaque marker (wire embedded in the face of the block works well). This marker clearly reveals the ground surface of unshod feet. The shoe becomes the marker for all shod horses. When taking a true lateral radiograph, notice that the film will have the branches of the shoe superimposed; therefore, you will only see one branch of the shoe. The barefoot horse will seldom have air density between the sole and the opaque marker, as the sole is a natural load bearing surface. Often though the shod horse will have air dense space between the sole and the foot surface of the shoe. This space is present for several reasons, each of which is considered vital to full assessment. Strong feet with adequate mass and ideal conformation have a natural cup that often produces a large air space between sole and shoe. Trimming the feet also greatly influences the sole depth and cup of sole. When comparing changes in progressive film, it is necessary that the film be comparative. Measuring the sole depth on every lateral film will help you develop an eye for the range of normal or at least what you normally find on the feet you examine. There is a difference. Like all other parameters, if you only measure the pathological cases the range of normal will escape you, diminishing your ability to distinguish subtle pathological lesions. Mature five inch feet on most light breed horses will have a sole depth of 15-20 mm. Fifteen millimeters is the minimum depth. Venogram studies on many sound feet with good conformation indicate that the sole corium normally occupies approximately 10-12 mm of the solar depth. The concave surface of the sole and/or coffin bone is not visible on the lateral projection; therefore we are seeing the depth of sole directly beneath the perimeter of PIII. Less than 15 mm of sole depth is considered inside the comfort zone, as there is not adequate room for the normal circulatory solar plexus. Race horses and event horses that often have 10 mm or less are generally foot sore horses with collapsed heels and extremely thin walls. Regardless of the concomitant pathology, their feet are severely compromised on a good day. Sever lack of foot mass is the primary diagnosis. Excessive wear can be a contributing factor for thin-soled, barefoot horses, while unshod horses that paw continuously when tied can quickly remove several millimeters of sole and toe. This wear pattern will be obvious to the trained eye. I use my film to confirm a diagnosis, while including evidence found through a thorough physical exam relative to the history. White line disease and other common problems certainly have pathognomonic lesions, but a good history and even better exam will often become quite valuable. The acute stage of laminitis can be more difficult to diagnosis and assess due to similar pain-producing syndromes; therefore, astute attention is required when examining the foot, the film and the history. Baseline film made prior to your examination can be invaluable especially if positioning and film detail are relatively comparative. Pre-purchase film taken months before can be invaluable, but keep in mind that the purpose of the pre-purchase exam may have been quite different than yours. Beam positioning and detail may vary considerably forcing you to read between the lines. Comparative films are just that, they have identical positioning and detail. I like to first identify beam location and make a written note of the dissimilarities concerning detail and content then pass my opinion concerning the similarities. Having a very strict, personal protocol offers me significant advantages for all comparative films. Horn-Lamellar Zone (HL) Horn-Lamellar zone is one of the most valuable parameters for assessing lamellar and horn health. This zone is greatly influenced by beam positioning. To alleviate distortion, a consistent, perpendicular beam-film relationship must exist and be centered at the area of greatest interest. I like my primary beam to strike the foot at the approximate level of the palmar surface. This offers accurate measure of the depth of sole, thickness of the lower HL zone, and palmar angle. The upper HL zone is slightly distorted, but with consistent positioning this distortion remains constant. Most light breed horses will have an HL zone measuring 15 mm. When taking this measurement, I use two points of reference: the area just beneath the extensor process and the apex of the coffin bone, measured perpendicular to the wall marker (opaque paste). Exceptions to the normal 15mm HL zone include Standardbreds that generally measure 18-20 mm. Aged, heavy Thoroughbred brood stock and stallions will often measure 20 mm or more. Warmbloods and others with 5 inch wide feet will also range from 20- 22 mm. Most often the front and hind feet will be very similar, within 1-2 mm. Weanlings and yearlings will vary greatly depending on their stage of development. Normally the upper measurement will be greater than the lower by 1-2 mm. Adult horses that have had their toe backed up hard will have a smaller zone at the apex. Radiographically, there is a striking difference on a backed up toe. The opaque zone seen on the radiograph delineates the junction of sensitive and non-sensitive laminae. It also clearly reveals lamellar thickness within the lamellar space, in addition to horn depth. This normal soft tissue structure is an invaluable aid when distinguishing rotational changes that have occurred within the horn wall (e.g. white line disease and occasional club foot) verses capsular rotation that occurs due to laminitis. Law suites often hinge on which side of the zone is beyond the range of normal. Subsequent films taken after your baseline views may reveal subtle but significant swelling of this zone. With laminitis these changes are very significant and often can be visualized long before other more obvious signs of rotation and/or distal displacement have occurred. Clinical cases that have 10 mm of acute lamellar swelling as a rule have a grave prognosis. Success with these cases is dependent on swift reperfusion of the digit. Chronic thickening of the lamellar zone must not be confused with acute swelling seen in acute cases. These are two totally different problems often can only be distinguished with a venogram. Palmar Angle This angle is measured by drawing lines along the palmar surface of the wings of PIII and the ground surface. The angle where these two lines intersect is the palmar angle. I measure at the wings because they better represent the body of the bone, and represent the area of the digit designed to carry load and absorb tremendous energy. The palmar surface at the apex is often in a more proximal plane. In addition, the sharp, fragile border of the apex is often distorted due to pathological conditions that cause excessive loading and trauma. Bending or lysing can be found with club feet, laminitis, white line disease, flat, shallow feet and a variety of flexor deformities. Measuring the angles can be arbitrary and non-specific as there is seldom a straight line to follow. I am concerned with large increments of angle change; 5-10 degrees or15-20 degrees, as smaller more detailed changes are difficult to measure and do not add to the big picture. As a farrier, I use this angle to help design all therapeutic shoes. This angle can range from a negative 10 degrees (severe caudal rotation), which is frequently found in rear feet with very steep coronary band angles, to 45 degrees in severely rotated, chronic laminitic cases. Ponies and other breeds with very upright hoof capsules often have relatively thick soles with deep cups. These feet may be 15-20 degrees in their normal state. Coupling the palmar angle with sole depth and HL zones, we can find a direct correlation to the events that precede many pathological conditions. Pathological conditions that involve the apex, anterior lamellar zone and horn wall can be treated successfully by shifting load away from diseased areas to the healthier heel zone. I often use the palmar angle to facilitate this mechanical advantage. Utilizing the simple mechanical shift of load enhances the healing environment and diminishes the painful response. This offers the podiatry team a meaningful, reliable means of treating a variety of foot ailments. The normal palmar angle is certainly not written in stone, as it varies considerably among breeds as well as within breeds due to unique characteristics of foot conformation, environment, training demands, etc. As a rule, light breed horses with acceptable, sound hoof conformation will have a natural 3-5 degree palmar angle in the front and slightly higher in the hind feet. The coffin bone angle is normally 50-51 degrees in most feet . The exception are club feet and extremely low angle hoof capsules. These feet will have a hoof angle somewhere between 53-56 degrees. This is not a standard, just a reflection of a collection of commonly found normal feet. Mustangs that I have radiographed in northern Nevada were quite flat and void of a palmar angle. A stark difference can be found with the internal structures of these feet verses the domestic foot. Domestic feet with a flat (zero) palmar surface have a crushed digital cushion, normally thin soles, thin walls and an assortment of heel related soreness. I am often asked, "What is the ideal palmar angle?" I really cannot say without a reference to breed, sport and conformation of each individual case. Digital Breakover To measure digital breakover, drop a vertical line from the apex of PIII to the ground surface. Measure forward to where the shoe or bare foot no longer touches the ground. This distance is the digital breakover. This point is where the hoof and shoe pivot forward as the heel leaves the ground. Prior to the heel leaving the ground, tremendous forces are executed around the apex of PIII. The coffin bone is actually suspended within a very flexible soft tissue, blood filled cushion. This very flexible, but yet durable, strong attachment is compressed in areas and stretched in others before the heel begins to lift. Therefore, I prefer to reference the point of digital breakover at a level compatible to internal pivot of the digit instead of a line carried along the face of PIII to the ground surface. This point of reference is dependent on sole depth and/or shoe thickness which play a role in the forces applied to the true point of digital pivot or breakover. The length of digital breakover becomes a valuable tool for the podiatrist team because manipulating this distance drastically changes the tension or resistance of the deep flexor tendon and other supporting ligaments and tendons. The pure lateral soft tissue detail film with wall and ground marker is a most valuable blueprint for the podiatrist team. Measuring the HL zone, sole depth, palmar angle and digital breakover, coupled with a working knowledge of soft tissue lesions associated with the four parameters, lays the ground work for the discovery and planning phases that should precede any and all therapeutic protocols. Without these parameters, I would have to resort to external manipulation as the only means to shift load or relieve other areas of compression and tension. Having good quality film available for the farrier prior to and following shoeing can be a tremendous asset for treating all career and life threatening foot problems. I sincerely feel it is the responsibility of all veterinarians to seek out the podiatry focused farriers and help them develop skills in reading basic soft tissue parameters and the silhouette images that directly relate to their respective job. Lucent Sub Wall & Sub Solar Lesions The lucent zone found along the junction of the opaque zone is a pathognomonic radiographic sign of laminitis. However, care must be given to the detailed characteristics of this lesion. The proximal and distal extents of the lesion have a small radius and the entire lucent zone has smooth, straight sides. When rotational changes have occurred the bottom zone is wider than the top and stops abruptly at the inner face of the sole. Even with cases of severe rotation and penetration of PIII, anatomically this is the distal limit of this lesion. The lucency found in the same general area that is pathognomonic for white line disease is strikingly different, as are the history and clinical findings. White line disease initially involves the white zone or non-pigmented zone of the horn wall. This term is very deceptive as the disease involves the non-pigmented horn between the terminal laminae, which is actually yellow to dark brown in color; not white. Regardless, the invading organisms apparently travel from the ground surface and invade a pre-existing weakened area of soft, white horn. We only have speculation at this time as to how the area is weakened, but evidence supports the hypothesis. Nevertheless the lucent zone is characteristics of horn invasion and differs greatly from that of laminitis. The entire margin of this air space is irregular with peaks and points that often appear to run inside the bone. They actually extend around the circumference of the hoof and are superimposed over the bone. The distal margin continues to the inner sole then emerges at the ground surface. Looking closely at the inner sole zone you will often find a molted appearance, which is normally dirt, small rocks, sand and other debris. This very significant finding may be missed or attributed to dirt on the outside of the foot. Lucent zones that represent gas forming, bacterial invasion of the soft tissue structures will have very distinct characteristics as well. They normally are small lesions, circular in formation, and can occur as a linear, small line or separate air dense areas along the sensitive junction. Extensive invasion can be seen to involve the bone as well. Old draining tracks can be seen within the horn wall, most having distinct marks visually seen on the surface of the hoof. Full thickness toe cracks often have a heavy scar that creates an invaginated area along the face of the hoof. A lateral radiograph will often reveal a lucent zone that appears to involve the wall. Lucent configurations can be found within the sensitive sole zone representing active gas forming bacterial sepsis, chronic abscess with or without serosanguineous pooling. With laminitis the very path of the apex can be tracked as it descends due to rotational changes and/or sinking. Lucent zones can be found in the heel and frog zones as well. Suppurative corns in the angle can be demonstrated by the pathognomonic lucent lesions more clearly seen on the skyline view radiographs. Severe bruising, with or without sepsis, can be seen as lucent zones along the sulcus of the frog and/or bar and lamellar zone of the bars. The skyline view confirms the lucent line seen on the lateral. Opaque Lesions Calcification of previously injured areas can be found within ligaments supporting the articular structure of the coffin joint and navicular bone. Areas of calcified hemorrhage can be found within the body of the deep flexor tendon as it courses down the pastern and over the navicular bone. Bone proliferation along the anterior face of PIII often involves the laminae as well as the bone. Laminitis cases that penetrate often have a tremendous soft tissue and bone proliferative response that can become permanently disfigured and often remain septic for the duration of the individuals' life. Calcified lateral cartilage is best demonstrated with soft-tissue detail and non-distorted radiographs. The foot placed in the tunnel and x-rayed with an oblique beam projection grossly magnifies and distorts the side bone formation. This often provides misleading data. The lateral and DP views taken with the beam centered at the coronary band provide the view of least distortion. Fracture lines are often associated with soft tissue pathology as well. The marginal fractures of the palmar surface of PIII often are found displaced and embedded within the sole corium and laminae. Wing fractures that are articular in nature often have a step formation at the articular surface. The step can also be seen on the DP view as the large section of bone is pulled distally via the deep flexor. My treatment addresses the tension on the deep flexor, which aids opposition of the fragments. This approach reduces pain and enhances healing. Fracture lines occur in at least eight planes. How do shoeing and trimming influence soft tissue zones and anatomical landmarks? Rasping the front wall in an effort to improve breakover is a common practice among farriers worldwide. The wall can only be backed up reducing breakover 3/8 to 1/2 inch. The significance of this technique is questionable. The opaque zone (sensitive/non-sensitive laminae) clearly reveals the mechanical loss of horn. Trimming has been mentioned as a means to reduce the radiographic distance between the palmar surface and the ground or shoe surface. Trimming also directly affects the palmar angle. Changing the palmar angle directly influences the alignment of the digits, in turn significantly altering the breakover of the shod or unshod foot. The farrier has a tremendous influence on the sheer mechanics of the foot. Knowing where the hotspots are and how simple manipulation can work to relieve these areas is the basis of all pathological shoeing. The foot, as a whole, is a unique and very complex organ. Altering one area directly affects others. The same can be said for pathology. Therefore, we must always be cognizant of the ill effects, as well as the positive effects, of our efforts.

2003 - 16th Annual Bluegrass Laminitis Symposium Notes Written and presented January 2003 by R.F. (Ric) Redden, DVM Horses with catastrophic injury or disease of the lower limb are most often euthanized as there is irreversible vascular, soft tissue and bone damage. Amputating the limb well above the dysfunctional area and fitting the horse with a prosthesis is a viable option. Successfully fitting a horse with a prosthesis is similar in some respects to that in the human field but stark differences make it quite a challenge. The ideal condition is the recently injured animal with hind limb involvement. Catastrophic injuries that involve the mid to lower half of the metatarsus or lower appear to respond more favorably than front limb problems, possibly due to weight distribution and the constant twisting load placed on the front end that is not imposed on the rear limbs. Selecting the right candidate: I was stimulated by the heroic efforts of Dr. Barrie Grant many years ago to attempt the seemingly impossible feat of providing a horse with an artificial limb. Dr. Grant’s work opened many doors of opportunity for me early in my career. I attempted many cases that had a primary injury and subsequent contra limb laminitis as my first candidates, a real learning curve. In most cases I had to flip a coin to decide which limb was more devitalized and which should be removed, and in spite of hopeless odds we almost succeeded on several cases. One mare that we successfully treated for nine months and was quite happy was euthanized due to severe colon torsion. A stallion, who bred mares with a homemade prosthesis for five seasons, was a total cripple but didn’t know it nor did he care, lost his battle due to colic. Many along the way were euthanized simply due to the failure to have an acceptable quality of life. These early cases made it possible for me to successfully save two quality bred mares heavy in foal with catastrophic, articular fractures involving the proximal metacarpus and lower carpal joints. Both were successfully amputated, fitted with a temporary prosthesis and delivered healthy foals. One mare was euthanized at the owner’s request, the other euthanized due to spiral fracture of the radius due to excessive pin wear. Hind limb amputation holds a bit more promise. Individuals presented with only unilateral involvement, without impending signs of contra limb laminitis, have all been successful attempts. Five cases remain productive and happy, with the longest case now approaching eleven years and the most recent case eight months. One stallion has successfully covered his mares for six years, one mare has for three years produced embryos which have been successfully harvested, and one filly I have lost track of after three years. The most recent, a Quarter Horse mare, has a healthy stump but apparently has phantom pain due to years of pain from osteomyelitis associated with complicated, chronic, unilateral laminitis. The procedure is quite simple, requires very few surgical tools and can be performed in most any location. Using a sling for induction and recovery certainly reduces the risk of injury during recovery. The sling must be used for the second cast and several prosthesis changes until the horse has learned to stand unaided by the sling. Therefore a sling set up is imperative; I prefer a twelve foot ceiling and a Liftex sling. Procedure: The level of amputation is a great consideration. When the foot and coffin joint are involved, I try to leave PI and the germinal centers of the coronary groove, digital cushion and frog. Provided these structures remain vitalized they can be brought up over the end of PI, and sutured to the existing tendon and skin. Most auto graphs have been successful providing the stump with a tough pad that seems to serve the horse well. Amputations higher up, mid cannon, I do not attempt to get primary healing of the stump but prefer a healthy, granulating bed over the bone that soon becomes a nice receptive area for a germinal frog graft. At two to three weeks post amputation the stump is healthy and ideal for a graft. A foot on the opposite end of the animal is fitted with a hospital plate shoe, the frog trimmed very thin and surgically prepped. Once under general anesthesia, the cast and temporary prosthesis is removed, the hospital plate removed from the shod foot, and a small strip of germinal tissue is removed along the body of the frog. This strip is then cut into small pieces (1-2 cm. in size) and implanted throughout the granulating stump. Pad the stump with ½ inch felt, cut to fit snugly and apply a cast using the pins to support the limb and protect the stump. All cases treated in this fashion have grown a zone of cornified horn, some have wall tubules with frog tissue others just frog tissue. The results have been very stimulating and demand further research. The actual amputation technique is quite simple and straight forward; just remove the diseased tissue, dissect away the frog and digital cushion, leaving it attached to the vascular supply. Then fold the germinal tissue forward over the end of PI. A transcortical cast provides pain free post op care for three to seven weeks. Once micro fractures form around the pins they must be removed and the stump loaded. The temporary prosthesis can be made in a typical shop using a variety of materials. I prefer ¼ inch aluminum plate to form the stump for the lower amputation. The higher amputations must have adequate leg extension that can be made with aluminum pipe, PVC for lighter horses or even wood. The goal is to simply replace leg length and secure it to the limb so it doesn’t twist or fall off. I hope to soon provide a monograph that shows many various ways to build and fit a temporary or even permanent prosthesis. If you have a candidate please call me and I will do all I can to help you assess the case and walk you through each step of the procedure.

Indepth Equine Podiatry Symposium Notes Written and presented January 2010 by R.F. (Ric) Redden, DVM PIII fractures have been described in the literature and classified according to location, which can be helpful for those familiar with the classification. However, even though PIII fractures as a rule do not occur as commonly as other acute foot problems, they should be considered in your tentative diagnosis when acute lameness is presented. Foot abscesses are far more common than fractures and should also be considered high on the suspect list. The clinical signs and history of spontaneous foot pain is classic for both syndromes. Distinguishing PIII fractures from the abscessed foot is often not as straightforward as one would think, as quite frequently radiographs do not clearly reveal fracture lines for a few days, even weeks, following injury. Also, fractures occur in several different planes and other locations that are not described in the literature, which further complicates the diagnosis. Fractures can occur along with septic conditions that appear to be the primary problem and often overshadow the initial problem. Pathological fractures can occur due to cumulative damage from other disease syndromes such as laminitis, full thickness toe cracks, abscess, white line disease, high grade club feet, etc. Palmar Rim Fractures This type of fracture can occur due to direct trauma sustained when horses gallop over hard ground (dry or frozen), with extremely thin soles. This condition clearly mimics bilateral laminitis as the clinical signs are quite similar. Radiographs can be conclusive; however a very soft exposure is required to visualize small fragments of bone that have broken away from the very thin palmar rim. The 65 ° DP view and 45 ° 65 ° medial and lateral oblique views reveal the fracture best. It can also be seen on the lateral and occasionally the DP view. Shoes should be pulled for these views to prevent superimposition of the shoe over the area of concern and unwarranted scatter radiation that reduces resolution and detail. Very low KV, high MA and very low MAS are used to clearly reveal the fracture. This is not a problem with traditional film as you simply cut the KV 5-10 units and significantly reduce time, which drops MAS. MA is always at its highest peak at low KV settings. If you must use a hot light to reveal the fracture, you most likely will miss a few. When using a digital unit you may not have the option or means to create a very soft exposure simply due to pre-set algorithms. I prefer my traditional system for all foot images over most CR and DR units as it offers far more flexibility and higher detail and resolution. Treatment Unless the fracture becomes septic it does not need to be removed. A protective hospital plate shoe and limited exercise for a few weeks works well for my cases. When septic, this fracture can be confused with acute laminitis as there may be drainage from the sole and the clinical signs are very similar. However, the horn-lamellar (HL) zone does not confirm laminitis and even though the sole may be quite thin, it is not due to PIII displacement. Septic bone fragments should be removed and the sole protected by a hospital plate shoe until it has healed and cornified. I apply the shoe, apply a surgical scrub to the sole and remove the fragments using a local block and light sedation. A hospital plate works great when applied prior to surgery as it makes a nice pressure pack, preventing unwarranted granulation tissue. When used properly, this shoe does not increase the risk of post op sepsis. Type 1 Wing Fractures Wing fractures normally occur on the right front medial wing in horses working at high speed going counterclockwise medial wing left front when working clockwise. The coffin bone at the time of birth is quite small relative to the hoof and has a totally different shape as the wings of the bone have not developed. The wings grow from the body of the bone, with the majority of growth occurring over the first year of life. However, with most breeds the wings may continue to calcify and grow in length for 10 years or more and in rare cases can extend to the limits of the heel bulbs. Saddlebreds and most Arabian horses have a very short palmar surface relative to their size in comparison to other horses. Bone shape is as unique to the breed as hoof shape is, which is why there are many capsule stereotypes that we can recognize from breed to breed. Acute wing fractures appear radiographically as a distinct fracture line that is normally quite small and can be difficult to diagnose at the time of injury. Very soft 65 ° DP and 45 ° 65 ° lateral and medial oblique views as a rule reveal the fracture best. However, the skyline view shot through the heel as well as DP oblique view can also reveal the fracture. Areas of isolated ossification on PIII that occur quite frequently due to the normal wing maturation process can often be confused with a fracture when there is a history of heel pain. Note that the areas of separate ossification as a rule are not painful, and have distinguishing characteristics from fractures. Treatment Wing fractures as a rule are quite easy to treat, as stall rest for a few weeks and a bar shoe with good frog support allow most horses to continue training after 3-4 months of very limited exercise. Many of these fractures do not heal bone to bone, but form a gelatinous union that may appear to have callous formation. Palmar digital neurectomy has been used quite successfully as an alternative to taking the horse out of training for 3-4 months. The dark side of this treatment option is the occasional neuroma and inherent risk of hot nails, puncture wounds or excessive trauma to the desensitized heel. Articular Wing Fractures Articular wing fractures pose a slightly different problem than Type 1 wing fractures as they are normally very painful, causing grade 4-5 lameness, and most can be demonstrated radiographically at the time of injury. Only a few cases will require a few days to displace before being revealed radiographically. Several views are needed to fully assess the fracture. 65 ° DP view with moderate penetration. This view reveals the joint margin. The thinner areas of the coffin bone will be overexposed when using traditional film.65 ° 45 ° oblique view. Adaptable oblique angles can often clearly define the path of the fracture.DP view with hard penetration and beam centered just below the coronary band. This is one of my favorite views as it reveals the distal displacement of the main body of PIII. The 65 ° DP view may also reveal a step fracture, but fails to clarify the plane of displacement. Looking closely at the DP view from a mechanical point of view and considering the broad attachment of the DDF and its function, one can better understand how displacement occurs. As load goes on the foot, the action of the DDF pulls the larger body of bone distally as it is no longer anchored to the wing. The displacement and constant movement of the two separate pieces of bone is most likely the seat of pain. Treatment Articular wing fractures as a rule do not pose a serious problem even though they are often very painful for several days. Some heal bone to bone with four months rest and a simple bar shoe. Others never heal but have a distinct fissure line for the remainder of the horses life. Those that heal with a step at the joint invariably have some ° of arthritis that can cause future soundness issues. For some unknown reason, grade 2 or higher club feet are more prone to articular fractures than the lower PA profile feet. Traditionally bar shoes, cap shoes and foot cast have been used to treat the acute pain as well as the fracture. Dealing with the pain is our first priority, as it potentially causes very serious and often life threatening contralimb laminitis. Considering the cause for pain can lead us to a meaningful solution. Greatly decreasing DDF action minimizes or prevents fracture displacement, and consequently diminishes the pain associated with the grating together of raw ends of bone. However, it is prudent to prevent DDF tension from displacing the large body of PIII shortly after injury as the natural healing mode quickly fills the fracture gap and can jeopardize successfully re-establishing good joint alignment. A large majority of articular fractures never heal bone to bone, but form a callous that bridges the surface of the bone. A cartilaginous matrix forms along the center of the fissure line. Radiographically this may appear to have a bony union but it is often the superimposed bone on the surface that offers this illusion. I have taken several coffin bone fractures from retired horses that apparently had articular fractures as two and three year olds. They have either died of old age or were euthanized due to the infirmities of old age, and close scrutiny of the boiled out bones have provided conclusive evidence of this type of bony bridging. How to Adequately Reduce Displacement Before determining a shoeing protocol, know the existing PA. Use a shoe or device that will raise the PA to a minimum of 20 °s. A self-adjusting rocker action device with wedge is preferable over a straight wedge setup as the horse can pick and choose the precise PA that not only provides stability but also more pain relief. The large majority of cases show a favorable response to pain within minutes after application despite increased heel loading from the high PA. The fragments apparently do not grate against each other. More conservative shoes can produce good results, however the pain response is extended over that of quickly reducing inward folding of the large body of bone, and most therapeutic shoes do not address DDF tension. Therefore the majority of fractures heal with a step malalignment. Most articular fractures require 4-5 months for recovery. When the step persists, arthritic conditions are a threat to soundness. Nerving is an option for articular fractures and is often used as a last resort when the goal is to return to athletic training. However, complications can arise from neurectomies. Hot nails from routine shoeing are a higher risk than normal, and puncture wounds from wires, nails, loose shoes, and sharp objects often go undetected for several days as lameness is obscured by the neurectomy. Sequestrum can form along the fracture line when a horse continues training and cannot feel the pain. The sequestrum often becomes septic and can potentially be life threatening. Extensor Process Fractures Fractures through the extensor process are relatively rare, but are quite painful and may be difficult to assess clinically. Cases with acute fractures and cysts within the extensor body are normally sounder when moving over hard ground rather than soft, which is just the opposite of most load induced foot problems. As the heel drops into soft footing the hyperextension of the coffin joint impinges the fracture, causing the painful response. Non-union fractures have been found in weanlings and yearlings that have never had a history of lameness. These fractures resemble separate centers of ossification more than they do a fracture. I have examined high level performance horses and found this type of lesion as a coincidental finding. Others have developed low grade lameness that appeared to be associated with the lesion. Treatment The majority heal within a few months provided they do not become displaced. Using a low to mid scale mechanical shoe prevents the extensor process from having contact with PII when extended load is applied, and helps reduce flexor displacement if a consistent PA is maintained. Casting the lower limb and foot in conjunction with this shoe is also an adjunct to preventing displacement. Foal Fractures As the foal's foot develops, a weakness occurs along the parietal groove that predisposes this area of the wing to fracture. As a rule this fracture occurs before 4 months of age and can be quite small or up to several millimeters in width. While normally found on the medial wing, it can also be on the lateral wing and can include one foot or all four simultaneously. The shape of the fracture is relevant to the ° of lameness. Deeper fragments or those with a triangular shape can cause grade 3-4 lameness that may persist for 4-5 days then dissipate with nothing more than stall rest. Examining large numbers of weanlings on three separate Kentucky horse farms I found that 99% of the foals on one farm had fractures.1 This farm had a dense grade and run in shed, and the foals had minimum foot mass due to excessive wear. One farm had 84% of foals with fractures, with only two out of better than 50 foals showing any signs of lameness. The third farm had 26% fracture occurrence. Its 40 plus foals were never trimmed and all had good foot mass. Treatment Some have advocated putting shoes on feet with fractures. In my experience I have not found that they heal any quicker with shoes than they do without, and those without shoes have a much better foot shape and size than those shod at an early age. I keep my foals in the stall until they are sound, then put them out with the rest. Close observations confirmed that most fractures with noticeable lameness occurred during the wettest weather and most all foals examined had less than optimum foot mass. Implementing a 4 point trim program to generate foot mass and using Keratex Hoof Hardner to stiffen the hoof during wet weather reduced the farm with an 84% incidence of foals with fractures to 4% incidence. This appears to be a very effective way to prevent developmental fractures. I am not sure how significant the findings are as all fractures appear to heal quite well over 6-8 months, however they become a space occupying lesion that impinges on the vascular supply in the area of the fracture. When examining 65 ° DP radiographs on two year olds that have had a fracture, the fracture site may appear as pedeostelitis, but instead of being along the entire medial wing it will have a very distinct start and stop margin. Possibly quarter bruising and quarter cracks can be associated with these areas of mild vascular impingement. Fracture of the Face of PIII These fractures are rare but must be considered life threatening. How and why they occur is unknown; all cases I have examined were in performance horses. The fragments appeared along the face of PIII, revealed with a lateral view. A lucent line appears just below the surface of the face of PIII in most all healthy feet. Apparently, this area is weakened to some ° and the tension applied by the laminae and Sharpey's fiber connection to the bone pulls the piece of bone from the face. By and large these fractures go undetected in the early stage. Most all will become a sequestrum and become quite septic, causing grade 3-4 lameness. Cases that are bilateral are frequently misdiagnosed as laminitis and can be life threatening once septic. Treatment Treatment consists of removing the necrotic bone ASAP. The wall is removed over the fragment and all necrotic bone and soft tissue is removed. To avoid exuberant granulation tissue it is best to pack the surgical area firmly with Betadine soaked gauze. Changing the pack daily for the first several days is indicated. Chronic septic fractures may require bone curettage as often the surrounding tissue is involved or becomes necrotic. I prefer to use Lacerum®, a platelet derived growth factor product, with these cases. Treated in a timely fashion this fracture does not pose a serious threat to horses and they can resume training once fully healed. Failure to remove dead bone can be life threatening. A DDF tension reducing shoe that creates a 10-15 ° PA helps stabilize PIII in a more consistent plane Prognosis is quite good when early detection and efficient debridement have been accomplished. However, delaying removal of the necrotic bone can become life threatening and can cause severe, septic focal induced laminitis. Sagittal Fractures Sagittal fractures are comparatively rare relative to the occurrence of wing fractures. They can occur for several reasons. One in particular that I have observed is young stock striking a solid wall with a front foot or kicking a concrete or brick wall with a hind foot. This fracture can cause very intense pain and most exhibit immediate non-weight bearing lameness. Once again I feel the action of the DDF is the seat of pain as it causes grating of the two fragments when load is applied to the DDF. These cases only touch the toe to the ground and cannot put the heel down, which engages the DDF, causing the fracture to displace along the distal margin and jam at the dorsal margin. Treatment Applying an 18-20 ° self-adjusting PA shoe or device has offered many of my patients immediate pain relief, allowing the fracture to heal with a bony union and little or no displacement over a period of 4-5 months. Reducing and stabilizing the fracture with a cortical screw has been successful in the hands of select surgeons, but as a rule sepsis has been a big drawback for the procedure. Pathological Fractures Chronic high scale laminitis leaves the coffin bone very weak and vulnerable to all sorts of fractures that can occur along the medial/lateral wing, palmar rim and large fragments along the face of PIII. When a significant piece of bone is lysed or fractures from the main body of the bone, there is inherent risk of a subsequent fracture of the coffin joint. This invariably causes full blown joint sepsis, which is often fatal. Treatment A chronic, high scale laminitis foot with joint sepsis has a very grave prognosis for a quality life. While they can survive for months or even years, the quality of life is often questionable at best. References Kaneps AJ, O'Brien TR, Redden, RF et al. Characterization of osseous bodies of the distal phalanx of foals. Equine Vet      J. 1993 Jul;25(4)285-92.

Written and presented July 2006 by R.F. (Ric) Redden, DVM Introduction Limb deformities are commonly found in new foals. They can be congenital or developmental and with varying degrees of deformity ranging from mild to severe. The majority of deformations will fall into one of five basic categories. 1. Angular - Angular deformities occur when the distal extremities of the limb deviate from the midline of the limb. Valgus deformity is a deviation lateral of the mid line. Varus deformity is a deviation medial of the mid line. 2. Axial - Axial deformities can be described as a medial or lateral shift at the anterior articulation, e.g. offset knees. 3. Rotational - Rotational deformities are muscular in origin and most commonly involve the front limbs. The limb itself may have acceptable alignment, but rotates outward due to muscle attachment variation. At first glance, these foals appear to have a valgus fetlock. 4. Spiral - Spiral deformity involves the metacarpal in the majority of cases but can also involve the metatarsus. At first glance the spiral deformity resembles toed-in conformation. The author refers to this deformity as heeled-out, as the pure spiral does not have a varus fetlock. 5. Flexor Anomalies - Flexor contraction and weak flexors are often found at birth. How to Assess Foot Flight and Leg Alignment Start by watching the foal walk straight away from you, preferably on a smooth surface. Walking the mare along a wall or fence offers a reasonable means of assessing the foal as he travels beside the mare. Focus on foot flight and the landing phase. Watch the hind feet land several times before focusing on the front feet as the foal moves away from you. Foot placement and full load stance appears to occur faster than the eye can detect, but with practice the landing phase can be observed in a slow motion mode. Closely observing the air space under the foot as it lands and loads acts to slow the action and brings out subtle details that might otherwise be overlooked. Next, observe the foot flight and landing pattern of the front feet as the foal comes back toward you. Watch the lateral wall of each front foot land, then observe the medial wall. Note any differences between the two feet. Turn the foal and watch him go away from you once again. This time observe the hind limbs, one at a time, from the hip to the ground as the limb flexes and extends to full length. Placing an imaginary dot at each major joint creates a reliable means of evaluating the angulation. Once both hind limbs are observed focus on the front limbs, paying particular attention to the carpass and the heel of each front foot. The heeled-out foal (spiral deformity) and bowed knee (varus carpass) becomes readily detectable by the trained eye as the foal moves away from you. As the foal walks back to you observe only the front limbs, one at a time, from the shoulder to the foot. Once again, place imaginary dots at each joint. Connect the imaginary lines between the dots as the limb flexes and extends, and as the foot lands. Foals that aren't broken to lead well are more difficult to observe, but with practice the eye can be trained to follow the dot system even at a trot. Once the foal has been evaluated while moving, observe him standing as squarely as possible and in a relaxed position. Assign imaginary dots in the following 7 places: 1st dot: Most proximal point on the forearm. A small swirl of hair is normally located at the top and center line of the radius. 2nd dot: Center of the distal radius at the level of the physeal plate. 3rd dot: Center of the most distal aspect of the carpass. 4th dot: Center of the proximal cannon. Note this dot will be superimposed over dot 3 unless axial deformity (offset knees) is present. 5th dot: Center of fetlock. 6th dot: Center of coronary band. 7th dot: Center of toe. As the dots are observed, visualize an imaginary line between them and note any deviations of those lines. Next, imagine an imaginary laser or arrow centered on each dot, passing through it on the sagittal plane of the limb at that point. Observing these imaginary lines is a reliable, consistent method for identifying planes of deviation that can and often do occur between major joints. Using the dot system helps train the eye to look for minute details that may otherwise be missed in addition to greatly enhancing communication between those observing the foal. Each type of deformity can be graded on a scale of 5: 1. Noticeable to the trained eye. 2. Noticeable to the experienced horseman. 3. Noticeable to the inexperienced horseman. 4. Noticeable to anyone. 5. Off the scale - catastrophic class deformity. Any given individual may have several types of deformities in any one limb. Developing this system and using it in a disciplined, methodical fashion offers a reliable means of assessing foot flight and leg alignment. Identifying the real problem is a vital step for an efficient treatment protocol. Valgus Deformities Treatment Options 1. Stall Rest - Newborns with less than 15 degrees of deviation often respond in a favorable fashion with a few days of stall rest. Various degrees of valgus conformation appear to be a natural finding with most all species that have a long front limb relative to neck length. 2. Medial Extensions - Those that fail to respond sufficiently with confinement can be improved by applying a medial extension to the foot of the affected limb. Several products can be found on today's market that offer quick, easy temporary medial extensions. 3. Self Correction - Valgus deformity appears to be self-correcting, as the large majority of valgus foals will steadily improve until they reach full growth. Unfortunately, today's market for young performance stock and a lack of patience has changed the scope of raising young horses, routinely speeding up the corrective mechanics as a result. Low grade valgus deformities can be seen in mature, very successful race horses and may simply be a variation of normal. 4. Surgical Correction - Periosteal elevation and physeal bridging are also means of surgically aiding correction with non-responsive or greater than 15 degree deviations. 5. Therapeutic Trimming - Therapeutic trimming requires caution. Lowering the lateral side of the hoof in young foals in an effort to bring the toe to center can be detrimental, as it can cause permanent deformation of the fetlock joint and hoof capsule. Varus Deformity Varus deformation most often occurs at the fetlock. When it occurs at the carpass it is referred to as bowed knees. Thirty years ago valgus deformities far outnumbered varus deformities, but the opposite is true today. A correlation may exist between incidence and growth rate. Early muscle development and heavy body mass may play a role in the increased incidences found in most breeds today. Treatment Options for Varus Fetlock Surgery - Periosteal elevation over the medial and distal MCIII physis can be an effective treatment when performed within the first three weeks of age. Caution: Surgery at one week of age can result in overcorrection. Overcorrection creates a valgus fetlock, which is an extremely rare deformity. The lateral anterior surface of this fetlock joint is proximal to the medial side. Thoroughbred foals that are born with linear long bone alignment are often referred to as straight-legged foals and may be perceived as normal. Unfortunately, in absence of the natural valgus stance, many will develop varus fetlocks within weeks. To prevent this unsightly and costly deformity, periosteal elevation is performed at 1 week of age. The results can offer cosmetic approval on sale yearlings as they appear acceptable when standing, but have a very strange foot flight pattern as the fetlock flexes in an abnormal plane. Further studies need to be conducted to fully evaluate how the valgus fetlock affects racing soundness. Therapeutic Shoeing - Applying a lateral extension with slight lift can be very effective. The developmental stage of the distal MCIII physis closes very early. Although physiologically closed in 90 days, the most effective window of response is during the first 30 days. Trying to correct varus fetlocks once the foal has reached 3-4 months of age is futile. Unlike a valgus carpass, which remains responsive for many months, the fetlocks mature very quickly. Therefore when observing a foal with a valgus carpass and varus fetlock, the initial focus should be on the fetlock. Once past the stage of responsiveness, focus on the carpass. Note that overzealous trimming (lowering the medial wall) does not appear to have the detrimental side effects found with overcorrective trimming in valgus foals. Therapeutic Trimming - Lowering the medial side of the foot can offer desirable results with low grade varus deformities. Deciding whether to lower the toe, heel or both is the decision of the farrier based on his experience with corrective trimming. Correction should be put on the untrimmed foot. Trimming the foot on a young foal, then applying correction can be detrimental to the development of the foot and often causes post trim lameness. Note that the varus foal will often have a medial sheared heel with a similar appearance to the valgus foal. More studies are needed to better understand the etiology of the sheared heel. Axial Deformity When the cannon bone (MCIII) is displaced lateral to the carpass the deformity is referred to as offset knees. This deformity is not desirable for speed horses and should be distinguished from the canted knee that is often described as offset. The canted knee sits squarely on the proximal cannon. Using the imaginary dot system, the dot at the center of the base of the carpass will be superimposed over the dot at the top of the cannon. The dot at the top of the carpass (center physis), however, will not be in a linear line with the lower dots (see diagram). This line down the radius will be perpendicular to the ground surface but medial to the peripheral lines along the cannon bone. Axial deformity is often referred to as offset, and therefore not considered undesirable. Use of the dot system will clearly distinguish it from the offset knee. Many top race horses have canted knees that apparently cause no threat to soundness. Therefore the deformity may simply be a variation of normal. The dot at the top of the cannon will be lateral to the dot at the bottom of the carpass. When both offset and canted, the cumulative effect of the deformity is very noticeable and undesirable as it leads to unsoundness. Treatment Options No treatment exists at this time. Spiral Deformity Spiral deformities appear to toe in. In pure spirals the fetlock has normal alignment, therefore it is not a varus or toed-in deformity, and is best referred to as heeled-out. This deformity creates a twist or inward spiral involving the metacarpass (MCIII), which may be located from just below the carpass to the fetlock. Looking closely at the foot, you will find it is quite symmetrical relative to the degree of deformity, which indicates that the foot is loaded in a natural fashion. Varus and valgus defects will shift hoof mass medially or laterally depending on the area of excessive load, and will most often have a medial sheared heel. Defining the Deformity Holding the cannon bone in your hand and flexing the foot via a finger centered on the pastern can help distinguish a spiral from a varus fetlock. A center point between the bulbs of the heel will remain flexed in line with the pastern as the fetlock is flexed. The foot and pastern flex medial to the cannon bone when the fetlock is varus. Watching the spiral horse walking away clearly reveals the lateral heel. Normally the heel of the front foot cannot be easily observed as the foal walks straight away from you. Identifying the spiral at an early age is difficult, as the fetlock is a very smooth, round joint with no center point of reference. The finger test is a reliable means of distinguishing the young foal spiral from the varus fetlock. Observing the arrows through the dots helps distinguish the spiral from the varus fetlock. An arrow through the center of the top of the cannon will be in a plane lateral to the plane of arrows through the center of the fetlock. The pure varus fetlock will produce arrows in the same plane. Treatment Options There is no known effective means of correcting the spiral in the long bone. A surgical osteotomy would be an effective treatment if the outcome outweighed the disadvantages. Failure to identify the spiral and trimming the foot as though it were a varus deformity will quickly create an imbalanced foot that becomes a permanent disfigurement and leads to unwarranted foot problems. Cosmetic shoeing can camouflage this deformity and is a common practice with sale yearlings. However, artificially moving the center of the toe more lateral improves the front conformation view, but does not alter the heeled out aspect of the deformity. Rotational Deformity Rotational deformities are often called toe-out as the toe deviates lateral to the mid line. With pure rotational deformities the limb alignment will fall within acceptable conformation standards but the entire limb, including the scapula, is attached to the thoracic cavity in a plane that deviates lateral to the sagittal plane of the animal. Due to the plane at which the limb is attached to the body, the lateral side of the foot is closer to the ground as the limb approaches the landing phase. The more severe the deformity, the longer the time frame from touch down of the lateral side of the foot to full stance phase as the medial side lands and loads. It is the medial side of the foot that incurs a large majority of load once the foot is fully loaded instead of the lateral that lands first, thus setting the stage for excessive internal trauma that often results in sheared medial heels, crushed digital cushion and quarter cracks involving the medial heel. Quarter cracks are rarely found involving the lateral quarter of breeds with a tendency to have some degree of rotational deformity. When present they are the result of direct trauma to the lateral side of the foot or coronary band and usually connected to an injury when found. Standing off to one side of the foal's center line, look at the face of the knee, fetlock and toe and use the imaginary arrows passed through each dot. Pure rotational deformity exists when the arrows are on the same plane but lateral to the sagittal plane of the foal's spine. This system helps rule out the often misdiagnosed valgus fetlock, a very rare deformity that only occurs as the result of injury or periosteal elevation of the medial distal physis of MCIII at a very young age. To convince others who have trouble seeing the deformity, sedate the foal, stand him up as squarely as possible and slowly pull the elbow away from the chest. Pulling the elbow away from the chest will align the limb along the saggital plane of the animal. This is an easy way to evaluate the degree of self-correction that can occur with the same amount of chest development. Treatment Options Correction is self-adjusting in most breeds other than the quarter horse. As the chest develops the increased thoracic mass pushes the elbows outward, rotating the limb toward the mid line. Colts develop their chest muscles at an earlier date than fillies, and often correct this deformity by 12-18 months of age. Discretion should occur with corrective trimming. Lowering the lateral wall to achieve flat or uniform landing should not be attempted with this deformity, as it grossly distorts the hoof capsule, adversely alters the physeal plates of the fetlock joint and has no influence on the developing chest and limb attachment. Flexor Contraction New born foals with deep digital flexor contraction involving only the last digit are the most common and fortunately the easiest to treat. These foals will be on their toes at birth. The palmar surface of the foot may form a 30 degree to 45 degree angle with the ground surface. Treatment Options 1. Tetraglycine given at a dose of 2-3 grams IV, preferably diluted in saline can be very effective with results evident within hours of administration. Two to 3 grams of tetraglycine can be repeated every other day if indicated. Very young foals seem to be more responsive to this treatment than older, more mature ones. Caution is due with tetraglycine. Adverse effects can cause sudden death while administering tetraglycine to foals. Despite very low risk, the client should be informed and consent to treat the foal prior to administering the drug. Time is of the essence to obtain best results. The stronger the foal becomes, the more difficult flexor contraction is to correct. 2. Bandaging the lower limb with a firm combine cotton bandage from the carpus to the ground can produce favorable results for foals with mild flexor contractions. 3. Passive extension stretching in conjunction with bandages is also very helpful with milder cases. 4. Air splints have been advocated as a means to relax the flexor group. 5. PVC Splints can offer favorable results with most flexor contractions. The author prefers to use custom molded, thin wall PVC down the posterior side of the limb as a means to quickly weaken the flexor group. The foal is sedated and bandaged from the elbow to the ground surface with firm-fitted combine cotton. Use an amount adequate to protect the sensitive skin. Cut a 36 inch piece of thin wall PVC pipe down each side. Fit one half of the pipe down the back of the limb, 2-3 inches below the elbow and an inch above the ground surface. Using a heat gun, warm the top until the PVC becomes soft. Wear gloves, as it will be very hot. Quickly trim the corners with a pair of scissors and fit the top of the half pipe to the back of the forearm. Hold in place until it has cooled. Heat the area of the pipe that will fit over the back of the carpass in the same fashion, allowing it to cool in place. This step is very important. The custom fit over the forearm and carpass prevents unwarranted pressure sores and tell-tale white hairs. Heat a small area at the fetlock and cut a small pie-shaped wedge out of each side. This allows the lower pieces to flex, fitting closer to the shape of the pastern. Vet wrap the pipe to the bandaged limb, then secure it with a roll of 4 inch Elasticon. Foals only a few hours old will normally respond quite favorably within 4-6 hours. One or two week old foals will require 12-24 hours in the splinting. Two to three days may be required for foals 2-3 weeks of age. Often, foals born contracted develop a mid to high grade club foot later in life. This bandaging technique can offer favorable results to club-footed foals of 3-4 months of age, as well as grade 3 club feet in weanlings. When treating club feet and older foals that may require a few days in the splint, it is best to apply a glue-on Dalric® raised heel shoe or a full rocker aluminum attached with Equilox® before splinting. The shoe will protect the toe - as foals will drag the toe while the splint is on - and releases tension on the DDF. Note: the author finds best results are achieved by leaving the splint on the leg long enough to create hyperextension of the carpass. Caution is due. Hand walk or restrict the foal to stall rest until the carpass is once again in its normal position. Do not turn foals out with hyper extension of the carpass. Often foals respond quite well with one treatment, but occasionally the robust, fast growing individuals will go upright and show mild signs of contraction as a result of sporadic growth spurts. Repeat the process as often as needed to control the affects of contraction. 6. Toe extensor shoes have been advocated and used to stretch the DDF network. Caution is needed, as the hoof capsule, coffin bone and laminae are very immature and are easily damaged by excessive pressure. It is quite easy to permanently damage the apex of PIII, create a dished hoof, or in extreme cases, slough the entire capsule due to excessive tearing of the laminae. Conclusion Accurately assessing angular deformities requires keen observation. Using the imaginary dot system offers a reliable means of training the eye for the minute, characteristic differences that make each limb on each individual a unique study. This methodical approach also offers a means to become more familiar with the range of norm that is influenced by breed, age, use and environment. Many foals have multi-facet deformities, some being compatible with future soundness, others not. Undesirable characteristics need to be distinguished from potential soundness risk deformities, and when attempting to correct foals we must keep first and foremost in mind what is best for the future of the animal.

2009 In-Depth Equine Podiatry Symposium Notes Written and presented January 2009 by R.F. (Ric) Redden, DVM Puncture wounds are a direct or indirect introduction of bacteria into the sensitive zones of the foot. They can be career or even life threatening and range from subtle and difficult to locate to quite severe and devastating to soft tissue and bones. Regardless of their form, they should never be taken lightly. Treat all puncture wounds with the respect they deserve, as what initially seems like a routine problem can quickly get out of control and threaten the career or even life of the horse. Indirect Puncture The most commonly occurring puncture wound is an indirect introduction of bacteria into the foot via small fissures that open along the terminal laminae. Once the laminae reach the inner sole surface they cornify and become non-sensitive. The cornified cells resemble the anatomy of the sensitive laminae but have a totally different function. The zone of laminae that lies between the wall and sole is called the terminal laminae, and it acts as a buffer union between the wall and sole, as they grow at the same rate. The terminal laminae were formerly referred to as the white line, a term that has been the subject of much debate simply due to its non-descriptive meaning. The only white zone of the hoof is the stratum medium, the inner, non-pigmented horn wall that lies between the outer horn and the laminae. This white zone runs the length of the horn wall, is clearly seen at the ground surface and is often referred to as the white line. The fissures that allow bacteria to enter the sensitive laminae and sole corium occur in the terminal laminae and innermost area of the non-pigmented horn layer. They are the product of poor quality protection, which occurs as a result of insufficient hoof mass . The wall fails to be protective due to less than optimum density, toughness and mass. Ground friction carries bacteria motes into the sensitive, blood rich laminae and sole corium, breaching the last zone of defense. Clinical signs: Clinical signs of an abscess include acute, Obel grade 5/5 lameness, a hot foot and a thumping pulse. Diagnosis: Suspect areas will have little black lines in the terminal laminae and inner horn wall. Very light hoof tester pressure can quickly locate the area of concern. Be cautious. Use the tester lightly over areas of the foot where you do not suspect sensitivity and work towards the likely sensitive area from both sides. Avoid putting pressure directly over the hot area. The horse has enough pain without us causing any more. Note that an abscess can be quite easy to confuse with laminitis, especially when it is found bilaterally. Radiographs can help make this distinction. Treatment: If the horse is wearing a shoe, pull it one nail at a time using a crease puller or side cutter to easily crack each nail out. Yanking the shoe off with a shoe puller, a very common way to remove shoes, will cause the horse extreme pain and can result in injury to those who are holding the horse. Lightly rasp the foot, looking for any small, dark fissures that run perpendicular to the terminal laminae. Quite often there will be several such lines, especially in the bare foot. Identify the ones closest to the seat of sensitivity with the tester. Using a small curette or the end of a farrier knife, make a small hole along the wall side of the fissure. Stay away from the sole side; this will prevent the unwarranted problem of solar prolapse that frequently occurs when the sole is opened. After opening a small area, insert a horseshoe nail with a small bend at the tip into the fissure, which you can now see penetrate well above the sole margin. Tip it in towards the sensitive sole until you get a drop or two of exudate. At this point you have vented the abscess. I often make a notch in the outer wall at this location, put a piece of Betadine/DMSO soaked cotton in the hole and reapply the shoe, leaving out any nails that might be too close to the hot, sensitive area, clinching down very easily. When the foot is extremely painful, block the foot before nailing and be careful not to stick the foot while it is desensitized. The shoe protects the opening to the fissure. I frequently administer antibiotics for 5-7 days and Bute for a couple of days. Within 3-5 days the horse should be 100% sound without the benefit of Bute. Bone Involvement: Bone involvement is rare in an indirect invasion of bacteria, but it is possible. If the horse remains sore (not lame - just sore) after 5 days, bone involvement is likely and radiographs are highly indicated. Radiographs: Take a 65º DP in a Hickman or Redden style positioning block. This will greatly limit distortion and enhance your ability to see very subtle lucent zones along the palmar rim. The commonly used tunnel distorts the 65° DP image, reducing our ability to detect subtle changes. I also take a 65º 45º oblique view and occasionally a DP view with beam alignment at the level of the palmar rim. All exposures should be extremely soft, or you will miss the subtle changes that occur long before there is significant bone loss. When using digital units it is imperative to develop a technique chart includes a range of contrast below a standard "one shot" technique. While the contrast on the digital image can be manipulated with software, there is a limit to its range. I frequently review digital film that does not reveal palmar rim alterations as the range of contrast has been exceeded. Complications from a hot nail: If the foot becomes hot 3-5 days post-shoeing, pull the shoe, locate the sensitive areas with a hoof tester, then open the sole wall junction just enough to let a few drops of exudate to escape. With other direct nail or foreign body punctures, note the color of the exudate. If the exudate is yellow and thick or green and has air bubbles, suspect a pseudonoma or proteus invasion. As a rule there is bone involvement in these cases as both types of exudate are caused by very virulent organisms. Culture sensitivity is indicated, along with baseline radiographs. Chronic indirect punctures: When an abscess has persisted for several days to weeks and the horse has alternated between lameness and soundness, the problem must be sorted out quickly for several reasons. Bone sequestrum can form, large areas of bone can be eroded and contra limb laminitis becomes a concern for the opposite foot. At this stage the abscess is career threatening and can easily become life threatening. Immediately apply a Modified Ultimate with Advance Cushion Support (ACS) and sole support to the good foot and continue using it until the problem has been corrected. As an adjunct to therapy for any abscess that hasn't been opened at the bottom and is going to pop at the top or back of the heel, I cut a piece of animalintex 2º to 6º long, soak it in hot water and wrap it around the coronary band and cover with a bandage. Animalintex expands the foot with moisture, making it much easier to break at the coronary band. However, most of the time opening the abscess at the ground surface early will bypass this complication. In very cold weather if I feel I need to keep the poultice warm, which many times eases the pain, I will put a four hour hand warmer under the bandage. Once the abscess breaks at the coronary band it will clearly define the areas of the foot involved in case you haven't already found them. Just follow the tubules from the top to the ground surface. Those that break out the bulb of the heel have migrated from the toe area along the sole and sensitive frog. This is often the route of least resistance. Note the color, texture and odor of the exudate. This can tip you off as to how aggressive you may need to be with additional treatment. When pseudonoma , proteus or staph is cultured, be very aggressive with broad spectrum antibiotics for at least 10-15 days. An abscess should never be taken lightly. Always treat it as a red alert and work closely with the farrier, who may be able to see the horse more often and provide good information concerning the healing response. I can't stress enough the essence of time. I have been an expert witness on several occasions for suits against veterinarians, farms and farriers concerning cases that began with a single abscess that was not properly diagnosed. Surgery: When antibiotics fail to eliminate the drainage and soreness or exposed sensitive tissue will not cornify, surgery is indicated. Radiographs will also reveal progressive increases in the size and darkness of the lucent palmar lesion. I prefer to perform the surgery in the standing horse, as I find orientation is enhanced when viewing the foot from this position. The procedure is very easy to perform. Make and apply a hospital plate shoe prior to surgery. For all my hospital plate shoes I use a 1/4" aluminum plate and a steel shoe tapped for 1/4" number 20 thread 1/2" bolts. Cutting the inner web close to the edge of the crease often exposes all the sole wall junction that is needed to surgically curette the lytic bone. Trim the foot, clean it up quite well and apply the shoe once the foot is blocked. Prep the area with a surgical scrub. Apply a tourniquet at the fetlock and curette the soft bone. Pack the defect off with Betadine and gauze. Place ACS in the sole and heel area, leaving a window only around the surgery site. This prevents debris from entering the sole area and greatly reduces the amount of gauze that is needed to pack the foot. When applied over the frog it can offer sufficient frog pressure as well. Hospital plates are great protective bandages and most any horseman, even with limited experience, can manage them. I apply a cotton wrap over the hospital plate using Vetrap, then cover it with a layer of Duct tape. Change the bandage every time the plate is removed until the defect is well granulated. This helps prevent unwarranted bacteria invasion via moisture contaminants from the stall. Note the hole needs to be packed in a firm fashion to avoid exuberant granulation tissue from forming. If there is no room for granulation there will be none, and the hole will heal from the bottom to the top. This is one area that I find many struggle with. Failing to pack the defect firmly enough will invariably result in complications. The hole will fill up with granulation within a few hours to days. Though it appears to do quite well, bacteria will be trapped beneath the tissue and the bone margin will not heal. Post Op Care: I change my packs daily using firm, blunt debridement with dry gauze. Between days three and five the bone proper should be covered with a thin layer of pink, firm granulation. If not, most likely a small area of necrosis or sequestrum remains at the site, which should be examined closely with a sterile curette at this time. When I have a very painful case I rocker the belly of the hospital plate, using Equilox to build the surface up to the desired height. I usually like to establish at least a 15-18º palmar angle (PA) once the shoe and plate are on. This will adequately reduce download of the palmar rim into the sensitive sole, which seems to give most cases immediate relief. Once the bone is well covered and the granulation bed is firm and non-sensitive I take the horse off antibiotics and continue to use the hospital plate for at least another 4-6 weeks. Removing the plate too early and using only a pad for protection can cause a serious relapse. Sand, dirt and other debris can get caught between the pad and sole and traumatize the very tender cornified layer of sole. Needless to say, the sooner the soft area of bone is removed the less likely it is there will be complications and the better the prognosis is for a full recovery. I have treated several hundred cases in this fashion over the past three decades and do not remember one case that was not much improved clinically within 24 hours of surgery. Nor do I recall any complications following standing surgery with the shoe on at the time of surgery. However, I am very careful to only use fingertips on my instruments and touch only the tissue being removed with the instruments. Things to avoid: What not to do with indirect puncture cases is just as important as knowing what is best. A very common practice shared by horsemen, farriers, vets is to apply caustic agents to solar abscesses in an effort to dry them up. This practice should be discontinued as it can cause very serious permanent damage to the growth centers, delaying or preventing the area from ever healing. Phenol, 7% iodine and iodine crystals with turpentine should never be used on sensitive tissue. They might have worked in the past on select cases and may seem like a cure all, but I have seen sales yearlings, race horses and extremely valuable brood stock suffer months of protracted, expensive care in an effort to deal with damaged bone that was the result of harsh, caustic agents. Some did not survive. Direct puncture wounds Any foreign object that penetrates the horn capsule is a direct puncture. Bacteria is introduced via the direct route. Direct puncture wounds should be considered an emergency and treated as such until proven otherwise, especially those that involve the sulci of the frog and part of the body of the frog. Causes of deep punctures: The most common objects involved in deep punctures are sharp stones, metal objects, wire, nails, bits of farming equipment and nails or screws. Some of the worst punctures I see are caused by a steel fence post that has rotted off down to the ground, leaving a relatively sharp point that a horse steps on during wet weather. Often times the post will penetrate through the bottom and out through the top of the foot, carrying mud, debris, and grass with it. These cases look to be catastrophic in nature and often result in large bone fragments, but I have not had one case that didn't heal in a favorable fashion and none have resulted in contra limb laminitis. Diagnosis: It is not always easy to find a puncture. Acute lameness is frequently assumed to be the result of an abscess, which means a deep puncture can elude the eyes of inexperienced professionals. As a rule the acutely lame foot will be the result of an abscess, but a direct puncture or fracture should also be suspected. Radiographs will quickly rule out a fracture, and as a rule most fractures are readily visible even when only hours old. If you possess farrier skills, clean the foot up by lightly paring all the sole, frog and sulci and look for small, dark entry holes or fissures. Farriers perform this task daily over and over and are the best person to clean up feet without over trimming. Closely examine all suspected areas. Use hoof testers, but be very gentle. Deep puncture wounds often make the entire foot very sensitive. When a nail, wire or foreign object is still in the foot, tape a piece of wood along the side of the object to prevent it from penetrating any deeper and take radiographs as soon as possible with the foreign object still in the foot. Film taken with the object still in the foot can be invaluable as it will clearly reveal the areas of the foot that are involved with the object. This is very important as tendon, navicular bursa, navicular bone and joint spaces are all life threatening zones. You need to know which ones are involved on day one. When you feel for sure a puncture has occurred but cannot confirm it grossly, radiographs may help identify the affected area. Performing a venogram can also be helpful as the contrast will leak out through the area of sensitivity penetrated. I feel all deep punctures need to be surgically examined at the time of injury. I have been presented with literally dozens of life threatening cases that started off with a very small area of bone or soft tissue involvement, but slowly escalated to life threatening circumstances because more aggressive options, such as surgery, were not pursued. Solar punctures: It is almost impossible for a foreign body to penetrate the sole and not traumatize the bone to some degree. Therefore it is always wise to suspect bone damage with all punctures to the sole area. Note all non-complicated punctures are 100% sound with no drainage and no exposed sensitive tissue within 5-10 days of injury. Otherwise there is bone involvement. When the bone damage is very mild, radiographs made at the time of injury are often non conclusive as small, thin bone fragments are often not demonstrable for a few days. However, a venogram will often reveal a doughnut-shaped lesion, as contrast is trapped under the bone, leaving a lucent center. Radiograph punctures to the sulci or frog with the object in place if possible. Scrub the foot, insert a sterile animal feeding tube (a 19 gauge needle with a bulb on the end) into the puncture track and take two views (remember the law of the circle). Take all the film needed to precisely locate the specific area involved. Note whether or not the bursa, DDF and navicular bones are damaged. If so, this is a life threatening case. Heel area punctures: The goal with this type of puncture is to eliminate DDF action, as you will invade the tendon in order to clean up the navicular bone, and you must protect it while it heals. Make a therapeutic shoe that provides a 90° toe angle and has adequate heel extension bars in at least 3 decreasing sizes: for surgery, the first reset and the second reset. The base of the heel extension should be about the width of the foot. The shoe needs a toe extension plate to prevent the foot from rocking forward too much and a hospital plate to protect the puncture and surgical site. Making the shoe: Using lateral film, create an 80-90º hoof angle position with the ground surface and draw the shoe right on the film. Take rough measurements on the film for the shoe length and heel height. Fabricate an egg bar shoe with extended square heels. Drill 7/32 holes 2 inches on center in the heel of the square heeled egg bar. Use a consistent width between the holes. You can always make extra bars for any horse without taking measurements. Tap the shoe for 1/4" 20 thread bolts. Attach the extended bar, then make a hospital plate from 1/4" aluminum. Drill and tap a shoe for the plate. Only two heel bolts will be needed. Place a 3 - 4" piece of rasp under the toe and weld in place. This stops the foot from going too far forward. The toe of the hospital plate will fit under the lip of the extended toe plate. Secure the plate with the two bolts at the heel. Use a grade A bolt (hard bolt) when attaching the shoe and double nut it. It must not come off. Attach the shoe with bars on and you are ready for surgery. Performing the surgery: Block the foot at the fetlock. Prep the foot with surgical scrub and place a tourniquet on the fetlock. Hold the foot between your knees (wear a farrier's apron) or have a farrier hold the foot. I prefer the former as it helps me stay oriented. Insert a 19 gauge sterile metal animal feeding tube. Leave it in place as you make a clean cut around the needle down to the level of the navicular bone. The top of the hole must be much larger than the bottom. I prefer to remove the entire plug around the feeding tube in one piece. This will include a small section of DDF, exposing the navicular bone. Be careful not to penetrate the joint capsule. Examine and test the surface of the bone with the curette. It may look ok, but many times there will be a loose piece of bone. This must be removed along with any necrotic bone. Pack the hole firmly from bottom to top with gauze infused with 2% Betadine. Place a little extra at the surface so the hospital plate will fit snug, pushing the gauze tightly in the hole to control hemorrhage for the first 3-4 hours. At this time remove the plate and enough gauze to take slight pressure off. If you fail to do this, the extreme pressure you applied to control the hemorrhage will cause unwarranted pain. I usually take a culture sensitivity of the bone fragment and start all cases on a Gentomicin/penicillin combination until the culture comes back. Always apply a Modified Ultimate on the opposite foot, making sure an 18-20º PA has been established. This will greatly aid the prevention of contra limb laminitis. Monitor this foot radiographically as well as with venograms to be assured that laminitis has not been triggered. You need to know this before the horse tells you. Post surgical care: Change the gauze plug daily, being very careful not to disturb the healing, especially the layer that will be attached to the gauze. If there is necrotic bone I will place a small antibacteria impregnated methyl methacrylate bead in the bottom of the hole. It will be pushed to the surface as the lesion granulates from bottom to top. This time release antibiotic works great, especially when a virulent organism has been cultured. It is vital that the hole be packed very tight in an effort to prevent granulation tissue from filling the hole before it has healed at the bottom. This is where most surgeons have a problem. Many of my referral cases over the years have been complicated by the simple failure to prevent exuberant granulation. Normally 5-10 days is required for the bone to be healed and solid granulation tissue cover the bone and tendon defect. It will take an additional 30-45 days for the hole to heal to the surface. At the first reset take a lateral radiograph to determine sole depth and PA. Be prepared to remove the shoe, trim the foot and reapply the shoe with the second bar attached before setting it down. It is very important not to put the foot down with the shoe off, as you do not want to tear the adhesion that has healed at the bottom of the hole. The DDF remains very fragile at this time. The same applies for the second reset 30 days later. Once this shoe is removed, apply a flat shoe with hospital plate and rocker the bottom of the plate using Equilox. This is a nice letdown shoe that gradually increases pressure on the healing tissue, which must be stretched slowly to prevent unwarranted trauma to the newly healed tissue. The prognosis is quite good using this technique provided you do not have a staph resistant organism. When cases are referred from other hospitals you must always be alert to this possibility. The prognosis for deep puncture wounds to the tendon, bursa and/or navicular bone is often considered grave, as many times they are non-responsive even to the most aggressive techniques. However, the tips discussed here compliment aggressive surgical and antibiotic therapy and can improve the prognosis when implemented quickly and efficiently. Heel puncture pain is due to tension on the traumatized and infected DDF and related structures. By creating a 90º hoof angle (40-45º PA) using the shoe described above we can greatly reduce post op pain even when the DDF is involved, as it eliminates all tension. This shoe has been a miracle shoe for me many times, and has saved the lives of several horses that might otherwise have been euthanized due to the cumulative damage incurred from the puncture wound. Protecting the opposite foot from contra limb laminitis is another big part of my success. It is one thing to get the puncture wound out of the woods, but quite another to keep the opposite foot healthy throughout the healing period. By doing so we can greatly increase our chances of success.

49th Annual Convention of the American Association of Equine Practitioners, 2003, New Orleans, Louisiana THE EQUINE FOOT, IN-DEPTH Clinical and Radiographic Examination of the Equine Foot (21-Nov-2003) R. F. Redden Versailles, KY, USA. 1. Introduction Lameness is one of the most frequently encountered problems in equine practice. The foot is involved, either directly or indirectly, in the large majority of lameness cases, as it is the first line of defense for the animal. The health of the foot plays a major role in the fight or flight response that has preserved this noble species for several thousand years. "No foot, no horse" is an adage that has been used across the world for centuries. This indisputable statement encapsulates the importance of a healthy foot; yet we know less about the foot than about almost any other part of the horse, and it is the one piece of anatomy that is dependent on a lay profession for the preservation of its health and function. Worldwide, farriers bear much of the responsibility for maintaining or restoring the health of the horse's foot. For centuries their knowledge and skills have been self-taught, without the benefit of a formal educational program. Their basic job description is to keep the foot healthy by using effective but primitive methods to control the ill effects of horn growth and of wear and tear on the hoof capsule, with little or no information about the effects of these procedures on the sensitive soft tissues, vascular supply, or bone. Veterinarians, on the other hand, have been taught anatomy, physiology, and basic examination techniques; however, they often have limited working knowledge of the foot and little or no farriery skills. Both professions play important and complementary roles. Veterinarians and farriers alike are often asked to examine the foot for a variety of reasons, including developmental problems, gait analysis, lameness exams, and prepurchase exams. In many cases, the opinions that result are as diverse as the backgrounds and areas of expertise of the respective professionals. Combining the knowledge and skills of a competent farrier with the medical and surgical training of the veterinarian greatly enhances the diagnostic and prognostic potential of both clinical and radiographic examinations. Working together also advances the professional standing of veterinarians and farriers. Clinical and radiographic examinations of the foot are simply discovery exercises. Numerous authors have described their methods and techniques in detail. But despite the vast amount of written material on the subject, obtaining meaningful information about the foot remains a challenge for veterinarians and farriers. The key is to use a disciplined, methodical approach that is designed to disclose and define the various normal soft tissue parameters, normal bone anatomy, normal hoof capsule anatomy, and how each component is interrelated. The protocol should also reveal the response of these structures to the forces imposed by ground contact, supporting tissues, and the horse's body weight. Seeking and defining specific pieces of information in a consistent, repeatable manner for each foot, in each horse, greatly enhances the practitioner's understanding and knowledge bank regarding the vast range of normal-which is the real information you want. Whether examining a foot or a radiograph, look for all the normal areas first; what's left over points to the problem you seek. This simple approach effectively helps avoid misinterpretation, a common result of forming an opinion without sufficient diagnostic information; for example, making presumptions concerning the clinical relevance of a radiographic lesion without consideration of the history or physical findings. 2. Clinical Examination Regardless of the purpose of the examination, the physical exam is the most important aspect of evaluating the equine foot. The extent and nature of the exam must be tailored to the situation, however, taking into account the demands of the client. Good horsemanship, a good working knowledge of the foot, and some basic farriery skills are other prerequisites for a proper and safe examination. A complete history which clearly describes the complaint complements the physical exam and adds context to any clinical findings. Listen to the history as you examine the foot, but do not jump to conclusions nor be swayed by the opinions or conclusions of others. Visually inspect the foot before picking it up, and feel the hoof capsule with your hands, noting its many unique characteristics. Although certain generalities can be made, there is a range of normal for hoof characteristics which is influenced by the horse's breed, age, environment, and use. Considering the variability imposed by these factors, the range of normal can be very broad. The importance of understanding the variability in structure of the healthy equine foot lies in identifying subtle deviations from normal which are of clinical significance. These early distortions are easily missed if the normal parameters for a horse of that breed, age, environment, and use are not appreciated. The following example details the requirements for adequately defining normal for a particular horse. Let us consider the forefoot of a 3-yr-old Thoroughbred horse, bred for racing but used as a noncompetitive riding horse in central Kentucky. That foot would probably have the following characteristics: a hoof angle between 50 degrees and 58 degrees, and a heel angle perhaps 15-20 degrees less; a relatively straight wall (i.e. no flaring, dishing, or bulging); width approximately 5 in. (measured at the widest point); mass of digital cushion 2-3 in. (discussed later); hoof wall thickness of 3/8-1/2 in. at the toe and the bars;a hoof wall perhaps one-half as thick at the quarters; a sole with a moderate cup (3-5 mm in height); a frog in contact with the ground (although it would also be normal for this horse to have a relatively flat sole, i.e., little or no cup, and a large, flat frog); and a hoof wall with a solid appearance and a glossy surface. We must leave behind the "ideal" of the normal equine foot depicted by artists in veterinary and farriery texts for the past century or more. Hoof angles and heel angles do not match on any normal foot. And the "ideal" toe angles of 45 degrees for front feet and 50 degrees for hind feet are far from normal as they do not match the pastern angles. One must become a connoisseur of horses' feet and begin to build a personal data bank of normal for particular breeds, age groups, environments, and uses. The Seat of Pain When dealing with a lame horse, most authors consider the physical exam simply a means of reaching a diagnosis, i.e., of giving the problem a name. While this approach certainly satisfies one of the goals of the exam (to identify the problem), years of experience as an equine podiatrist have made me very aware that most owners want a fix and could care less about a diagnosis. As I'm going through a lameness work-up, I focus on identifying the area(s) of pain rather than specific pathology. Dividing the foot into two halves, front and back, then dividing further into quadrants (medial and lateral, front and back) offers a simple way of isolating the specific area of inflammation or seat of pain (Fig. 1, A and B). Figure 1. (A) Imagine dividing the foot in half. Figure 1. (B) Then in quarters. Dividing the foot into four basic zones helps me determine whether the components in each zone fit within the range of normal for that particular animal. With my understanding of radiographic anatomy (again bearing in mind the range of normal), I visualize the bone and associated soft tissues superimposed over the hoof (Fig. 2). Any finding that falls outside the range of normal is considered relevant, as it contributes to the dysfunction of the foot as an integrated unit and thus probably plays a role in the current lameness problem. Simply cleaning the ground surface of the hoof can reveal areas of possible concern. (Fig. 3). Each of these areas is a map of a potential problem: examine each thoroughly before moving on. Remember to look for all the normal areas first, and what is leftover often points to the problem that you are attempting to identify. Figure 2. Visualize the bone and associated soft tissues superimposed over the hoof. Figure 3. Simply cleaning the ground surface of the hoof can reveal areas of possible concern. After a quick visual exam, I palpate, using thumb pressure to locate areas of increased sensitivity along the coronary band, the bulbs of the heel, and even over the sole on thin-soled feet. Hoof testers should be used with great care, because inappropriate use causes the horse to anticipate further pain and show an exaggerated response to even light pressure. When applying hoof testers, use a very soft touch. All that is needed to identify areas of increased sensitivity is just enough pressure to cause slight movement of thin horn (e.g., the sole in a thin-soled horse). Also be aware of how you are holding the horse's leg. If, by positioning the limb between your knees so that you are comfortable, the horse is made uncomfortable, you may elicit a response that has nothing to do with the foot. It is easy to abduct the limb too far when placing the horse's lower limb between your knees. To avoid this situation, note where the horse's body in relation to the foot when you first pick up the leg. Try to maintain that orientation when placing the limb between your knees-i.e., put yourself where the foot is or have someone hold the limb for you (Fig. 4 A-D). 4A 4B 4C 4D Figure 4. (A) Note relaxed position of foot. (B) Position yourself to horse’s relaxed position. (C) Avoid abducting limb for your comfort. (D) Proper stance when using hoof testers. The Failing Structure Distinguishing the abnormal area(s) allows me to identify which part(s) of the system is failing and affecting the integrity of the whole. Simply recognizing the failing structure(s) as the primary problem-the underlying cause of any secondary bone and/or soft tissue disease-gives new meaning to the discovery exercise and places new emphasis on the findings. Following is an example of this concept. Race horses, or in fact any speed horse, with less than 10 mm of sole, zero or negative palmar angle (the angle of the palmar margin of PIII relative to the ground surface), loss of cushion mass (see below), obvious medial-lateral imbalance, and a history of foot pain are often diagnosed with navicular disease, pedal osteitis, or bruised feet. Any of these diagnoses may be correct and the associated pathology may be contributing to the present lameness. However, more important is the fact that the essential protective function of the hoof capsule and the shock-absorbing features of the cushion network are seriously compromised, and the cumulative effects of these failing systems are now of paramount importance. The "diagnosis" in this case is thus, multifaceted. However, it can be simplified by describing the situation as one of mild, moderate, or excessive horn loss associated with mild, moderate, or excessive compromise of the soft tissues. Instead of being focused on a medical diagnosis (which may well be challenged by another veterinarian or farrier) and a quick fix to satisfy the immediate demands of the client, identifying the failing systems allows the focus to be placed on a solution, which in this case involves restoring the much-needed hoof mass. Figure 5. Use thumb and finger to guesstimate depth of digital cushion. The depth of the digital cushion can be estimated by placing your thumb in the shallow depression between the heel bulbs and placing the index finger of the same hand on the center of the frog (Fig. 5). In light breed horses with strong, healthy heels, the distance between thumb and fingertip is in the range of 3-3.5 inches. 6A 6B Figure 6. (A) Typical Thoroughbred hind foot. Note coronary band relationship with the ground. (B) Front foot, American Saddlebred. Growth ring patterns, coronary band conformation, heel tubule angles, toe angles, and horn quality offer insight to sole depth, palmar angle, and overall state of balance. When this distance is well short of the normal range, one can expect to see evidence of soft tissue compromise radiographically. This simple observation, coupled with noting the slope of the coronary band relative to the ground, also allows an estimation of sole depth and palmar angle. Figures 6 and 7 illustrate how these observations correlate with radiographic findings. Note the difference in slope of the coronary band, angle of the horn tubules at the heel, and depth of cushion between the two horses (Fig. 6A, 6B). Compare these photographs with lateral radiographs of the same feet (Fig. 7A, 7B). 7A 7B Figure 7. Radiographs of feet shown in Figure 6. (A) Note negative 6 degree palmar angle. (B) Note H-L zone and positive 6 degree palmar angle. Incidentally, in my experience hind feet with a zero or negative plantar angle (wings of PIII level with or lower than the apex) are often associated with pain in the lumbar area or croup. Back pain in these horses frequently diminishes once heel mass is improved and a normal plantar angle is restored. Other Notes It is necessary to remove the horse's shoe in order to thoroughly examine the foot, especially when the primary problem cannot be identified with the shoe on. At the very least, the shoe prevents examination of the bearing surface of the wall, the terminal laminae, and the perimeter of the sole. However, care must be taken when pulling shoes. In feet with fragile walls, raised nail clinches, or a special shoeing package, the shoe is best removed by a competent farrier unless you have considerable farriery expertise. A good sense of smell can be a valuable aid in examining the foot. We all know the smell of a foot with thrush. But your olfactory sense can also help you identify digital sepsis. With experience, it is even possible to distinguish soft tissue necrosis from septic processes involving bone. Again, attention to detail is the key to refining one's examination skills. Key Points physical examination is the most important part of evaluating the foot develop a methodical approach, and use it every time look for normal first (bearing in mind the range of normal for that horse's breed, age, environment, and use); what's left over points to the problem you seek localize the seat of pain to one or more quadrants visualize the underlying bone and associated soft tissues when looking at the hoof think in terms of identifying the failing structure(s) 3. Radiographic Examination Much has been written about specific views for imaging the equine foot. Almost without exception, the primary objective of these views is examination of bone (PIII, navicular bone, and/or coffin joint surfaces). Little or no attention is paid to the soft tissues within the hoof capsule. This approach seriously limits the scope and accuracy of the radiographic examination and thus its value in developing an action plan for managing lameness involving the foot. The coffin bone is suspended within its protective shell by soft tissues whose health is crucial to the structural and functional integrity of the foot as a whole. Dysfunction is inevitable when any of the soft tissues are compromised or strained beyond their normal limits. Over the many years I have worked as an equine podiatrist, I've come to appreciate the fact that soft tissue pathology is present to some degree in every footsore horse. Thus, evaluation of the soft tissue zones within the hoof capsule is an extremely important part of radiographic examination of the foot. Evaluating the Soft Tissues While it is true that radiography is relatively poor at imaging soft tissues, a lot of information about the soft tissues within the foot can be gleaned from good quality radiographs taken with soft tissue detail in mind (discussed in the next section). At the very least, the width of the corium and horn can be accurately measured for both hoof wall and sole, provided the outer surface of the dorsal hoof wall is delineated using radiopaque material and the ground surface is defined either by the shoe or by a radiopaque marker in the surface of the positioning block. I measure the following indices on all routine lateral films (Fig. 8). Sole Depth Sole depth is defined as the vertical distance between the palmar/plantar margin of PIII and the outer surface of the sole. It is routinely measured at the distal tip, or apex, of PIII (Fig. 8). A normal, healthy foot has a sole depth of at least 15 mm. Based on venographic studies in a wide variety of horses, I consider a sole depth of less than 15 mm to be clinically significant. In a normal foot, the papillae of the solar corium appear to need a space of at least 10 mm between the palmar surface of PIII and the cornified layer of the sole for adequate vascular filling; and at least 5 mm of cornified sole is required to protect the solar corium. Venograms in horses with a sole depth <15 mm show solar papillae that are bent, compressed, or even absent. This distortion or compression surely inhibits sole growth, creating a vicious cycle of thin, tender soles. Figure 8. Standard low beam, soft tissue view with opaque wall marker and ground surface marker offers a consistent means of accurately measuring soft tissue parameters. Progressive farriers often use this view as a blueprint for pathological shoeing. Dorsal Horn-Lamellar Zone Width Dorsal horn-lamellar (H-L) zone width is defined as the distance between the dorsal surface of PIII and the outer surface of the dorsal hoof wall, measured with the ruler perpendicular to the dorsal surface of PIII (Fig. 8). Dorsal H-L zone width can be measured anywhere along the dorsal face of PIII, but I routinely measure it at two locations: just below the extensor process, and near the distal tip of PIII. I record the measurements as proximal/distal (e.g. 15/15, meaning that the dorsal H-L zone is 15 mm at both locations). In a normal adult foot, the measurements should be the same proximally as distally (i.e. both numbers are identical). In the immature foot, the proximal value may be greater than the distal value. Normal dorsal H-L zone width in Quarter Horses, Thoroughbreds, and most other light horse breeds is 15-16 mm. In Standardbreds, the H-L zone normally is a little wider, averaging 20 mm. Normal H-L zone width for Warmbloods depends on the size of the foot; in many cases it is similar to that for light breeds. Once again, an appreciation of the range of normal for that type and size of horse is essential for accurately interpreting this area. 9A 9B Figure 9. (A) White line disease. Note the lucent lesion starts at the ground surface of the wall, has a very irregular border, often is superimposed over the bone, and often contains dirt, stone, and other debris. (B) Chronic laminitis. The lucent lesion is within the laminae and stops abruptly at the innersole margin even when penetration has occurred. The sides of the lesion are smooth and the proximal distal border of the lesion has a smooth radius. Capsular rotation is the only common finding. Significant information can be gained by using the soft tissue parameters as a measurable unit to describe displacement. Dorsal H-L zone width is an important measurement, as this zone widens in conditions that affect the laminar corium, laminar attachments, and wall thickness. Laminitis and white line disease are two common and clinically important conditions in which the dorsal H-L zone widens. Widening as one moves down the hoof wall from proximal to distal (i.e. H-L zone wider distally than proximally) may also be seen with other conditions. This assessment, when used with the palmar angle (Fig. 9B), provides a meaningful way to identify and describe displacement of PIII. The conventional method of identifying and quantitating PIII rotation is inaccurate and misleading. The fact that the hoof capsule can be substantially altered by the farrier reduces evidence of rotation. Drawing straight lines along the irregular hoof wall and irregular face of PIII is subjective at best and the wall is constantly being altered by growth and the disease process. Therefore the whole basis of this measurement (PIII-hoof wall angle) is seriously flawed. Traditionally measuring capsule rotation as a means to diagnose laminitis has also created the misconception that simply rasping the horn wall back to a parallel relationship with the face of PIII is an effective means of treating the syndrome. Very serious life threatening lamellar swelling often occurs without even a subtle hint of rotation. Therefore the significance of rotation as it relates to pathology is questionable. On a good soft-tissue-detail lateral film, one can readily identify the linear radiopaque zone that equally divides the H-L zone in most normal horses. For example, in a foot with a dorsal H-L zone width of 15 mm, each zone measures 7.5 mm. When widening of the dorsal H-L zone is found, evaluation of the width of each zone is important, as it can provide diagnostically and prognostically valuable information. For example, the lamellar zone widens in laminitis, (Fig. 9B) whereas it is the horn zone that widens in white line disease (Fig. 9A). (Note: The outer surface of the dorsal hoof wall must be accurately represented by radiopaque material in order for measurement of the horn zone to be accurate.) Coronary-Extensor Process Distance Coronary-extensor process (C-E) distance is the vertical distance between the most proximal extent of the outer hoof wall and the top of the extensor process of PIII (Fig. 8). In most normal horses it is 0-15 mm. The C-E distance can be accurately measured only if the radiopaque marker on the dorsal hoof wall extends all the way to the proximal limit of the wall. This measurement can be important in confirming displacement of PIII, provided a baseline is established for that horse prior to, or at the onset of the disease process. Palmar Angle Palmar angle refers to the angle of the palmar or plantar margin of PIII relative to the ground surface. It can be measured relative to (a) the ground surface of the hoof capsule, or (b) the ground itself. In the first instance, (a), the angle is largely unrelated to the mechanics of the shoe or other device that may be attached to the foot. It provides information about the structural integrity of the soft tissues in the heel area, especially the digital cushion. With the second method, (b) the palmar angle is also indicative of the mechanical effect of any shoe/device that is attached to the foot (Fig. 18A). In most healthy feet with strong heels and a robust digital cushion, the palmar angle is positive, meaning that the wings of PIII are higher than the apex (Fig. 7B). As with most other indices, the range of normal for palmar angle is dependent, in part, on the horse's breed. Breeds that tend to have upright hooves typically have higher palmar angles than breeds with naturally lower hoof angles. The shoeing package can also affect the palmar angle, which must be borne in mind when measuring palmar angle relative to the ground. A high palmar angle (relative to the range of normal for that breed) may be found in horses with club feet, laminitis, and certain other pathological conditions. A negative palmar angle (wings of PIII lower than the apex) indicates substantial loss of structural integrity in the heel area, a situation that can usually be predicted simply by looking at the foot and estimating the depth of the digital cushion. Qualitative Assessment In addition to these measurements, a high-quality radiograph taken at a soft exposure (see below) can reveal variations in radiodensity within these soft tissue zones. For example, even in a normal foot there is a subtle yet distinct change in radiodensity between the laminar corium and the cornified inner layers of the dorsal hoof wall. Evaluating the soft tissue zones around PIII is particularly important in the diseased foot, as congestion, edema, or accumulations of inflammatory exudate or gas can alter the radiodensity of the tissue, in addition to altering its thickness. Thus, a lot of useful information regarding the soft tissues of the hoof can be obtained, either directly or by inference, if one only looks for it. This approach is particularly useful in the lame, footsore horse that has no radiographic abnormalities on "standard" foot films (i.e. no obvious bone pathology). Careful evaluation of the soft tissue zones surrounding PIII often reveals interesting details to the trained eye. As with clinical examination, it is important to develop an eye for fine detail and an appreciation for the range of normal (relative to breed, age, environment, and use) in order to get the most out of a radiographic examination. Exposure Settings The coffin bone differs greatly from other bones in the limb, in that it is surrounded by a dense, cornified shell whose thickness, density, and water content affect radiographic detail of the bones and soft tissues it encases, and even of the capsule itself. These characteristics of the hoof capsule must be factored in to the radiographic technique. Another unique feature of PIII that must be considered is its shape. The thickness and density of the bone differs markedly from proximal to distal, the bone being very thin and lacelike at its palmar/plantar margin. In certain pathological conditions, this area can become even less radiodense. The radiographic technique must factor in this normal variation in bone thickness and density. The coffin bone cannot be thoroughly evaluated from just a handful of films, no matter how good the films. Adequately imaging the navicular bone and adjacent structures presents yet another challenge. Not only are the navicular bone and related structures encased within the hoof capsule, they are surrounded on three sides by PIII (and, on some views, overlaid by PII), so superimposition of bone also must be factored in to the radiographic technique. Thus, thoroughly examining all of the structures within the foot requires several views and different exposure settings, each one tailored to best image the structure of primary interest. 10A 10B Figure 10. (A) This soft exposure has farrier interest; it clearly defines soft tissue parameters as well as soft tissue lesions. Note opaque lesions proximal to the navicular bone. Palmar angle of navicular bone can be measured from this view as well. (B) This 65 degree DP was taken with a very soft exposure, clearly defining the thin margin and multiple cystic lesions. Selecting Exposure Settings For any radiographic view, the ideal exposure setting will depend on the equipment used (x-ray machine, screens and film, processor, etc.), hoof mass, and the structure of primary interest. I use the terms soft, medium, and hard to describe the exposure settings I select for a particular view, depending on which tissue I am most interested in evaluating. (Note: Specific values for kVp and mAs will depend on the equipment used and the size of the foot being examined, so it is not possible to provide even general guidelines here.) Soft exposures are for nonbony tissues, such as the horn and corium of the hoof wall and sole, and for the palmar margin of PIII (Fig. 10A). A good soft exposure can reveal differences in radiodensity within the hoof wall which allows differentiation between the laminar corium and the keratinized layers of the hoof wall. When looking for abnormalities at the palmar margin of PIII on the 65 degree dorsopalmar (DP) view, a very soft exposure is needed. If the perimeter of PIII cannot be seen without the use of a hot light, the view should be retaken at an even lower mAs (Fig. 10B). Medium and hard exposures are used when the structure of interest is bone. Medium exposure is used for bony structures of moderate density or thickness, such as the body of PIII, and for articular surfaces. Hard exposure is used for denser bone or superimposed structures, in particular the navicular bone. I always use a 6:1 parallel grid when using a hard exposure setting. As this approach illustrates, it is important to tailor the settings to the goal of the examination-to the structure you are most interested in evaluating. "Underexposed" is a relative term. What may seem grossly underexposed to others may be the perfect exposure to show soft tissue detail within the hoof wall or sole, or the palmar margin of PIII. Unless taking radiographs simply to guide farriery decisions, I take at least two exposures for each view: one soft and one bone detail (medium or hard) exposure. Soft tissue detail is essential, as the nonbony structures surrounding PIII are an integral part of virtually every foot problem. Factors Affecting Image Quality The diagnostic value of any radiographic examination is determined by the capability of two basic factors: the equipment and the examiner. The skills and knowledge of the examiner are as important as the choice and maintenance of the equipment (x-ray machine, cassettes, screens, film, developing and marking systems, positioning blocks). Not only does the examiner need a good working knowledge of clinical and radiographic anatomy of the foot (including an understanding of the range of normal), s/he needs good radiography skills, from a basic grasp of the geometry of radiation to experience with taking routine radiographic views. Good horsemanship skills are also important. A disciplined, methodical protocol, designed to provide as much information as possible, is of primary importance if one is to get the most diagnostic value from radiographic examinations. Techniques for ensuring high quality radiographs of the equine foot are described in detail elsewhere1 and will only be summarized here. Several different factors can affect image quality, and thus limit the amount of accurate information you can obtain from your films: Preparation of the foot-thoroughly clean the foot of all debris, paying particular attention to the frog sulci. Beam positioning-the focal area of the primary beam is a zone 4-cm in diameter in the center of the beam; using the light guide or laser pointer, focus the beam on the area of primary interest. Beam-film relationship-make sure the cassette is perpendicular to the beam on all views; image distortion occurs whenever the film is not perpendicular to the beam. Subject-film distance-aim for a zero subject-film distance (i.e. cassette in contact with foot) to minimize magnification. Source-image distance (SID)-use a consistent SID; measure the distance each time, rather than 'eyeballing' it. Hoof mass-always take into consideration the size of the foot; make separate technique charts for different sized feet, from foal to draft horse. Radiopaque markers-use markers to clearly and accurately delineate the dorsal hoof wall (lateral views) and, if the horse is unshod, the ground surface (lateral and DP views). Screens and film-use appropriate film-screen combinations, and replace defective screens and cassettes. Developing solution-use developer at a consistent temperature set for your technique chart (contrast varies by approximately 10% for every 1 degree F difference); replace weak developing solution. Film marking-mark each film clearly and accurately; it is a permanent record and your "signature" to colleagues and clients. Points 3 and 4. Beam-subject-film positioning is every bit as important as the exposure settings used. No matter how good the contrast and detail on the film, the radiograph may be noninformative or misleading if the structures of interest are distorted or obscured because of poor positioning. To minimize image distortion, the cassette must be perpendicular to the beam. Distortion will occur whenever the beam does not strike the film perpendicularly. To minimize magnification, the cassette must be in contact with the foot (i.e. zero subject-film distance). Point 5. Several authors recommend a SID of 40 in. in order to minimize image magnification. I use a SID of only 24 in. for all radiographs. I have found that the amount of image magnification is negligible between these two SIDs (40 in. and 24 in.), and by using the shorter SID I can use lower exposure settings, thus maximizing the longevity of my x-ray machine and minimizing radiation exposure of personnel. In my experience, beam-subject-film positioning is much more important than the length of the SID in minimizing magnification and image distortion. Point 7. Let me reiterate how important it is to accurately delineate the dorsal hoof wall with radiopaque material for every lateral foot film. Even at a very soft exposure, you cannot know exactly where the outer surface of the hoof wall is, so you cannot accurately measure dorsal H-L zone width unless the surface of the wall is marked. To paraphrase Murphy's Law, it's on the cases you don't think you'll need it that you'll most wish you'd done it! Furthermore, having the surface of the hoof wall outlined on every lateral film you take will soon train your eye to recognize subtle increases in dorsal H-L zone width even before you get out your ruler. Almost without thinking about it, you'll have added significantly to your range-of-normal data bank for this particular soft tissue zone. The Shoe It is not always necessary to remove the horse's shoe for radiographic examination of the foot. Whether or not to remove the shoe depends on the purpose of the examination. In fact, taking routine lateral and DP views with the shoe on can provide valuable information regarding the current shoeing strategy, such as balance, breakover, and loading. However, leaving the shoe on limits the extent of the physical examination. Depending on the shape, style, and fit of the shoe and horn growth since application, the shoe may obscure certain structures of interest on 45 degree and 65 degree DP views and 65 degree DP-45 degree lateromedial oblique views. The shoe may be superimposed over the palmar margin or wings of PIII, the coffin joint, and/or the navicular bone. In addition, scatter of radiation from the shoe can adversely affect image quality. (Fortunately, most of these structures of interest can be accurately imaged using other views, with the shoe on, without superimposition of metal or scatter of radiation.) Routine Views "Standard" views of the foot have been suggested as a guideline for practitioners. In my experience they are of limited value, except as screening tools. They are inadequate alone for thorough radiographic examination of the foot. That is because beam orientation, positioning, and exposure settings should be selected in each case based on the purpose of the examination-the reason for performing the examination and the radiographic characteristics of the structure of primary interest. Below are descriptions of the routine views I take: particular orientations and exposures that I use in most radiographic examinations of the foot. But first, it is important to reiterate that the value of the radiographic examination hinges on how well the physical examination was performed. Physical examination is the single most important aspect of examining the equine foot. With very few exceptions, the objective of the radiographic examination is simply to confirm the findings or suspicions of the physical examination. Relying on radiographic findings in place of a thorough physical examination and without consideration of the history carries the risk of misinterpretation and error, which can be costly. Lateral When the principal item of interest is PIII in relation to the hoof capsule and the associated soft tissue zones, the beam should be centered 1/2 - 3/4 in. above the bearing surface (i.e. close to the palmar margin of PIII), midway between toe and heel (Fig. 11). To accurately measure sole depth, distal H-L zone width, and palmar angle, the beam must be centered as close to the palmar margin of PIII as possible. These indices cannot be accurately measured when the beam is centered at or near the coronary band. In most light horse breeds shod with a normal shoe, the palmar margin of PIII is approximately 1/2 - 3/4 in. above the bearing surface of the wall. In Tennessee Walking Horses and other breeds shod with a raised package or with excess length of hoof wall, the beam must be raised accordingly. Before taking the radiograph, ensure that the beam is horizontal and perpendicular to the sagittal plane of the foot, the cassette is positioned so that the entire foot is included and is centered on the film, and the cassette contacts the foot and is perpendicular to the beam. (Note: Lining up the heel bulbs by eye as a way of orienting the beam will result in a slightly obliqued view if there is even a slight disparity in the heels, as the beam will not be perpendicular to the sagittal plane of the foot). Figure 11. For the soft tissue low beam view, the positioning block should be of sufficient height to have the center beam strike the hoof horizontally 0.5-0.75 in above the bearing surface of the wall. Using two blocks assures more accurate information concerning balance and facilitates examination of the lame horse that is unable to stand on one block. If the positioning block is an appropriate height and the x-ray beam is horizontal and centered between the shoe and the palmar margin of PIII, both branches of the shoe will be precisely superimposed (i.e. only one shoe branch is seen). If the foot is balanced lateromedially, both wings of PIII will also be precisely superimposed. When the shoe branches are superimposed but the wings of PIII are not (i.e. one shoe branch but two wings are seen), it indicates lateromedial imbalance, which can be confirmed on the DP view. (Note: If the palmar margin of PIII is >1 in. [25 mm] above the block, it may be necessary to raise the beam a little to accurately assess lateromedial balance on the lateral view.) If the shoe branches are not superimposed, it indicates a positioning problem, e.g. the beam is not horizontal and/or it is centered too high on the foot. Sole depth, palmar angle, and dorsal H-L zone width cannot be accurately measured on such a film. The two exposures recommended for this view are soft and medium. The soft exposure is a "farrier-interest" view, as the information it provides can be of great use to farriers, as well as to veterinarians. Provided the dorsal hoof wall is delineated along its entire length with a radiopaque marker, this view allows accurate assessment of sole thickness, cup depth, medial-lateral balance, digital breakover, dimensions and radiodensity of the H-L and C-E zones, and palmar angle. In addition, it reveals the profile of PIII, and even bone detail along the thin palmar margin. I use this view in 100% of cases, as it is a blueprint for all therapeutic trimming and shoeing strategies. Commonly diagnosed syndromes such as laminitis (with lamellar zone swelling and/or PIII rotation) and white line disease are easily confirmed with this view. Other lesions that may be evident on this view include fractures in the wing of PIII, proliferative bone changes along the dorsal face of PIII, and the osteoclastic results of keratomas and other space-occupying masses within the hoof wall. Raised lateral For a lateral view of the navicular bone or coffin joint, the beam should be centered just below the coronary band and a little closer to the heel-i.e. directly over the navicular bone or coffin joint. Other positioning factors are as described above for the lower lateral view. (Note: On raised lateral films, neither the shoe branches nor possibly the wings of PIII will be superimposed.) The exposures recommended are medium and hard (using a grid). The medium exposure is best for evaluating the coffin joint. The hard exposure allows evaluation of the navicular bone and surrounding area, including the impar space. By providing a good short-axis view of the navicular bone, this orientation and exposure setting can reveal calcification or avulsion fractures associated with the impar ligament or the navicular suspensory ligaments. Dorsopalmar view When the principal item of interest is PIII in relation to the hoof capsule, the beam should be centered at the toe, 1/2 - 3/4 in. above the bearing surface of the wall. Ensure that the beam is horizontal and parallel with the sagittal plane of the foot, the cassette is positioned so that the entire foot is included and is centered on the film, and the cassette is perpendicular to the beam. For routine DP views, the cassette is placed behind the foot, as close to the heels as possible, while making sure the cassette remains perpendicular to the beam. This approach produces a somewhat magnified yet relatively undistorted image. The exposure recommended for this view is soft to medium. This exposure allows evaluation of PIII in relation to the hoof capsule, the hoof capsule in relation to the ground, and thus lateromedial balance. It also allows accurate evaluation of sole depth. These films are farrier-interest views. Figure 12. This DP view was made with the beam centered over the navicular bone, horizontal to the ground, using a hard exposure and 6:1 grid. The DP 45 degree oblique and the flex lateral taken with the same exposure and grid are also complementing views, and likewise, are not limited by the presence of the shoe. Figure 13. Positioning for the 65 degree DP view. This positioning block ensures that the cassette is perpendicular to the beam, and thus, minimizes image distortion. Raised DP The raised DP view is an excellent projection for evaluating the navicular bone. For this view, the beam is raised approximately 2 in. (depending on the size of the foot) so that it is centered over the navicular bone. The beam is horizontal and all other positioning factors are as described for the lower DP view. The exposure recommended is hard, using a grid (Fig. 12). If a problem involving the coffin joint is suspected, the raised DP view can be taken at a medium exposure. This view and exposure setting may also reveal fractures through the body or wing of PIII, proliferative bony changes along the palmar margin of PIII, side bone, extensor process lesions (e.g. cysts), and lytic lesions associated with PIII sepsis. 65 Degree Dorsopalmar View This view is the one most commonly used by clinicians to evaluate the distal margin of PIII and the navicular bone. Many practitioners set up for the 65 degree DP view by placing the cassette in a protective sleeve (tunnel) on the ground, having the horse stand on the tunnel, and angling the beam approximately 65 degree to the ground/cassette. While it is convenient, this practice results in significant distortion of the image, as the beam does not strike the film perpendicularly. Distorted images of the navicular bone carry an inherent risk of misinterpretation, as they do not accurately represent the architecture of the bone. For example, the normal radiolucent areas within the medullary cavity may appear elongated, widened, or otherwise misshapen on a distorted 65 degree DP. 14A Figure 14. (A) This radiograph was taken with the bone placed in the positioning block shown in Figure 13 (65 degree DP perpendicular beam to film relationship). 14B (B) This radiograph was taken with conventional 65 degree DP tunnel projection. Note the measurable distortion that occurs when the beam is less than perpendicular to the film. It is far better to support the foot on a positioning stand which allows the cassette to be placed perpendicular to the ground and thus to the horizontal x-ray beam (Fig. 13). While some amount of magnification is inevitable, this method ensures that the cassette is perpendicular to the beam, so image distortion is minimal (Fig. 14). Another potential source of error is failure to adjust for the angle of the navicular bone relative to the ground surface of the foot. Depending on the horse's conformation and on how the 65 degree DP view is taken (e.g. foot loaded or unloaded), the navicular bone may be more upright or more tilted back than expected, which will affect its appearance on the 65 degree DP image. It is worth checking the navicular bone angle on a lateral view (with the foot in position for the 65 degree DP) before taking this view, as some adjustment in hoof position may be needed to get a true dorsopalmar view of the navicular bone. For example, it may be necessary to take a 45 degree DP, rather than a 65 degree DP, to accurately image the navicular bone. It is possible to get reasonably good detail on 45 degree and 65 degree DP views without removing the shoe, despite the scatter of radiation from the shoe. Often, however, the shod foot cannot be adequately cleaned and the branches of the shoe partially obscure the navicular bone and the wings of PIII. Therefore, it is always best to remove the shoe for these views. For evaluation of the navicular bone, the beam is centered over the navicular area and a hard exposure is taken using a grid. A medium exposure allows evaluation of the coffin joint and the body and wings of PIII. A very soft exposure is indicated for identifying fractures at the distal margin of PIII (solar margin fractures) or soft tissue changes in the toe region. Remember that the bone at the distal margin of PIII is very thin and fenestrated with numerous blood vessels, and the mass of hoof the beam must pass through at this level is relatively small, so a very soft exposure is needed to properly evaluate this area. Note - For 45 degree and 65 degree DP views, it is very important to clean the foot and distal pastern thoroughly, paying special attention to the heels and the frog sulci, to prevent superimposition of debris over the navicular bone and coffin joint. Even with a well-positioned, high-detail film, failure to thoroughly clean the foot of all debris makes it difficult to properly evaluate these structures. In addition to thoroughly cleaning out any deep recesses in the frog, I trim the margins of narrow, irregular frog sulci, especially when the frog is very hard and dry. These narrow crevices create an air density over PIII and the navicular bone on 45 degree and 65 degree DP views that can be mistaken for a fracture line. Packing the frog sulci and bar area with Play Doh or similar material is a common practice when taking 65 degree DP views. I do not pack the foot with anything, as the packing material creates a subtle shadow on the film which interferes with my interpretation of the underlying area. I much prefer the greater detail of an unpacked foot. (To test this yourself, pack only one half of the foot, take a 65 degree DP, and compare the detail between the packed and unpacked sides of the foot.) Another reason I do not pack the foot is because the farrier in me wants to see the outline of the frog and its sulcus-features I am already familiar with from having examined the foot thoroughly before taking radiographs. 65 Degree DP-45 Degree Lateromedial Oblique When taking 65 degree DP-45 degree lateromedial oblique views, beam position may depend on the structure of primary interest. For example, the beam is centered a little higher for the navicular bone than for lesions in the toe region. Use a soft exposure for the wing of PIII (Fig. 9). This exposure can also be used to evaluate horn and soft tissue lesions in the quarter area, such as quarter cracks, bar cracks, gas-producing abscesses, and puncture wounds. A medium exposure is suitable for evaluation of the articular margins of the coffin joint. Use a hard exposure (with grid) to evaluate the wing of the navicular bone. This exposure also allows good visualization of the medial or lateral margin of the impar ligament attachment. Calcified lesions within the navicular ligaments, bone spurs, and medullary and cortical changes are all clearly demonstrated on this view. Flexed Lateral The positioning block I use for 65 degree DP views can also be used to take a flexed lateral. This view is useful in extremely lame horses that cannot bear weight on the foot. It is also useful for evaluating the coffin joint and navicular area in other horses, as flexing the digit opens the dorsal and palmar aspects of the joint. The shoe does not limit the information gained from this view unless is poses a positioning problem. Navicular Views Detailed discussion of the navicular bone and associated structures is beyond the scope of this paper. However, some general comments are in order. Perhaps most important is that no one view is adequate for proper examination of the navicular structures. Several views are required to adequately evaluate this part of the foot. In my experience, not only is the 65 degree DP inadequate on its own, it is perhaps the least informative view and the one most prone to misinterpretation, for the reasons discussed above. I've found the raised DP view, using a hard exposure (with grid), to be a very informative navicular view, provided the angle of the navicular bone is taken into account. This view can reveal abnormal radiolucencies involving the cortex and/or medullary cavity. A 45 degree DP (hard, with grid) complements the raised DP by allowing better evaluation of the wings of the navicular bone. The flexor surface, distal margin (impar ligament attachment), and proximal margin can be evaluated on a raised lateral or flexed lateral view, again taken at a hard exposure with a grid. Oblique DP views can also be useful for revealing navicular fractures. The skyline (palmar proximal-to-distal) view has been advocated by some authors as the view to best image the flexor surface of the navicular bone. It can be a very useful view when taken correctly, as it can show cortical lesions along the flexor surface, particularly within the sagittal ridge. (Fig. 15) It also allows evaluation of the medullary cavity and the relative thickness and density of both cortex and medullary cavity, which can change with the stage of navicular syndrome. In addition, lesions within the deep digital flexor tendon as it runs over the navicular bone may be apparent on this view, particularly if the lesion is calcified. However, as with the 65 degree DP view, the skyline is easily misinterpreted if the image is distorted by poor beam-film positioning (i.e. when the beam does not strike the film perpendicularly) and if the angle of the navicular bone is not taken into account. Unless the angle of the beam precisely matches the orientation of the navicular bone, it is not the flexor surface that is brought into relief, but the proximal or distal palmar margin of the navicular bone. Figure 15. This radiograph was taken with the foot placed on a Redden Skyline positioning block that provides perpendicular beam to film relationship. Note that the cassette is seen in the lower left corner. The opaque line crossing the foot is a metal pointer that is set to the palmar angle of the navicular bone. The pointer aligns the beam, assuring tendon surface relief. To better understand this concept, take a navicular bone or a similarly shaped object in your fingers and sight down the flexor surface from proximal to distal. Rotate the bone around its long axis (i.e. replicate a change in angle of the navicular bone) and see what difference even a slight amount of rotation makes to the area that is thrown into relief. 16A Figure 16. (A) Skyline view taken with the beam at pre-determined angle of 41 degree and the cassette positioned perpendicular to the beam. Using a standard setup, the tendon surface is consistently in relief, and elongation is avoided. 16B (B) Same foot. Skyline tunnel view also taken at 41 degree. Despite proper beam alignment, the tendon surface is superimposed over the body of the bone, and the image is distorted because of elongation. With very few exceptions, only in grade 2-4 (moderate to severe) club feet will the skyline view, taken as advocated by most authors, show the true flexor surface of the navicular bone. A good way of knowing whether your skyline image is truly showing the flexor surface is to take a series of skyline radiographs of an isolated navicular bone, each at a slightly different proximal-to-distal angle. The view that was taken with the true flexor surface in relief then serves as your benchmark when evaluating skyline radiographs of a horse's foot (Fig. 16A, 16B). Due to the complexity of the foot every effort should be made to minimize distortion. Note - When a lesion is found in any part of the foot, on any view, bear in mind that it takes two views, one perpendicular to the other (and both taken with the film perpendicular to the beam), to confirm the presence of the lesion and determine its precise location. Measuring the tendon surface angle of the navicular bone (lateral view) as it relates to the ground surface defines the proper beam angle for this view. Using that angle and a positioning block that allows perpendicular beam film alignment assures tendon surface relief. Digitized Radiography Digitized radiography (i.e. generation of digital radiographic images) is increasingly being used in equine practice. Advantages include the ability to manipulate the image for enhanced detail (including soft tissue detail) and the ease with which images can be stored and transmitted electronically. The initial cost is perhaps the greatest disadvantage. The ability to manipulate the image is also a potential disadvantage, as it may result in artifactual loss of detail and thus diagnostically important information. To get the most out of any radiograph of the foot, whether conventional or digitized, it is important to have detailed knowledge of both gross and radiographic anatomy of the foot and an understanding of the range of normal. And finally, at least one commonly used digital radiography system shrinks the image to 86%. This fact must be borne in mind when taking measurements such as sole depth and H-L zone width from these digitized radiographs. Venography Venography adds information about vascular perfusion to the details regarding bone and soft tissue structure already available from the plain films (Fig. 17). It can be an extremely valuable addition for diagnostic, therapeutic, and prognostic purposes and for monitoring the response to therapy. Venography can readily be performed in the standing horse, using routine x-ray equipment and easily obtainable supplies [2]. Figure 17. The vascular supply to the digit can be demonstrated with a venogram. A thorough working knowledge of the range of normal variations is essential for accurate assessment. Key Points soft tissue pathology is a major cause of foot pain; seek information on the soft tissues in every radiographic examination you perform develop a methodical approach, and use it every time select exposure settings for particular views based on the structure of primary interest develop a series of technique charts that allow for evaluation of different types of tissue (from soft tissue to bone) and different sizes of feet take at least 2 exposures per view; one for soft tissue detail and one for bone detail accurately mark the dorsal hoof wall with radiopaque material for all routine lateral views measure sole depth, dorsal H-L zone width, C-E distance, and palmar angle on routine lateral views for all feet you radiograph to expand your understanding of normal before taking any films, thoroughly clean the foot of all debris, paying particular attention to the frog sulci focus the beam on the area of primary interest make sure the cassette is perpendicular to the beam, on every view, every time aim for a zero subject-film distance on all possible viewsuse a consistent source-image distance make sure equipment and developing system are functioning optimally mark all films clearly and accuratelyinterpret all radiographic findings in light of the history and physical findings 4. Altering Mechanics as a Diagnostic Tool Using a shoe that alters the mechanics of the foot can be a valuable diagnostic tool during a lameness exam. In addition, the horse's response to the shoe provides valuable insight into how the healing environment within the hoof might be enhanced by altering the mechanics of the foot. This novel approach to examining and treating painful feet is very effective in the majority of footsore horses. Using a mechanical shoe to significantly relieve tension in the deep digital flexor tendon and on all related stress points often improves soundness within minutes of application. Arriving at a tentative diagnosis after the physical exam, I usually take two survey radiographs with the shoes on and the horse alert (i.e. unsedated). The routine lateral and DP views described above provide all the information needed to assess hoof mass and balance, and to identify the majority of common soft tissue lesions. Most lame horses do not have bone pathology, so the solution in these cases generally relies on an understanding of how subtle changes in soft tissue parameters affect the overall health and soundness of the foot. The primary problem often involves soft tissue compression and associated vascular compromise which, in many cases, is the underlying cause of the pain and deteriorating hoof mass. I grade the mechanical effect of the shoe or other therapeutic device as follows: one point is given for every 2 degrees increase in palmar angle (with the horse bearing weight on the limb). Thus, a shoe with a mechanical score of 1 raises the palmar angle by 2 degrees; this is a "low-mechanics" shoe. A device with a mechanical score of 5 is one that raises the palmar angle by 10 degrees; the mechanical effect is described as moderate or intermediate. Raising the palmar angle 20 degrees (such as is done for horses with acute laminitis) has a mechanical score of 10; this is a "high-mechanics" device. Depending on the degree of lameness, the tentative diagnosis, and the horse's training schedule, I usually start with a low-mechanics shoe. I move up the scale as needed, guided by the horse's response and how readily the horse can unload the painful area in the particular shoe. I observe the horse at a walk and a trot, on soft and hard footing, on a slope, and on a 30-ft diameter circle. Figures 18A and 18B illustrate the effects of a high-mechanics shoe on palmar angle and functional breakover. 18A Figure 18. (A) Before and after application of a four-point rocker rail. This was apparently caused by a large cystic lesion involving the navicular bone. This shoe was used to define and treat heel pain. See DP view of Figure 12. 18B (B) This shoe was used to treat a Thoroughbred race filly presented with heel pain that was caused by severe caudal rotation (negative palmar angle). Note: Capsular palmar angle A and palmar angle B created with the ground surface. 5. Concluding Remarks Effective examination of the foot hinges on an appreciation of its normal structure and function, encompassing the hoof capsule, soft tissues, vasculature, and bone. Clinical and radiographic examinations are merely discovery exercises, aimed at identifying the area(s) in which structural or functional integrity has been lost. This aim cannot be achieved without an understanding of normal, including an appreciation for the sometimes wide range of normal dictated by the horse's breed, age, environment, and use. It is not enough for us to reach a medical diagnosis; our examinations must have the dual goal of directing us toward a solution to the horse's problem, both immediate relief and a long-range plan for restoring and preserving structural and functional integrity. That goal can be met only when our examinations are aimed at collecting as much specific information as possible, about every component of the digital unit. Although it is important to tailor specific techniques to the goals of the examination, it is equally important to develop and practice a disciplined, methodical approach to both clinical and radiographic examinations. Errors of omission and misinterpretation are minimized when the examiner collects as much information as can be gained from both procedures and considers the significance of the findings in total. Perhaps the single most important addition practitioners can make to their examination procedure is a radiographic protocol which includes views and exposures that provide detailed information about the soft tissues of the foot. Making it part of every radiographic examination will greatly enhance your diagnostic capabilities by allowing you to develop an eye for fine detail and thus subtle abnormalities that would otherwise have been missed. References and Footnotes 1. Redden RF.Radiography of the equine foot-techniques for enhancing the quality of your films.Versailles: Nanric Inc., 2002; 1-24. 2. Redden RF. A technique for performing digital venography in the standing horse.Equine Vet Educ2001;3:172-178. a Intropaste, Barium Sulfate Paste, Lafayette Pharmaceuticals, Inc., Lafayette, IN 47904 or Yorba Linda, CA 92887. b Plexigas, Rohm GmbH & Co., KG, D-64293 Darmstadt, Germany. AAEP PROCEEDINGS / Vol. 49 / 2003 Pages 169-185

Written February 2014 by R.F. (Ric) Redden, DVM The thoroughbred racehorse foot is often plagued with chronic problems, such as thin soles, weak walls, crushed heel tubules, bull-nosed or dished walls, negative PA, quarter cracks and overall lack of mass. While genetics or the rigors of training can predispose a foot to some of these issues, maintaining the foot in such a way to emphasize mass and durability can go a long way towards minimizing or eliminating these commonly encountered foot problems. Like all breeds, thoroughbred racehorses have a wide range of foot stereotypes, all with unique characteristics that make them strikingly different from one another. Matching feet are extremely rare, and often feet on the same horse can have distinctly different profiles. These feet all have different mechanical requirements that need to be met in order to remain healthy and functional enough to withstand the rigors of training. However the traditional mindset that feet should all fall into a narrow range of norm often results in trimming, shoeing and maintenance programs designed to match feet regardless of their individual variability. Striving for the ideal image or balance, as some call it, can often be counterproductive even when all involved have the horse’s best interests at heart. Describing the Healthy Foot The ideal foot we have all been taught to strive for is rarely found outside of a textbook. Therefore we must reconsider the wisdom of constantly struggling to emulate something that does not naturally occur. If a foot naturally has a higher heel and steeper hoof angle than the opposing foot, rather than take it off just because it is there we should first consider why it is different from the opposite low heel foot in the first place. The internal characteristics of a foot, including bone angle, soft tissue parameters, palmar angle, etc., dictate the exterior appearance. Attempting to sculpt the seemingly out of balance exterior to meet our own perceived ideals without thought to what is happening internally often puts undue stress on internal components, which can cause inherent problems that are only compounded by the rigors of training. In order to understand what the foot needs to be healthy, we must first understand what healthy means. It does not necessarily mean normal, as this term should relate to the unique requirements of a specific foot, not feet in general. “Healthy” is dependent on a number of variables, such as foot stereotype, breed, age, moisture content, etc., and there is not a universal standard that applies to all feet. If there was, they would all have to look alike. The belief that all feet should look somewhat the same regardless of where they fall on the large range of variability certainly deserves to be revisited. When evaluating the health of a foot, it is important to note that the time span from the last trim or shoeing greatly influences on how we interpret balance and health. Is a foot shod for 6-8 weeks as healthy as it was when it was first shod? The following external characteristics are indicative of the ideal healthy, shod racehorse foot: Uniform growth rings toe to heel. Rings form approximately 30 days apart and have a wide variety of patterns and characteristics. All feet have growth rings and none are pathognomonic for specific disease syndromes, e.g. prominent growth rings and diverging rings are often mistaken for founder rings. Caution is due as the history, radiographs and clinical findings must support the diagnosis of laminitis. Growth rate variations, other syndromes and injuries also result in prominent and diverging growth rings. Natural front toe angle approximately 52-54° with less than 5° disparity between opposing feet (depending on a 50-51° bone angle, which can vary considerably). Heel angle within 15° of toe angle. Others have advocated heel angle should be within 5° of toe angle, otherwise they are considered underrun. I strongly disagree, as this simply doesn’t occur in the extremely large population of thoroughbreds I have observed and worked with across the horse world. Good growth rate that produces enough hoof length to almost trim off the last set of nail holes. This translates to approximately 10-15mm over a 30-45 day period. Note that growth rate is influenced by weather; in the winter months the hoof is more dormant than it is during warmer months. Trim schedule, exercise, stereotype, environmental conditions, age, disease and injury can all affect growth rate, therefore it is important to be aware of these factors. Healthy feet with slower growth rate can normally have an extended shoeing cycle. Note distance between growth rings, toe to heel and medial to lateral. Face of the hoof is relatively linear, void of dish or bull nose and not influenced by the rasp. Heel height (hairline to ground) is relatively the same between opposing feet. Linear pastern/hoof alignment in a slightly offset plane. Relatively smooth hoof surface void of surface cracks and horn defects. Clinches tight and well set even when shod 4-6 weeks (which indicates low water density and horn rigidity). No overgrown quarters hanging over the shoe during a 30-45 day shoeing cycle. Unshod characteristics: Strong, full thickness wall slightly longer than sole. Strong bars untouched by knife. Good sole mass with cupped or flat sole (as long as it has mass). Wide, strong frog at ground level or slightly deeper within the foot. Heel tubule ground surface contact reasonably close to the widest part of the frog. Medial/lateral frog sulci of equal depth (medial/lateral balance). Medial/lateral equal growth rate (note ring gaps). Radiographic characteristics (on a lateral view taken with Redden low beam orientation): Relatively uniform horn-lamellar (HL) zone (influenced by hoof and bone shape) with variable range of 15-25mm, dependent on age, breed, weight, foot size and lineage. This range is based on examination of several thousand feet, however this range may be much larger among a larger population of thoroughbreds. Lamellar zone relatively parallel.Positive PA of 3-5° regardless of bone angle. Relatively linear palmar rim void of apex erosion, remodeling and the scalloped appearance that is often observed along the central palmar surface. Minimum 15mm sole depth under the apex, preferably 20mm or more, with a slight natural cup at trim or reset time. CE can range from a few millimeters up to 15-20mm on sound feet, relative to stereotype and degree of DDFT tension (high/low syndrome). The largest CE observed by the author on a sound warmblood was 35mm. Digital breakover distance will vary due to foot mass and toe length. Minimum soft tissue parameter disparity between opposing feet. One branch of the palmar rim (medial/lateral wings superimposed). Radiographic characteristics (on a DP view taken with Redden low beam orientation): Medial/lateral palmar rim relatively parallel to the ground surface, and of more importance, digital articular surface uniformity. Even depth sulci. Relatively symmetrical medial/lateral palmar zone bone shape. Relatively equal medial and lateral bone mass. Apex visible slightly distal to wings (positive PA). While these characteristics describe the ideal foot, most feet unfortunately fall outside of these parameters to some degree. However they can remain quite healthy and sound as long as all components (suspension and support) remain in harmony and have natural recall. Be careful not to limit the range of norm when considering balance. What is a healthy, quality prepared foot for one horse may be trouble for the next, and this goes for feet on the same horse. Most all horses have some variation of the high/low syndrome: one foot will have a higher profile than the other, which in the author’s opinion reflects one of four basic grades of the club syndrome. They the same on the inside, therefore they will not be the same on the outside, and forcing them to match will inevitably create unwarranted problems. It is important to keep in mind there is a remarkable range of variability, and often disease and/or injury can result in hoof capsule distortion and soft tissue parameter alteration to some degree. However if the insult to vital growth centers has not damaged the nutrient supply to these areas, evidence of a previous problem may not be demonstrable. The racehorse seldom meets this ideal standard and most all horses in training will fluctuate up and down the scale relative to many factors that are influenced by genetics, conformation, nutrition and farrier and trainer perceptions of what each foot requires. Veterinarians’ perception of the ideal image may be somewhat different from that of the farrier and trainer. Daily maintenance requirements, bedding, exercise, demand for toughness and low moisture content also play a role in the overall level of health of the foot. Management The key to a healthy foot is mass. Trying to establish a well-balanced foot without mass is often counterproductive, as without adequate foot mass to protect the underlying sensitive structures, a foot that is balanced can still be considered borderline at best, unhealthy and vulnerable to injury. Therefore trimming, shoeing and maintenance protocols should be geared towards promoting tough, durable feet with good foot mass (sole, frog, horn and digital cushion) and a slightly positive PA. From day to day care provided by trainers and grooms to routine vet and farrier care, we can determine a foot’s individual needs and design a plan accordingly. When presented with less than optimum mass and balance (medial/lateral to anterior/posterior relationship), our task is to detect the weak area and make a quick assessment of how we can mechanically enhance the natural recovery process, all the while being mindful of internal variations. Doing so at the earliest sign of deteriorating horn matrix offers the largest window of response, allowing us to prevent or at least manage the heel crushing, tubule folding syndrome that haunts an alarming number of racehorses. Farriers worldwide have been unjustly accused of taking the heel off of horses with the long toe/low heel appearance. This is not actually the case however, as other factors contributed to the demise of the heel. The farrier simply removes dirt and frayed, crushed tubules hoping to find solid heel to set the shoe to. This is not a problem with your farrier, but a problem for your farrier. Backing up toes to seemingly correct the long toe/underrun heel foot may appear to make the heel take on a more balanced relationship with the ground. However the toe only appears long because there is no heel. I see a lot of healthy toes and no heel, and therefore do not endorse the long toe/underrun heel theory. Let’s look at the typical yearling foot going into training. Those managed with an ideal foot program and management team will have strong hoof capsule with mass and robust heels whether shod or barefoot. Once confined to a stall 23 hours a day vs turnout, the foot loses demand for toughness. Standing in straw, shavings or paper bedding seems to be the way to bed horses, however they are on their feet the majority of the time and the super soft footing further reduces demand for toughness. When training begins the feet naturally heat up, as do muscles and joints. Then the mud bucket comes out and the feet are packed almost daily to remove heat. The mud dries quickly for the first few days, but then remains moist once the hoof capsule has the same water density as the mud through osmosis. The heat is gone, but unfortunately the strength, rigidity, and recall of all support components have been compromised. I have often encouraged trainers to take photos and baseline lateral and DP foot radiographs of young horses coming into training and observe how quickly the heel begins to crush along with the deteriorating internal balance. Being aware of the dramatic changes early on can greatly help us slow the process and minimize the effects of the heel crush syndrome provided trainers, veterinarians, farriers and caretakers are all on the same page and well aware of the unique characteristics and requirements for each foot under their watchful eye. Once the cycle begins, several major support components fail simultaneously. As the heel angle decreases, so does digital cushion mass. As cushion mass becomes compressed, shock absorbing abilities are greatly reduced, passing excessive load to the heel tubules, which quickly fold inward and forward. As the heel tubules fold the bars do likewise and they lose their strategic shape and location, which is strongest when quite close to the widest part of the frog. The domino effect puts tremendous pressure on the vascular supply controlling growth centers and these vital components, compressing it throughout the horn, cartilage and lamellar attachment. This causes a decrease in toe angle and PA along with sole mass, especially in the heel area. The steeper profile foot may begin to dish and the opposite can develop a bull nose appearance, especially behind. The heel bulbs become remarkably asymmetrical. The medial frog sulci become quite shallow as the heel bulb is pushed more proximal. This is a very misleading external alteration that can be quite confusing to the farrier when they try to balance a foot using the heel bulbs as a reference point. These alterations may not elicit a specific pain response, however as the cycle continues cumulative damage contributes to soreness throughout the heel area. All structures, including the articular surface, are inflamed due to a lack of natural shock absorbing protection to sensitive components. Quarter bruising followed by a quarter crack often results, along with numerous compensating soft tissue and bone injuries that can and far too often do cause catastrophic, crippling or fatal injury. How do we prevent, slow or reverse the cascading series of events? Be alert to the characteristics of a strong, healthy foot, all the while being aware of the large scale of internal variability in high and low profile feet both front and behind, visibly and radiographically. Learn to enhance the strong areas and strengthen weak areas. They will continually change and require astute attention from all concerned. Keep the feet dry and tough. Excess water destroys horn durability and natural recall. Stop and think about what happens to your toenails after soaking for only a few minutes in a hot bath. Throw away the mud bucket. Maintain optimum mass of sole, frog cushion and horn. Remove only what the foot doesn't need and leave nothing that is harmful. Backing up toes to make the heel appear stronger is not a productive procedure; it is not that the toe is too long – the heel is gone. Backing the toe up to make the heel appear stronger simply perpetuates weakness. Maintain full thickness horn wall at ground or shoe surface. Leave maximum frog depth and width. Remove only tags and areas that catch and harbor moist debris. Remove only flaky sole. Leave maximum sole depth. It will not get too thick or too protective. Shoes create painful pressure on shallow soles, while thick, durable soles thrive on it. Therefore shoeing requirements for the shallow foot are quite different from the robust, durable foot. Touch the bars only very lightly if they appear weak and fragile. Otherwise leave them strong and full thickness. Trim to emphasize a positive PA when it is 0° or negative, especially in hind feet. This may call for shoe design that is anything but flat. Hind feet often drift into the negative zone with only few resets as training, speed, hours of inactivity and low or no demand on horn and excessive moisture steadily destroys mass, balance and overall integrity of the foot. This is not a problem with your farrier – it is a problem for your farrier. To prevent this inevitable negative PA development, strive to trim the ground surface to a positive PA every single time. Of course this is dependent on how much you have to start with. Take all you can from the widest point of the foot forward, then take a little more, especially behind. Always be aware of the overall foot mass. The appearance of hind foot sole may lead you to believe you cannot take any more. Work off of lateral x-rays as often as possible to learn what you have to work with and what you have left. Avoid nippers, as the preconceived idea of how much foot needs to come off can compromise our efforts once we discover we need more foot after it is already gone. The rasp allows for more flexibility depending on what we find as we remove excessive horn and the end goal. Tips for preparing the foot for the shoe: Be reasonably certain of the PA and sole depth under the apex. You can only learn this by observing the relationship of external landmarks with radiographic soft tissue parameters. Avoid trimming all feet to look alike with a textbook profile. This can drastically disrupt natural balance instead of enhancing it. Avoid trimming out live sole, bars and frog before removing wall. This practice encourages you to remove more sole than is necessary, which is followed by removing more wall than is necessary. Avoid trimming from toe to heel in a flat plane when heel crushing is present. This invariably lowers PA, creating more of the same with each reset. Consider shoe modification that offers a positive PA and less heel crush benefits. Avoid use of nippers when there is less than 8-10mm of horn wall to remove. You are committed for another 4-6 weeks when the foot is suddenly on the ground and you will have a tendency to follow the wall that protrudes above the freshly trimmed sole. Many traditional trims are designed to take all that is possible instead of leaving all that is protective. Over trimming the sole makes the wall appear excessively long, therefore far more wall is removed than necessary. The wall is nipped off, then lowered even farther by the rasp. This makes the sole look too flat, so it is cupped, once again with the knife. As the frog now appears to be too large it is also taken down with the knife. Now the best part of the foot is on the ground for the dogs. Does this sound familiar? We have all been there. If you want to see stronger, healthier feet then we must have a totally different perception of what we want it to look like when we are finished and what we want to see in 4-6 weeks. Study these tips and try to spend more time observing what is needed instead of removing foot and nailing on the shoes.

Management of Traumatic Injuries to the Hoof Capsule Written and presented November 2005 by R.F. (Ric) Redden, DVM Foal Injuries One of the most common injures to the foot may occur hours to days from birth. Mares occasionally step on their foal's foot while it is recumbent, often causing serious damage to the hoof capsule, soft-tissue and digit. Traumatic wall injuries demand immediate attention and thorough first-aid care. Exam and Debride Many times the wall will be separated from the underlying laminae and sole corium. It is very important to determine the extent of damage and note if any of the germinal centers have been disrupted. The coronary papillae are of great concern, as they are responsible for tubular horn growth. A frequently asked question is, "Should the wall be sutured back on in places where it has been pulled away?" This question has two answers. When the papillae remain inserted in the coronary groove, it is best to leave the wall. The exception is when the traumatized laminae become septic. If the papillae have been displaced from the coronary groove, it is best to remove the corresponding section of wall. Attempting to suture the wall back in place disfigures the papillae, which results in disfigured horn growth, delayed healing and the creation of a bacterial reservoir beneath the detached wall. Radiographs are always indicated with traumatic foot injuries, as fractures are common and often very extensive. When taking radiographs, remember that a foal that is only a few hours or days old requires a very low MAS due to low foot mass and density of the bone. Creating a soft-tissue exposure chart for foals of varying ages is helpful, as over-exposure is often a common problem. General Rules for Caring for Injured Foal FeetRemove all horn that has been detached from the dermis.Remove all bone fragmentsPreserve the coronary papillae and gently direct them downward into the natural direction normal tubules grow.Use firm but very forgiving compresses over all exposed corium to prevent exorbitant granulation.Use a mild iodine solution (less than 2%).Avoid any and all caustic agents that are often used to dry the foot.Protect the fragile vascular bed.Application of a light, short-limb cast that incorporates the foot can also be helpful. Pin casts for severely damaged feet can offer a more favorable healing environment. Iatrogenic Wall Avulsions It is quite common to have foals that walk on their toes at birth. Most respond well to Tetracycline, bandaging, splinting and/or casting depending on the severity of the deformity, size and strength of the foal. Applying a very aggressive toe extension shoe as an aid to stretch the deep digital flexor tendon (DDF) can case catastrophic damage to immature laminae. The result is partial and/or full wall avulsions. If this occurs, debride and bandage the exposed dermis. Protect the digit from being fully loaded by applying a pin cast. Short-limb, bi-valve casts can be easily changed and are useful once the pins are removed. The sole and laminae will cornify within days. New horn wall will grow from the coronary plexus and will totally replace the hoof wall over the course of a few months. Protecting the digit from load is the key to obtaining a functional, healthy hoof capsule. Normally, the new hoof will not be as healthy and tough as the original one, but most cases will have a good prognosis for use as brood animals. Joint Ill Associated Avulsions Joint Ill involving the coffin joint may occur with contracted cases and go undetected in the early stages of splint and cast application. Foals apparently have a high pain threshold and often do not demonstrate an initial pain response to coffin joint sepsis. Therefore, extensive damage can occur. Damage can include PIII fractures and wall avulsions. Septic coffin joints demand emergency treatment, as the cartilage, collateral ligament and tendon attachments can quickly lose their connections and slough, leaving the bone totally detached. The author reports having three cases that required complete removal of PIII. Two of these cases regrew a large majority of their respective coffin bones, and both patients lived to raise several foals. The remaining case presented at 17 days old with multiple fractures of PIII and a fully detached wall. Wall and the fragmented PIII were removed, and the digit was protected with a cast until the hoof capsule regrew around PII. Last contact with the patient was at age two. Fractures Many different types of fractures have been previously described. The scope of this paper is not to describe in detail the etiology and treatment of various fractures, but to help point out the most commonly encountered fractures and useful treatment protocols. Parietal Fractures Parietal groove fractures occur commonly in foals (AAEP 1987). The precise location and size will vary considerably. Normally, the medial wing will be the predominant site; occasionally the lateral wing will also be involved. It is not uncommon to find all four feet with fractures of various sizes. These areas were once thought to be separated ossification centers. However, the work of Dr. Andy Kaneps concluded that separated osseous bodies were in fact fractures. The authors of this paper found that most fractures occur in foals from 4-6 months of age and when the ground is very soft due to excessive rain. Foals trimmed extremely short (which is common in the thoroughbred racing industry) also had a higher incidence of fractures than those with greater foot mass. Using the 4-point trim to enhance foot mass and applying Keratex Hardener daily to the soles during wet weather reduced the incidence of fractures in one farm study from 80% to 4% in two consecutive sessions. Further studies with a large populous of foals are needed to prove the hypothesis that the lack of foot mass and excessive moisture act adversely on the hoof capsule causing parietal fractures. Treatment Only a small percentage of fracture victims experience lameness. Those that do are often 4/5 lame: typical abscess lame. When very close examination with a hoof knife fails to locate a suspicious abscess area, a parietal fracture should be high on your list. Radiographic examination confirms the fracture. A 65 degree DP view taken with a low MAS and a perpendicular film-beam relationship clearly reveals the size and location of the fracture. Tracking the healing patterns of a number of fractures, the author found that the majority healed over the course of 6-8 months. The fractures are space-occupying lesions, as the bone fragment is displaced into the adjacent laminae. The location of the healed, displaced piece of bone is often well defined on the 65 degree DP view when the patient reaches age 2 and 3. This area is often misdiagnosed as pedalostitis. Pedalostitis has a relative homogenous pattern along the quarter margins. The healed fracture has a very distinct line of demarcation that clearly defines the location of the pressure fracture. Some professionals advocate special shoeing as a means to treat this type of fracture. Having observed several hundred cases, the author found that all fractures healed in a 6-8 month period. Special shoes were not used on any of the observed cases. Lameness, when observed, was only evident for a few days and was quickly alleviated with stall rest. The significance of this type of fracture remains unclear. Since it is a space occupying lesion, it may be a precursor for medial quarter bruising and subsequent quarter cracks in speed horses. More studies are indicated. Sagital Fractures Young, maturing horses, yearlings and two-year-olds, are more susceptible to sagital fractures than older horses. A quick, hard blow to one side of the foot apparently causes this type of fracture. Horses that experience this fracture become acutely lame, 4/5 to 5/5, and can remain very lame for several days. Radiographic examination verifies the fracture. The 65 degree DP view with soft and medium penetration reveal the extent of the fracture through the palmar margin, as well as the articulation. The DP view taken with a grid is also a very informative view, as it reveals the degree of sag or step that often occurs at the articular surface. Treatment - Surgical The lag screw technique has been described in the literature, but it has failed to offer consistent, favorable results due to sepsis and other post-surgical complications. Dr. Yukka Houttu of Finland developed a technique that was never reported. It offered a more consistent pattern of healing. Treating several dozen sagital fractures in Finnish racing standardbreds, he found the large majority healed well and returned to racing soundness. His technique involved placing a lag screw in the fragment, followed by placing the sterile wall plug back into the hoof and sealing it with Equilox. Apparently, this prevented invading organisms from entering the surgical site. In emergency cases, elevate the palmar angle to 20 degrees to significantly reduces the pull of the DDF and prevent the distal displacement of the two fragments. Subsequently, this will also reduce the intense pain response. Treatment - Non-Surgical The author has treated several cases using a rim shoe and a 20 degree palmar angle adjustment heel. One two-year-old thoroughbred horse treated with the Redden Modified Ultimate™ and Advanced Cushion Support™ with the breakover modified to produce a self-adjusting 20 degree palmar angle. The devise was glued on with an adhesive for a period of 90 days. The foot was radiographed and trimmed at 45-day intervals. During resets, the horse was never allowed to load the foot without the mechanical aide of the shoe. Following 90 days in the Redden Modified Ultimate™, he was shod with a rockered rail shoe (15 degree - 18 degree PA) for an additional 45 days, followed by 30 days in a flat, steel bar shoe. The fracture healed nicely with very little arthritic change. The horse remains became pasture sound within 3 months. Athletic potential is based on the extent and location of arthritic changes. The prognosis for pasture soundness appears to be quite good based on a limited number of cases studied. Protecting the opposing foot is always a concern. Contra-limb laminitis is often manifested within 3-6 weeks from the initial injury. Using the Modified Ultimate as a prophylactic tool can reduce the incidence of contra-limb laminitis (AAEP 2003). Wing Fractures Fractures that involve the wings of PIII are predominantly found in the medial wing of the right front foot and the lateral wing of the left front foot of racehorses that race counterclockwise. The fracture is often quite painful for a few days, but it seldom causes the degree of pain found with an articular fracture. The majority of these fractures never heal with a complete bony union, even when given 4-5 months of stall rest. However, they apparently become non-sensitive after a few months of rest. A bar shoe that prevents excessive frog compression seems to work well as an aide for treating this type of fracture. Speed horses at their peak are often nerved and remain in training. The efficiency of this protocol needs further study. Articular Wing Fractures Articular fractures through the wings are quite painful and can remain very painful for several days and/or weeks. The 65 degree DP, the 65 degree 45 degree oblique, and the DP with the grid are radiographic views that clearly reveal the limits of the fracture, as well as the displacement, that is often described as a "step fracture." Observing the characteristics of the step fracture reveals that a large segment of PIII is displaced distally when the foot is loaded. It is the hypothesis of the author that the DDF pulls the larger segment distal when the foot is loaded. The other segment is significantly smaller and has less DDF attachment; therefore it is not influenced by the pull of the tendon. The pain response appears to be due to the grating effect of the larger segment on the smaller one. Applying a shoe that offers a minimum 20 degree palmar angle significantly reduces the DDF pull, therefore significantly reducing movement and displacement, and subsequently the pain. Using this shoeing protocol for more chronic fractures may reduce the pain response, but it is unlikely that it will correct the displacement. Most of these fractures appear to heal radiographically in 4-6 months, but after observing several dozen post mortem cases on older horses, the author found none of them to have a solid bony union. Several of these horses apparently sustained fractures as racehorses years earlier and prior to their death as aged breeding stallions. All had a cartilaginous zone separating the fragments, as well as a large overlapping callous on the dorsal surface. This gave a radiographic perception that the fracture had healed. Most horses that experience these fractures become athletically sound with 6-8 months of rest; 4 months stall bound and 4 months of limited exercise. Unfortunately, most sport horses will step down in class apparently due to varying degrees of arthritic changes. Nerving may be performed as a means of improving training soundness, however, sequestrum fractures have been found to be associated with articular fractures in horses that were nerved and kept in training. Septic sequestrum deep within the foot can become life threatening. Palmar Margin Fractures Thin-soled horses turned out on frozen ground are subjected to excessive trauma to the sparsely protected coffin bone. Racehorses and other sport horses let down for the winter often have their shoes pulled for winter turnout. Their feet are vulnerable to sever bruising and rim fractures simply due to the lack of healthy sole depth. Bi-lateral bruising and or fractures along the palmar margin appear clinically much like a laminitic case; and subsequently, they are misdiagnosed as such. Clinical Signs of Acute Lameness Unilateral versus Bilateral Many days following the initial trauma, the sole often appears soft and necrotic, and the sole corium is exposed. At first glance, this may appear as penetration of PIII, especially when the sole is exceptionally thin. It is common to find racehorses with a mere 6mm of sole that remain in training. This is far from the healthy 15mm required for adequate sole depth. Very low MAS radiographs clearly reveal the fracture along the palmar margin. The 65 degree DP and 45 degree 65 degree DP Oblique views best reveal the extent of the fracture. Film taken for bone detail will invariably burn through the thin fractures and obscure the evidence of their existence. Treatment Application of a hospital plate shoe prior to debridement facilitates the treatment protocol. The majority of these cases can be debrided using good sedation, as the necrotic area is normally desensitized. The small slivers of bone can often be removed without using a local block. Once the area is debrided, apply firm pressure by packing the defect and sole with Betadine impregnated gauze to prevent excessive granulation. The treatment plate will adequately protect the sole and often provide adequate positive pressure to control bleeding in the site. Complications are rare, and most cases will heal within 30 days. The hospital plate should be used until the sole has fully cornified. Using a pad under the shoe for another 30 days will help prevent unwarranted bruising. Traumatic Wall Injuries Bulb, heel and wall lacerations can be very minor or quite excessive. Metal objects, glass, fence and wire are the most common causes of lacerations. Other horses can cause serious damage and injuries, too. It is important to determine the extent of the injury by performing a thorough clinical and radiographic exam. For wall ablation injuries, the author prefers to apply a custom fit hospital plate shoe prior to debridement. Make a cardboard template of the area that needs to be protected. Mark a piece of 1/4" aluminum and cut the sole plate and extension from one solid piece. Forge them to fit over the defect. Allow a 1/8"-1/4" space between the hoof and convex cover to facilitate proper fit. This will foster pressure on the debrided area. The goal is to provide positive pressure on the laminae and granulating wound, while preventing the soft tissue from protruding past the normal anatomical limits. The tissue will cornify regardless, but the most optimum results are obtained when cornification takes place at the base of the adjoining healthy wall. Puncture Wounds - Indirect Sepsis that invades the soft tissue is a very common problem with horses that have a hoof capsule that is not healthy. Disruptions in the normal, healthy sole/wall junction allow moisture and bacteria to enter the sensitive, and highly vascular, corium and/or laminae. Better know as abscesses, they often cause an acute and very painful response. An abscess can be far more painful than fractures and should always be high on the list when examining an acutely lame horse. Cleaning the foot up with a rasp will most always reveal linear, dark splits in the inner horn and sole/wall junction. Many times there will be several small, dark lines. Discreet use of a hoof tester will help locate the area that is most sensitive. Opening the track through the wall offers tremendous advantages to going through the sole. The goal is to establish drainage without exposing any sole corium. Sole corium drainage can be established using a small curette (2mm), a horseshoe nail with a small hook on the end, or a custom screwdriver with a darning needle hook tip. Using the “small hole approach” prevents corium prolapse that can be a problem for weeks. It is easier to reopen the tract, if necessary, than it is to deal with a large, sensitive polyp of sole corium. Bandage the areas with Betadine to protect it from getting debris packed into the tract. Most cases will heal is a couple days. Those that fail to heal properly will remain painful for 5-7 days and should be radiographed for potential bone involvement. Puncture Wounds - Deep Puncture wounds involving the DDF and/or navicular bursa and bone are life threatening until proven otherwise. They should be treated as an emergency case. Evaluate the structures involved using a sterile probe, in conjunction with radiographic information. There are several methods for treating deep wounds; each has merits and drawbacks. The general rules of thumb that have helped me with many serious cases are: Establish drainage.Remove any and all necrotic tissue.Totally unload the DDF using an adequate hospital plate/raised heel shoe that creates a 35 degree - 40 degree PA.Treat with a broad-spectrum antibiotic until culture sensitivity has returned.Use adequate protective mechanics to prevent contra-limb laminitis in the opposing foot.Apply firm pressure to the site to prevent excessive granulation. Extensive Heel Bulb Lacerations Wire and metal induced lacerations are often very extensive. The majority will involve the heel and lateral cartilage. In this case, thorough debridement is indicated. Deep lacerations should not be sutured due to the pooling effect. Many of these cases will heal well in a foot cast that limits motion. Most heel bulb lacerations also disrupt the coronary groove, which causes permanent scaring and subsequently chronic quarter cracks. Athletic horses with permanent scars often require stability patches on this area to remain sound for training. Catastrophic Lacerations Lacerations involving the majority of the vascular supply of the digit are fatal. Amputation of the digit is a viable option provided it is performed in a timely fashion, the goals and dedication of the client are clearly defined, and adequate equipment and experience compliment the procedure. The prognosis for a reasonable quality of life is good for hind feet, while a higher-degree of risk is associated with front feet. Rim casts are a tremendous adjunct to therapy for all amputation cases. Frog implants in the granulating stump tissue have also been a tremendous aide in creating a tough stump pad. Prosthetics are used until the stump has matured. More permanent, fitted prosthetics are indicated for long-term cases.

2002 - 15th Annual Bluegrass Laminitis Symposium Notes Interpreting Soft Tissue Parameters and Lesions - The Influence of Trimming and Shoeing the Normal and Pathological Foot Written and presented January 2002 by R.F. (Ric) Redden, DVM Developing a detailed, methodical radiographic protocol is the first step in learning the healthy range of soft-tissue parameters of the equine foot, in addition to the commonly found soft-tissue image variations. Radiography should be considered a discovery exercise, as we are seeking information that will confirm, aid in the diagnosis of pathology or reveal parameters or lesions that may suggest a diagnosis. Farriers need DP and true lateral views to fully assess anterior-posterior balance, medial-lateral balance, sole depth and the palmar angle. Simple imbalance can lead to soreness and lameness that can be quickly alleviated with therapeutic trimming and shoeing. This information allows farriers to assist the attending veterinarian with a large variety of foot problems. Knowing your equipment and how to get the most from it allows the radiologist to make finite adjustments that meet the demands of the exam. The Lateral View In order to take a true lateral radiograph, the primary beam should be centered 3/4 to 1 inch over the positioning block or at the level of palmar surface of PIII. The true lateral will offer information on sole depth, HL zone, CE, palmar angle and digital breakover. Sole depth Sole depth is measured from the apex of PIII to the ground surface. Breed and other factors influence the depth of the sole. Centering the beam close to the palmar surface offers accurate measurement of the distance between the palmar surface of the shoe or ground surface. Your positioning block also needs an opaque marker (wire embedded in the face of the block works well). This marker clearly reveals the ground surface of unshod feet. The shoe becomes the marker for all shod horses. When taking a true lateral radiograph, notice that the film will have the branches of the shoe superimposed; therefore, you will only see one branch of the shoe. The barefoot horse will seldom have air density between the sole and the opaque marker, as the sole is a natural load bearing surface. Often though the shod horse will have air dense space between the sole and the foot surface of the shoe. This space is present for several reasons, each of which is considered vital to full assessment. Strong feet with adequate mass and ideal conformation have a natural cup that often produces a large air space between sole and shoe. Trimming the feet also greatly influences the sole depth and cup of sole. When comparing changes in progressive film, it is necessary that the film be comparative. Measuring the sole depth on every lateral film will help you develop an eye for the range of normal or at least what you normally find on the feet you examine. There is a difference. Like all other parameters, if you only measure the pathological cases the range of normal will escape you, diminishing your ability to distinguish subtle pathological lesions. Mature five inch feet on most light breed horses will have a sole depth of 15-20 mm. Fifteen millimeters is the minimum depth. Venogram studies on many sound feet with good conformation indicate that the sole corium normally occupies approximately 10-12 mm of the solar depth. The concave surface of the sole and/or coffin bone is not visible on the lateral projection; therefore we are seeing the depth of sole directly beneath the perimeter of PIII. Less than 15 mm of sole depth is considered inside the comfort zone, as there is not adequate room for the normal circulatory solar plexus. Race horses and event horses that often have 10 mm or less are generally foot sore horses with collapsed heels and extremely thin walls. Regardless of the concomitant pathology, their feet are severely compromised on a good day. Sever lack of foot mass is the primary diagnosis. Excessive wear can be a contributing factor for thin-soled, barefoot horses, while unshod horses that paw continuously when tied can quickly remove several millimeters of sole and toe. This wear pattern will be obvious to the trained eye. I use my film to confirm a diagnosis, while including evidence found through a thorough physical exam relative to the history. White line disease and other common problems certainly have pathognomonic lesions, but a good history and even better exam will often become quite valuable. The acute stage of laminitis can be more difficult to diagnosis and assess due to similar pain-producing syndromes; therefore, astute attention is required when examining the foot, the film and the history. Baseline film made prior to your examination can be invaluable especially if positioning and film detail are relatively comparative. Pre-purchase film taken months before can be invaluable, but keep in mind that the purpose of the pre-purchase exam may have been quite different than yours. Beam positioning and detail may vary considerably forcing you to read between the lines. Comparative films are just that, they have identical positioning and detail. I like to first identify beam location and make a written note of the dissimilarities concerning detail and content then pass my opinion concerning the similarities. Having a very strict, personal protocol offers me significant advantages for all comparative films. Horn-Lamellar Zone (HL) Horn-Lamellar zone is one of the most valuable parameters for assessing lamellar and horn health. This zone is greatly influenced by beam positioning. To alleviate distortion, a consistent, perpendicular beam-film relationship must exist and be centered at the area of greatest interest. I like my primary beam to strike the foot at the approximate level of the palmar surface. This offers accurate measure of the depth of sole, thickness of the lower HL zone, and palmar angle. The upper HL zone is slightly distorted, but with consistent positioning this distortion remains constant. Most light breed horses will have an HL zone measuring 15 mm. When taking this measurement, I use two points of reference: the area just beneath the extensor process and the apex of the coffin bone, measured perpendicular to the wall marker (opaque paste). Exceptions to the normal 15mm HL zone include Standardbreds that generally measure 18-20 mm. Aged, heavy Thoroughbred brood stock and stallions will often measure 20 mm or more. Warmbloods and others with 5 inch wide feet will also range from 20- 22 mm. Most often the front and hind feet will be very similar, within 1-2 mm. Weanlings and yearlings will vary greatly depending on their stage of development. Normally the upper measurement will be greater than the lower by 1-2 mm. Adult horses that have had their toe backed up hard will have a smaller zone at the apex. Radiographically, there is a striking difference on a backed up toe. The opaque zone seen on the radiograph delineates the junction of sensitive and non-sensitive laminae. It also clearly reveals lamellar thickness within the lamellar space, in addition to horn depth. This normal soft tissue structure is an invaluable aid when distinguishing rotational changes that have occurred within the horn wall (e.g. white line disease and occasional club foot) verses capsular rotation that occurs due to laminitis. Law suites often hinge on which side of the zone is beyond the range of normal. Subsequent films taken after your baseline views may reveal subtle but significant swelling of this zone. With laminitis these changes are very significant and often can be visualized long before other more obvious signs of rotation and/or distal displacement have occurred. Clinical cases that have 10 mm of acute lamellar swelling as a rule have a grave prognosis. Success with these cases is dependent on swift reperfusion of the digit. Chronic thickening of the lamellar zone must not be confused with acute swelling seen in acute cases. These are two totally different problems often can only be distinguished with a venogram. Palmar Angle This angle is measured by drawing lines along the palmar surface of the wings of PIII and the ground surface. The angle where these two lines intersect is the palmar angle. I measure at the wings because they better represent the body of the bone, and represent the area of the digit designed to carry load and absorb tremendous energy. The palmar surface at the apex is often in a more proximal plane. In addition, the sharp, fragile border of the apex is often distorted due to pathological conditions that cause excessive loading and trauma. Bending or lysing can be found with club feet, laminitis, white line disease, flat, shallow feet and a variety of flexor deformities. Measuring the angles can be arbitrary and non-specific as there is seldom a straight line to follow. I am concerned with large increments of angle change; 5-10 degrees or15-20 degrees, as smaller more detailed changes are difficult to measure and do not add to the big picture. As a farrier, I use this angle to help design all therapeutic shoes. This angle can range from a negative 10 degrees (severe caudal rotation), which is frequently found in rear feet with very steep coronary band angles, to 45 degrees in severely rotated, chronic laminitic cases. Ponies and other breeds with very upright hoof capsules often have relatively thick soles with deep cups. These feet may be 15-20 degrees in their normal state. Coupling the palmar angle with sole depth and HL zones, we can find a direct correlation to the events that precede many pathological conditions. Pathological conditions that involve the apex, anterior lamellar zone and horn wall can be treated successfully by shifting load away from diseased areas to the healthier heel zone. I often use the palmar angle to facilitate this mechanical advantage. Utilizing the simple mechanical shift of load enhances the healing environment and diminishes the painful response. This offers the podiatry team a meaningful, reliable means of treating a variety of foot ailments. The normal palmar angle is certainly not written in stone, as it varies considerably among breeds as well as within breeds due to unique characteristics of foot conformation, environment, training demands, etc. As a rule, light breed horses with acceptable, sound hoof conformation will have a natural 3-5 degree palmar angle in the front and slightly higher in the hind feet. The coffin bone angle is normally 50-51 degrees in most feet . The exception are club feet and extremely low angle hoof capsules. These feet will have a hoof angle somewhere between 53-56 degrees. This is not a standard, just a reflection of a collection of commonly found normal feet. Mustangs that I have radiographed in northern Nevada were quite flat and void of a palmar angle. A stark difference can be found with the internal structures of these feet verses the domestic foot. Domestic feet with a flat (zero) palmar surface have a crushed digital cushion, normally thin soles, thin walls and an assortment of heel related soreness. I am often asked, "What is the ideal palmar angle?" I really cannot say without a reference to breed, sport and conformation of each individual case. Digital Breakover To measure digital breakover, drop a vertical line from the apex of PIII to the ground surface. Measure forward to where the shoe or bare foot no longer touches the ground. This distance is the digital breakover. This point is where the hoof and shoe pivot forward as the heel leaves the ground. Prior to the heel leaving the ground, tremendous forces are executed around the apex of PIII. The coffin bone is actually suspended within a very flexible soft tissue, blood filled cushion. This very flexible, but yet durable, strong attachment is compressed in areas and stretched in others before the heel begins to lift. Therefore, I prefer to reference the point of digital breakover at a level compatible to internal pivot of the digit instead of a line carried along the face of PIII to the ground surface. This point of reference is dependent on sole depth and/or shoe thickness which play a role in the forces applied to the true point of digital pivot or breakover. The length of digital breakover becomes a valuable tool for the podiatrist team because manipulating this distance drastically changes the tension or resistance of the deep flexor tendon and other supporting ligaments and tendons. The pure lateral soft tissue detail film with wall and ground marker is a most valuable blueprint for the podiatrist team. Measuring the HL zone, sole depth, palmar angle and digital breakover, coupled with a working knowledge of soft tissue lesions associated with the four parameters, lays the ground work for the discovery and planning phases that should precede any and all therapeutic protocols. Without these parameters, I would have to resort to external manipulation as the only means to shift load or relieve other areas of compression and tension. Having good quality film available for the farrier prior to and following shoeing can be a tremendous asset for treating all career and life threatening foot problems. I sincerely feel it is the responsibility of all veterinarians to seek out the podiatry focused farriers and help them develop skills in reading basic soft tissue parameters and the silhouette images that directly relate to their respective job. Lucent Sub Wall & Sub Solar Lesions The lucent zone found along the junction of the opaque zone is a pathognomonic radiographic sign of laminitis. However, care must be given to the detailed characteristics of this lesion. The proximal and distal extents of the lesion have a small radius and the entire lucent zone has smooth, straight sides. When rotational changes have occurred the bottom zone is wider than the top and stops abruptly at the inner face of the sole. Even with cases of severe rotation and penetration of PIII, anatomically this is the distal limit of this lesion. The lucency found in the same general area that is pathognomonic for white line disease is strikingly different, as are the history and clinical findings. White line disease initially involves the white zone or non-pigmented zone of the horn wall. This term is very deceptive as the disease involves the non-pigmented horn between the terminal laminae, which is actually yellow to dark brown in color; not white. Regardless, the invading organisms apparently travel from the ground surface and invade a pre-existing weakened area of soft, white horn. We only have speculation at this time as to how the area is weakened, but evidence supports the hypothesis. Nevertheless the lucent zone is characteristics of horn invasion and differs greatly from that of laminitis. The entire margin of this air space is irregular with peaks and points that often appear to run inside the bone. They actually extend around the circumference of the hoof and are superimposed over the bone. The distal margin continues to the inner sole then emerges at the ground surface. Looking closely at the inner sole zone you will often find a molted appearance, which is normally dirt, small rocks, sand and other debris. This very significant finding may be missed or attributed to dirt on the outside of the foot. Lucent zones that represent gas forming, bacterial invasion of the soft tissue structures will have very distinct characteristics as well. They normally are small lesions, circular in formation, and can occur as a linear, small line or separate air dense areas along the sensitive junction. Extensive invasion can be seen to involve the bone as well. Old draining tracks can be seen within the horn wall, most having distinct marks visually seen on the surface of the hoof. Full thickness toe cracks often have a heavy scar that creates an invaginated area along the face of the hoof. A lateral radiograph will often reveal a lucent zone that appears to involve the wall. Lucent configurations can be found within the sensitive sole zone representing active gas forming bacterial sepsis, chronic abscess with or without serosanguineous pooling. With laminitis the very path of the apex can be tracked as it descends due to rotational changes and/or sinking. Lucent zones can be found in the heel and frog zones as well. Suppurative corns in the angle can be demonstrated by the pathognomonic lucent lesions more clearly seen on the skyline view radiographs. Severe bruising, with or without sepsis, can be seen as lucent zones along the sulcus of the frog and/or bar and lamellar zone of the bars. The skyline view confirms the lucent line seen on the lateral. Opaque Lesions Calcification of previously injured areas can be found within ligaments supporting the articular structure of the coffin joint and navicular bone. Areas of calcified hemorrhage can be found within the body of the deep flexor tendon as it courses down the pastern and over the navicular bone. Bone proliferation along the anterior face of PIII often involves the laminae as well as the bone. Laminitis cases that penetrate often have a tremendous soft tissue and bone proliferative response that can become permanently disfigured and often remain septic for the duration of the individuals' life. Calcified lateral cartilage is best demonstrated with soft-tissue detail and non-distorted radiographs. The foot placed in the tunnel and x-rayed with an oblique beam projection grossly magnifies and distorts the side bone formation. This often provides misleading data. The lateral and DP views taken with the beam centered at the coronary band provide the view of least distortion. Fracture lines are often associated with soft tissue pathology as well. The marginal fractures of the palmar surface of PIII often are found displaced and embedded within the sole corium and laminae. Wing fractures that are articular in nature often have a step formation at the articular surface. The step can also be seen on the DP view as the large section of bone is pulled distally via the deep flexor. My treatment addresses the tension on the deep flexor, which aids opposition of the fragments. This approach reduces pain and enhances healing. Fracture lines occur in at least eight planes. How do shoeing and trimming influence soft tissue zones and anatomical landmarks? Rasping the front wall in an effort to improve breakover is a common practice among farriers worldwide. The wall can only be backed up reducing breakover 3/8 to 1/2 inch. The significance of this technique is questionable. The opaque zone (sensitive/non-sensitive laminae) clearly reveals the mechanical loss of horn. Trimming has been mentioned as a means to reduce the radiographic distance between the palmar surface and the ground or shoe surface. Trimming also directly affects the palmar angle. Changing the palmar angle directly influences the alignment of the digits, in turn significantly altering the breakover of the shod or unshod foot. The farrier has a tremendous influence on the sheer mechanics of the foot. Knowing where the hotspots are and how simple manipulation can work to relieve these areas is the basis of all pathological shoeing. The foot, as a whole, is a unique and very complex organ. Altering one area directly affects others. The same can be said for pathology. Therefore, we must always be cognizant of the ill effects, as well as the positive effects, of our efforts.

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SHOEING THE LAMINITIC HORSE R. F. Redden, D.V.M. P.O. Box 507 Versailles, Kentucky 40383 Reprinted with permission from the American Association of Equine Practitioners. Original printed in the 1997 AAEP convention proceedings. INTRODUCTION: Laminitis is a complex disease syndrome often seen subsequent to a variety of primary diseases. The prognosis ranges from good to grave and is dependent on the degree of damage to the vital supporting structures and mechanical stability of forces perpetuating displacement of PIII. This syndrome demands the expertise of professional farriers, as well as veterinarians as therapeutic shoeing plays a major role in the successful treatment of the majority of laminitic horses. Treatment length can vary from a few weeks to years, requiring commitment and dedication for seemingly endless maintenance regimes. Establishing an effective protocol to treat laminitis will improve the treatment regime and help farriers and veterinarians gain good experience. Success rates vary from horse to horse and are greatly influenced by the ability of veterinarians and farriers to assess the damage, read the particular needs and treat the syndrome with a progressive attitude, built on knowledge of the subject and professional camaraderie. INITIAL EXAMINATION: Obtain a good history and carry out a thorough physical examination to include radiographs on the first visit. Laminitis often follows other primary disease maladies, such as colitis, pneumonia, pleuritis, retained placenta, dystocia, potomac fever, blister beetle ingestion, protracted diarrhea, salmonella, selenium toxicity, fescue poisoning, injudicious use of corticosteroids, stress, contra limb acute lameness and others. Be alert to the hoof characteristics that vary from normal, both grossly, as well as radiographically. Being focused on details will help rule out other acute foot problems that closely mimic the signs of laminitis. TAKING RADIOGRAPHS: A methodical, disciplined technique assures consistent, good quality, pure lateral projection. Soft detail images reveal anterior-posterior balance and the relationship of PIII to horn and horn to load. These parameters must be clearly demonstrable as they become an essential guideline for pathological shoeing. Most professional farriers have become quite proficient reading good quality, soft tissue detail film, as it relates to their task of re-establishing a meaningful equilibrium. Films taken before and after each shoeing session tremendously increase the knowledge bank and efficiency of farrier and veterinarian and consequently improves the prognosis. Practice tips that have improved my technique: Pure lateral, primary beam strikes the foot in a horizontal plane, just above the ground surface. Zero film, subject distance. Opaque marker, detailing the face of the horn wall, as well as ground surface. Positioning block, 3 x 5 x 7, with a wire running through the long axis is compatible with most all x-ray machines. RADIOGRAPHIC INTERPRETATION: The distance from the face of PIII to the outer horn wall is referred to as horn-lamellar space. Become familiar with normal parameters. Most light breeds will measure 15 to 17 mm., heavy, older broodmares, stallions and most Standardbreds will measure 20 to 22 mm. Base line views become most valuable as they establish a starting point. The depth of sole and cup directly beneath the apex of PIII is quite easy to monitor with pure lateral films. Extensor process relationship to coronary band varies from horse to horse and foot to foot. Rely on the base line film to assess starting location. CLASSIFY THE DAMAGE: Rotation is significant with acute cases but is very misleading with chronic cases due to abnormal horn growth. Classify the damage before establishing protocol. A scale of 1 to 1000 offers a realistic classification system for all laminitic cases. Classify each horse at onset based on history, physical and radiographic examination. Design therapy to reverse forces at play and meet the needs of the patient. This system enables me to treat not only each case but each foot as a separate entity and to better explain the seriousness of the syndrome to my clients. TREATMENT: Acute laminitis should be considered an emergency because the window of maximum response closes rapidly. Sound mechanical therapy applied in a timely fashion can be very effective against secondary compressive damage seen subsequent to displacement of PIII. Preventing and or minimizing displacement in the face of this syndrome can alter the course of the disease. THERAPEUTIC: Treat the whole animal, address primary problems when known. Use anti-inflammatories with discretion. Phenybutazone remains the drug of choice. Many others have good to excellent anti-inflammatory properties and can be useful. Nitroglycerin creams and patches have been advocated recently and may have potential. Caution; use with discretion and be judicious. Teach proper use and handling of these products as they have precautions and contra indications. Apply emergency aid designed to significantly reduce deep flexor pull, Modified Ultimates, Advance Equinea. The clinical response will aid in assessing soft tissue damage. Before applying any therapeutic device become familiar with the specific conformation characteristics of each foot. Learn to read positioning of PIII within the capsule with the aid of radiographs as well as without. Three basic principles are very effective against deep flexor pull as it opposes diseased laminae: Raising the heel 10 to 18 degrees significantly reduces pull on the tendon. Placing breakover directly beneath the apex of PIII, (phalangeal point of rotation), eliminates opposing lever arm and significantly reduces lamellar stress and sub solar compressive forces. Utilizing sole, frog, bars and sulci as uniformly loaded support zones. Success with mechanics lies in applying a device that meets the specific needs of each foot. Years of experience are required of veterinarians and farriers to properly read feet. A common error is to lump all feet and all cases in a basic category. This philosophy fails to produce favorable results the majority of the time. Very basic guidelines to help load the heel and unload the apex and laminae: When rotation is present the hoof capsule must be trimmed in a fashion that re-aligns PIII with the natural load surface, otherwise the apex of PIII continues to compress sole corium, further compromising circulation. Trim the heel parallel to the freshly trimmed frog starting at a point just behind the apex of the frog. Rasp the heel down at the base until good, sound horn tubules are evident at the widest point of the frog. Use discretion as over trimming can produce harmful results. The horn capsule forward of the apex of the frog will not make contact with the shoe, therefore we are shoeing to the heel, not the toe. All nails must go behind the widest point of the hoof in order to secure the shoe to the heel. Re-alignment normally increases deep flexor pull depending on severity of displacement, hoof angle, heel angle and breakover placement. Raising the heel once properly derotated increases load to the heel area and reduces tendon pull influencing sole corium and lamellar perfusion. Leave all the sole and foot mass possible as it is natural protection and desperately needed. Design the shoe so breakover is 3/4 of an inch forward of the true apex of the frog. Note; many times the frog will lay on top of the sole giving false impression of the true location. Trim the toe at a 45 degree angle with the ground surface to avoid breakover contact. Stay well forward of the natural sole. Resilient custom fit arch support offers a broad spectrum, evenly distributed support surface that reduces load on the diseased laminae, Advance Cushion Supportb . Strict stall rest throughout the recovery period reduces unwarranted stress on the healing laminae. Note; recovery period is dependent on damage. Cases with significant rotation and/or sinking must re-establish lamellar integrity or relatively normal horn growth pattern and a dense sole to reach optimum recovery, six months to one year is a normal recovery period. UNFAVORABLE TREATMENT RESPONSE: When faced with an unfavorable response take lateral radiographs with the shoes on. Routinely taking films following every therapeutic shoeing and focusing on small details improves the end result. Check for proper derotation, mass of heel, sole impingement, progressive displacement (rotation, sinking and lamellar thickening). Keeping in mind the normal, evaluate the coronary band and look for sensitivity, discoloration, moisture and abscessation. Take dorsal-ventral views, look for pathological solar fractures. A venogram of the digit is a helpful aid for determining circulatory damage1 & 2. Classic sinkers have a stark loss of contrast throughout the laminae, sub solar area and within the semilunar canal. Subsequent venograms can aid in assessing progress with cases showing marginal loss of contrast on the initial examination. When faced with a poor or slow response following proper derotation and shoeing, consider deep flexor tenotomy as an adjunct to therapy. Deep flexor tenotomy should be considered a viable means of treating complicated laminitis. Proper derotation, shoeing and timely surgery can offer penetrated laminitic cases full recovery. THERAPEUTIC SHOEING: Therapeutic shoeing is indicated for laminitic cases that develop five degrees of rotation or greater and all with sinking of any degree. Progress in the field of pathological shoeing has accelerated over the past ten years due to combined efforts of farriers, veterinarians and research. Currently I prefer to fabricate a four point rail shoe, similar to the shoe by Gene Ovnicek3 . I have modified the concept to increase toe protection and applied a sole to ground resilient arch support. There are many ways to make this shoe. Farriers need to know the basic principles of construction and application. Breakover is at the widest point of the foot, just in front of the apex of the frog. Rails reduce tendon pull and enhance medial-lateral breakover. Arch support offers broad spectrum support to the sole, frog and bars. Properly placing the shoe on a derotated laminitic foot with adequate mass of heel can offer a more consistent measure of successfully treating laminitis. The shoe has offered a favorable response for sinkers and cases with penetration. This shoe and technique enhances the effects of deep flexor tenotomies. CONCLUSION: Ninety-four horses were shod with four point rail shoes with Advance Cushion Support. 75 had greater than ten degrees rotation. 38 had greater than 1 centimeter of sinking. 40 penetrated the sole. 38 treated with deep flexor tenotomy. RESULTS: Twenty-four returned to previous status.Of these twenty-four there were seven broodmares, one stallion, one Arab show horse, one Quarter Horse, one Paso Fino, five Walking Horses, one Saddlebred, one Morgan, one Show Hunter, two riding horses, three were penetrated; one Paso Fino, one Walking Horse and one Thoroughbred broodmare. Thirty-one returned to pasture soundness. Sixteen were penetrated, three Saddlebreds, one Arab, four Thoroughbreds, two Quarter Horses, one Standardbred, four Walking Horses and one Morgan. Nineteen were euthanized. Nine sinkers with penetration, one penetration and nine chronic cases with extensive osteomyelitis. Thirteen could not be located for follow-up. REFERENCES: 1. R. F. Redden, D.V.M. The Use of Venograms As A Diagnostic Tool. Bluegrass Laminitis Symposium, 1993. International Equine Podiatry Center, P.O. Box 507, Versailles, Kentucky 40383. 2. Chris Pollitt, DVM. Personal communication. University of Queensland, Saint Lucia, Queensland 4072, Australia. 3. Gene Ovnicek. 525 Half Moon Road, Columbia Falls, Montana 59912. FOOTNOTES: a. Modified Ultimates. Advance Equine, P.O. Box 54, Versailles, Kentucky 40383 b. Advance Cushion Support. Advance Equine, P.O. Box 54, Versailles, Kentucky 40383

Written March 2014 by R.F. (Ric) Redden, DVM I devised a new concept a few years ago that sorts out foals with weak flexors. This foal with weak flexors (left) was treated with the bungee concept described below. The photo on the right was taken one week after application of the bungee and therapeutic shoe. Most foals will only be weak in one limb. However, if the case is bilateral, a shoe on each foot is indicated. Add a piece of 3mm (1/8") aluminum to the bottom of the Dalric heel extension shoe. Use a clip up front to take load off the rivets and add a leather or nylon loop in the extended area. Back the heel up to the widest part of the frog before gluing the Dalric shoe on with Equilox or Vettec SuperFast. Bandage the leg using 50" of good, firm cotton wrap.  Select a bungee that will be compatible with the size of the foal.  Remove the hooks from the end of the bungee and run it through the loop of the shoe and up the back of the leg.  Pick the hind leg up by the hock when hind feet are involved. This will naturally flex the joint.  Then tape the end of the bungee to the upper portion of the bandage using 4" Elastikon. You can also use a single bungee as shown above, or a piece of rubber inner tube as your elastic support. Flexing the fetlock and coffin joint while taping the bungee in place offers just enough tension when you set them down. This creates a natural, elastic tendon response that offers good healing time for the exceptionally long flexor muscle. Where casts seem to weaken the muscle, the bungee appears to offer just enough support to allow it to strengthen. Normally most foals only wear the bungees for a few days with mild to moderate cases and the shoes for a couple of weeks. Those with long pasterns and weak flexors may require more time. Even very difficult cases have responded very well using this concept. Give it a good effort, and if you have any questions get back to me as I will be eager to help you and see your results.

This particular soft-tissue parameter evaluates the position of PIII in relation to the coronary band. You can only get a true and accurate measurement if the barium paste wall maker extends up the hoof wall to the hair line of the coronary band. Without the marker, this area is not visable radiographically. This soft-tissue zone should be monitored closely in acute laminitic cases. As the CE increases, notice that the sole depth decreases. The sole depth also decreases when the foot is trimmed. You must learn to tell the difference. To measure the CE: Step 1 Locate the proximal (top) extent of the coronary band as marked by the white barium paste. Draw a line from PII past the outer edge of the hoof wall. This line should be parallel to the ground surface. Step 2 Locate the proximal (top) extent of the extensor process. Draw a line from this location past the outer edge of the hoof wall. This line also needs to be parallel to the ground surface. Step 3 Measure in millimeters the vertical distance between these two lines. In this case, the CE measures 15mm.

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Indepth Equine Podiatry Symposium Notes Written and presented January 2010 by R.F. (Ric) Redden, DVM Many speed and sport horses are plagued with quarter cracks, crushed heels and soft tissue injuries that are all too often chalked up as bad luck and seldom receive the respect they deserve. But what many people do not realize is that quarter cracks and similar foot injuries are the end result of a series of cascading events that occur inside the foot long before the actual injury occurs. By the time these external changes happen, internal damage has already occurred. Most farriers treat and repair these commonly occurring problems to the best of their ability, however any treatment performed without regard to what is happening within the foot often does not address the underlying cause. Therefore these cases often get caught up in a vicious cycle that plagues them throughout their career and sometimes the rest of their lives. The first sign of digital cushion and heel tubule demise is a decreasing palmar angle (PA). While the PA is easily influenced with a rasp, other factors can also cause a decrease in PA. It is often thought that a lower PA is caused by farriers removing too much heel, but this is not so in most cases as the heel can also come off from within the foot, not just from the outside. As crushing begins to collapse the digital cushion, the heel tubules are subjected to excessive load. They begin to fray, then fold inward and forward. Once the cycle has started it can proceed very quickly, especially when horses are training at top speeds. Therefore using the PA as an overall health monitor of the foot helps trainers, vets and farriers have a quantitative means of tracking equilibrium and balance and offers a means of setting a benchmark that reflects optimum health of the foot. By identifying the PA and its relationship to other key parameters such as sole depth and medial/lateral balance, we can develop shoeing protocols that can enhance the health of the foot and maintain the mass, toughness and balance required for intense training programs. Developing our knowledge of the internal mechanics of the foot and how they function allow us not only to manage problems that already exist, but also develop foot care programs that can prevent or minimize their occurrence in the first place. Measuring the Palmar Angle The PA is measured by drawing a line along the palmar rim and connecting it with a line along the ground surface. This angle can vary greatly in healthy feet, depending on age, breed, use, etc. Therefore there is no standard written in stone that can be referred to as a normal PA. A zero PA occurs when the palmar rim is parallel to the ground surface. The negative PA occurs when the wings are lower than the apex. This is also referred to as caudal rotation. When shod with a flat shoe, the PA with the ground surface is the same as it would be if the horse were barefoot. However, when a shoe and/or pad alters the angle of the PA with the ground surface the PA can be referred to as the shod PA. Wedge shoes, wedge pads, rocker shoes and heel elevation shoes create a different PA than what we find in the bare foot. Using the barefoot PA and the very flexible shod PA we can develop a large range of shoes that meet the mechanical requirements of many pathological syndromes. Characteristics of the Negative PA External Characteristics The crushed heel front foot is normally found opposite a club foot. The club foot does not have to be a high grade, as a horse with a low grade 2 club can have a very noticeable low heel on the opposite foot with a thin digital cushion and zero to negative PA. The rear foot that is directly behind the club foot will also have a shallower digital cushion and often a moderate to excessively low PA that can be as much as 10-12 °s negative. The hind foot that is diagonal to the club will be the strongest foot of the four, and is invariably the easiest to maintain with a healthy sole depth of 15+mm and a positive PA. The foot has a very characteristic appearance when in the negative plane, though quick assessment is easier in hind feet than in front feet. The hind foot will have a slight bulge along the dorsal face and the growth ring pattern will be much wider at the toe than at the heel. When a horse with a healthy toe-heel growth ratio is standing with the hind cannon bone perpendicular to the ground, a line drawn along the coronary band slope will strike the front leg at the knee or below. In the negative PA foot, this line will strike the abdomen or flank. Internal Characteristics Having reviewed literally thousands of images before and after shoeing, it is obvious to me that many of our thoughts and concepts of how the bone relates to what we see on the outside of the foot are often contrary to radiographic evidence. Radiographic information is vital to managing horses with crushed digital cushions and a negative PA. To develop an eye for what is happening inside the foot we must study the radiographic image and develop a working knowledge of how it correlates with external landmarks to offer key information concerning imbalance and the cascading series of events that occur as the heel goes into the crushed mode. Therefore farriers need to develop a base for reading and interpreting the relationship of the bone to the hoof and hoof to ground surface. To do this it is important to review farrier friendly radiographs (lateral, low beam with opaque wall marker) on as many horses as possible before and after shoeing and/or trimming. I find this is the only way we can continue developing an eye for the little details that describe the state of health of the foot and the only way we can fine tune our mechanical protocol. Sole Depth Evidence from venograms of healthy shod feet suggests that most horses require a minimum sole depth of 15-18mm to adequately protect the sensitive structures of the foot. This measurement and its relationship to PA are very important and demand great respect from farriers and vets who are focused on pathological shoeing solutions. When in harmony, this relationship provides adequate sole depth and healthy equilibrium between DDF tension, apex compression and lamellar stress. When equilibrium has been lost, a series of cascading events takes place that can quickly put the foot in jeopardy. Many horses and vets disagree with my recommended sole depth dimension as they see a lot of top horses with very thin soles. I would have felt the same way before obtaining information from venograms. Shod feet with a consistent growth pattern heel to toe and medial to lateral that maintain 7-10mm of new horn growth every 30-45 days will have a cupped sole of 15+mm in depth and a slightly positive PA. Venograms of these feet will consistently reveal a full 10mm of vascular supply distal to the palmar rim and remarkable solar papillae that will be in the same plane as the dorsal hoof wall. This benchmark is consistently confirmed with venograms performed with proper technique. Other horses that are highly competitive with 10mm or less sole do not have a healthy vascular supply. Venograms reveal severe compression of the circumflex vessels and solar papillae. Solar papillae, if present, are very short relative to the foot with 15+mm of sole, and the medial quarter will usually have stark loss of solar perfusion in the palmar zone. These horses may appear sound, but they are training with a major vascular deficit. These feet can bruise easily, often develop quarter cracks on the deficient quarter and heal slowly. A close observation of a thin-soled foot will reveal a thin and often shelly wall. Medial quarter growth rings are often stacked up very tightly together, which means the quarter is dormant with no growth. The wall will have 2-4 sets of nail holes as the farrier has run out of places to nail. That is when composites are used to hold the shoe on. When the shoe is removed, the foot side will have deep creases in the heel area in the same place that folded heel tubules sit on the shoe. This high friction area triggers a vicious cycle, as the wall rolls under the foot. The horse actually walks on the outside of his wall instead of the end horn tubules, further crushing the tissue in the heel area. The frog starts to protrude lower than the heel tubules that are constantly being crushed. This foot, commonly found in many training stables, is headed for trouble. This is why I maintain that 15+mm of sole and a positive PA are required for a foot to stay healthy. This is the depth that the horse should have immediately post shoeing, not 4-6 weeks post shoeing. Heavier breeds such as warm blood crosses, etc. require several millimeters more sole depth to provide adequate protection to the sensitive structures. This may not be easy to achieve, but it should be our goal. Medial/Lateral Balance When in medial/lateral balance, the PA of the medial and lateral wing of PIII will be identical. However, when one wing lists out of balance this wing will have a different PA. Medial wing listing can be found in a large majority of horses. While it has been generally thought to be abnormal, I am not so certain this is correct, as it appears to be influenced by conformation and development. The majority of feet that have remarkable imbalance also have stark differences in the shape of the medial wing (observed on the low beam DP radiographic view) relative to the lateral wing. This could be due to remodeling along the lines of stress and/or a genetic linkage. The significance of this finding is relative to the incidence of medial quarter bruising, heel pain, slower than normal horn growth and subsequent quarter cracks that often plague speed and sport horses. The horse that has significant medial listing seldom has adequate foot mass and most often has a crushed digital cushion that produces a negative PA that can be quite severe. This is often the precursor for quarter cracks. It is common to find a negative 6-10° PA in front as well as in hind feet in training stables worldwide. Treating the Low PA Foot Feet are not born equal by any means and do not respond the same to a set standard of shoeing and trimming. Some are destined to be stronger than others within a certain breed and among different breeds. There are numerous ways to aid mass production and mass maintenance, all the while striving to improve balance. We should be more focused on mass than balance as it must come first in order to re-establish a healthier foot. Creating the illusion of balance without accelerating mass often results in a vicious cycle, as the foot becomes weaker rather than stronger. Growth centers must be stimulated in one fashion or another if we want the weak foot to become strong. Simply making it look more appealing to the eye is not conducive to a progressive foot program. Unfortunately, farriers are often expected to fix the weak foot by taking away everything that makes it look weak and sanding or polishing what is leftover. If we want stronger feet we must be focused on mass rather than balance. Much like the club foot we do not have means to cure the low heel, crushed cushion foot, but we do have options that can greatly enhance the health of the foot and help prevent the ill effects that cause all sorts of lameness issues in sport and speed horses. Genetics and conformation play a role in the demise of the heel, otherwise it would be quite easy to fix these cases and keep them fixed. Since this is not the case, we must enhance the mass and then the balance of feet that are programmed to fall apart under the stress of training. The Rocker Motion Shoe Depending on the degree and chronicity of the crushed damage, several options are available for the horse that is out of training. Horses with low scale crushing respond nicely to a 4 point trim, hot sear and a few days protection before going barefoot. For more severe cases, the rock 'n roll concept is a great way to quickly enhance mass. Using the rocker motion shoe to enhance blood flow to the deprived solar corium aids quick recovery of all but non-functional solar papillae, subsequently accelerating sole proliferation. However, the degree of mechanics, how quickly we need the mass and the state of training and/or other ability that is expected of the horse must always be taken into consideration. I prefer to pull a horse out of training for 2-3 shoeing periods in order to gain optimum foot mass over the shortest period of time. Simply eliminating daily concussion to the heavily compromised heel and buttresses starts the natural healing process. The higher the mechanical score of the shoe (1 point for every two degrees it raises the PA), the greater the response. Therefore, if a horse can back out of fast work for a few weeks and use a higher mechanical shoe, a 12-15° PA rocker rail would be my choice. It is not unusual to double or triple sole depth in the first 4-6 weeks following application of the shoe. Many speed horses typically have 5-8mm of total sole depth with zero to negative PA and little or no signs of new growth month after month. The mechanics of this degree of rocker shoe can produce 12-15mm of sole in one shoeing period on this type of foot. Once the growth centers are stimulated the foot starts to quickly reconstruct itself. When healthy foot mass has been re-established, most horses can go back into slow work wearing the rocker rail. However, the new growth is immature and needs conditioning time to become strong and durable. The foot may require mechanical aids to enhance perfusion for several months depending on the response, chronicity and age of the horse. This is the difficult part of foot reconstruction. As soon as sole is 15+mm, PA has improved and the horse is moving great, most trainers and owners want to go back to the flat shoe. But as soon as the DDF is solidly engaged by the action of the flat shoe, sole growth stops and within 30 days the 15mm of sole can be reduced by several millimeters from within. This sounds impossible, but that is the reality. I have witnessed this sudden loss of sole mass many times. Many think that the only way to lose sole is from wear or the rasp, but simply shutting down solar papillae can deteriorate existing sole very rapidly. Weaning the mechanics off of the foot as it heals works well for many cases. I like to drop the self-adjusting PA 3-5° between shoeings until I can use the full rocker shoe, which normally increases the PA 3-5° from the barefoot static image. The next step down is a flat shoe with rocker. This is not a rocker toe shoe; the belly is a smooth radius from toe to heel with the peak of the belly slightly behind the widest point of the foot on the low heel and slightly in front of the widest point on the club or steeper foot. Many horses can wear this style of shoe for many months and compete at any level. This can make everyone happy as it looks more like a regular shoe. However, I have many cases that slowly return to a state of no growth and thin sole when everyone thinks the foot is back to normal and will hold forever. Once the digital cushion has been crushed and the heel tubules have folded under the heel there will always be a tendency for the foot to revert to this state given good reason. Therefore, we must seek to maintain this condition rather than cure it. Note the PA on the bare foot is 3-4°. The shod PA is 10-12° using the full rocker shoe with no added mechanics. This would make the shoe a 4 score shoe, as we have raised the PA 8°. Shoeing Guidelines Many styles of shoe can be used to enhance the rocker motion. The basic points of interest that I hold strongly to regardless of style or discipline are: Know how much PA you can use to meet the desires of the client, all the while gaining optimum recovery. Crushed heels must be pushed back to solid tubules that can be loaded on end. This may put the heels well above the ground surface of the frog. So be it. When the wall is rolled under and the shoe is resting on the outside of the wall, the angle of the foot (between the bars and heel tubules) is under tremendous load and is deprived of adequate circulation, putting it in shutdown mode. Frogs that extend well below the heels can be used as load zones as long as the frog is dry and tough. I put a positive frog pressure bar in shoes for rehab horses, but never speed horses unless the foot is well along in the recovery process. Rocker the toe forward of the apex of PIII. No sole is removed under the apex. I even leave the dirt in this area. The shoe rests on the anterior pillars and heel tubules. When a frog pressure bar is used, the frog carries the majority of the heel load. The tubules just touch when under maximum load. An air space should be seen between the toe and shoe when fitted properly as well as between the peak of the belly and the wall. Do not be concerned about this gap as it will fill quickly with wall and sole. You can fill it if you like; the shoe does not have to fit every contour of the foot to offer accelerated foot mass. Soften the heel branches of the shoe, creating a nice, smooth blend with the heel tubules. This is a very important step as excessive pressure to the buttresses and heel can cause a painful response if the heel is allowed to push heavily into the tender area. Always leave as much foot mass as possible when applying these shoes. The goal is to gain foot mass, not take away from it. Always nail in the center of the belly, not the toe as you would a flat shoe. Center belly nailing allows the shoe to move at the same speed as the horse. Flat shoes often stay on the ground microseconds after the horse has moved. Note excessive nail hole wear with flat shoes. Horses that can be turned out for free exercise while training have far better quality feet and horn growth rate than horses that are stabled for 23 hours a day. The foot needs constant demand for toughness if it is going to become tough. This horse was presented with chronic heel pain. Radiographs revealed no demonstrable lesions other than unhealthy soft tissue parameters. Note the negative 6° PA, thin sole (13mm under the apex and 7mm under the wing), 25° TSA and severely broken back hoof axis. Cumulative ill effects of the extremely low PA coupled with the long digital breakover have contributed to the crushed digital cushion. This would be the low foot opposite the club. Note immediate improvement in digital alignment, which could be further improved with more mechanics in the shoe. Note the positive frog pressure bar. Before and after photographs of the same foot. This thoroughbred race filly was taken out of full training and put in slow training while wearing this rehabilitation shoe. Normally this shoe requires three to six months to reestablish adequate digital cushion and buttress strength. Avoiding Moisture Moisture is a killer for unhealthy feet. Keep the foot dry. Mud buckets around race stables should be a thing of the past. A wet, soggy foot is one headed for maximum crush, and it doesn't take long. I hot sear a lot of tender, shallow feet, especially in areas where moisture is a problem. Hot searing frogs works great to quickly toughen them. Keratex Hoof Hardner is a good product for daily use when moisture is a problem. Bedding on shavings instead of straw helps dry feet up. Venice turpentine on soles keeps them tough. Strong iodine works ok, but is not my preference as it dries out the sole too much and leaves its mark on all radiographs, which can result in a non-diagnostic image when superimposed over areas of interest. Other Options There is a large range of options available, and not all can be covered here. Just remember that the following options are also available, and new concepts are being developed all the time. Buttress wedge Shoes applied with nails along the outside of the foot, secured with Vettec Equi-Thane Super-Fast™ Composite attachment Mechanical boots Prevention The adult foot is the product of how it develops and matures from birth. Development is influenced by the environment, exercise, moisture, conformation factors, farrier care, management protocol, illness and injury. Therefore it is not only the farrier's responsibility to assure that all feet under their care reach and maintain optimum health. One of the most important aspects of a manager's role is to develop an eye for the unique characteristics of feet and the little things that make them so different. They should learn the basic silhouette of radiographs, especially soft tissue parameters and how measurements can influence decision making when it comes to enhancing or preserving the health and strength of the foot. With this base of knowledge, they can better communicate with their farrier and vet. Simply put, all three professionals must have a good understanding of what the foot needs to remain healthy and strong as well as the negatives that constantly eat at the mass and overall strength of the foot. Managers should be alert to the following negatives influences: Overzealous trimming of the frog, sole and horn capsule. Managers often insist on over trimming, thinking it helps avoid problems. We do not gain mass with a rasp. Constantly striving for a sale foot - small, smooth, well shaped and balanced - without regard to demands of developmental requirements, mass or pathology (such as club feet). This type of foot can be established when it is time for the sale, and there will be plenty of foot to work with. Excessive moisture. Lack of exercise and lack of demand for toughness. Manicured pastures with no rocks or abrasive surfaces put little demand on developing feet. There is a happy medium that can be designed into the program. Unruly or difficult to handle horses. These horses get the short end of the stick when it comes to foot care. The farrier's job is a very serious part of the overall foot program, not just something that should be done every 30 days. Training the horse to stand for the farrier is management's responsibility, not the farrier's, as it requires daily reinforcement training, which is vital for any and all optimum foot programs. The most important goal for the farrier to achieve is adequate foot mass. Feet with optimum mass will have stronger, thicker walls and soles when mature. Unfortunately, most foot programs employ frequent trimming schedules that are usually designed to achieve ideal balance without regard to mass. This produces good balance but minimal mass and often results in thin walls and soles, weak bars and heel tubules. This can quickly put a foot into crushed heel mode, even before a horse goes into rigorous training. Using the 4-point trim method to maintain optimum mass and balance with foals, weanlings and yearlings is a great way to help feet develop optimum strength right from birth. Remove only what the foot does not need and leave everything it does need. This is a great way to look at developing feet. The foal's foot really does not need to be trimmed but rather touched up, and a palm sander does a great job for the first few months of life. Young stock raised on manicured pastures that remain wet during early development often have excessive toe growth that does not exceed wear. Therefore breakover slowly moves forward, which can start heel crushing very early in life. I find that breakover is all that needs to be reduced with most foals. Nothing more needs to come off the foot. We don't gain mass with the rasp. If we only remove what a foot doesn't need and promote trimming that helps avoid excessive toe growth, horn breakage and subsequent cracks and abscesses we can enhance the health of all young feet.

The horn-lamellar (HL) zone is another of the five soft-tissue parameters that Dr. Redden measures on his radiographs. The measurement explores the relationship of the face of PIII to the outer horn wall. If you look closely at a true lateral radiograph taken with soft-tissue detail, you will find that an opaque line separates the horn and the laminae. Measuring the HL zone helps determine if pathology in this area involves the horn or the laminae. Use the following steps to measure the HL zone consistently: Step 1 Beginning just below the extensor process, draw a line perpendicular to the edge of the hoof wall. Measure the length of this line in millimeters. Notice the barium paste used for a wall marker. This helps us determine exactly where the outer hoof wall begins. Step 2 Draw a second line from the apex (tip) of the coffin bone perpendicular to the edge of the outer hoof wall. Measure the length of this line in millimeters. These two measurements determine the HL zone. When referring to the HL zone, the top number is given first followed by the bottom number. In this particular case, the HL zone measures 22/30.

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Indepth Equine Podiatry Symposium Notes Written and presented Summer 2010 by R.F. (Ric) Redden, DVM Frequently, the chronic laminitis horse is confused with the acute case, and is often treated the same way. This misunderstanding and misconception continues to stifle progress in the field of podiatry. Many definitions of acute and chronic have been proposed, however when we have working knowledge of the sequence of events that can be clearly identified by a physical exam, radiographs and venograms we can formulate a treatment regimen tailored not only for this stage of the syndrome but for each foot involved. Personally I consider cases to be in the chronic stage after the acute phase has passed through the largest window of response, which normally occurs 4-6 weeks from onset. An exception is the high scale case that goes off the radar screen within the first few days of the syndrome. The feet are physiologically dead within hours of onset and slough in a matter of days. The window of response for these cases is extremely short relative to the average acute case. Chronic cases suffer from the cumulative damage that is caused by compromised blood flow to the vital areas of the hoof. Chronic sole compression thins the sole and erodes the apex. Toe growth all but stops due to dorsal coronary plexus compromise, and the ever increasing PA prevents heel loading, which causes excessive heel growth. The cumulative effects are the result of a cascading series of events that is relative to the damage at onset or efficiency of the emergency treatment and the mechanical protocol that follows. The chronic case is no longer considered a red alert, but certainly demands prompt attention as many cases remain very painful even months to years from onset. Regardless of the stage presented, it behooves us to follow a disciplined, methodical discovery protocol that helps define the degree of vascular, soft tissue and bone damage; determine soft tissue parameters and establish client goals as we formulate a treatment protocol. Case 1: Show horse with pre-symptomatic chronic laminitis This case may have a history of intermittent soreness, though not necessarily lameness, scoring less than Obel grade 1 of 5. The foot may have increased heat and often pulse, usually in one foot, and often stands with the affected foot positioned forward of the other. However, the horse warms out of soreness and continues to compete. This could describe many different problems and is often thought to be quite insignificant when there are no other findings. The lateral low beam, soft tissue radiograph will help confirm that very low grade laminitis is present. There will be no signs of rotation or sinking, but a close look at the HL zone reveals it is 2-5mm wider than it is on the opposite foot. When both front feet are involved, the HL zones can be compared to the hind feet, which will normally be the same as the front feet unless pathology is involved. To further confirm that the wider L side is evidence of low grade laminitis, perform a venogram and compare the findings to that of other healthy feet. The vascular pattern will be quite different. Treatment: Depending on the degree of vascular alteration and the length of time that has passed since the first indications that there was a problem, I treat cases such as this with a medium score rocker rail that provides a 12-15 degree PA and recommend very light exercise and a follow up venogram in 30-45 days. At that time the vascular pattern should be improved, revealing demonstrable solar papillae; a tighter, denser dorsal supply; good medial/lateral coronary and quarter supply and a continuous flow over the extensor process. Sole depth should have increased by several millimeters and horn growth should be accelerated, evidenced by a new growth pattern that should be equal at the medial and lateral quarters unless prior growth history produced otherwise. These cases can respond well to this method of treatment, though several resets using moderate mechanics to aid vascular and soft tissue repair may be required for the best long term results. The training schedule should be kept light until the new horn has grown to the level of the apex, which takes approximately 4-6 months. Closely monitor the soft tissue parameters as the new hoof grows out. The L side measurement should return to normal and the new horn will show a distinctly tighter growth pattern that can continue provided the mechanics that release DDF tension are maintained. Same case, 30 days later. Note HL zone, 20/18mm. This is evidence of the mechanical action of the Ultimates. Case 2: Low scale chronic laminitis This case presents weeks to months from onset with lameness grade 2/5 or less and the following soft tissue parameters: distal HL zone widening of 3-5mm, PA 5-10 degree (depending on prior history when a club foot is present) sole depth 15+mm and no lucent zone along the endodermal/ectodermal junction. Why is the timing of onset important here? Though the same radiographic signs can be visible in the first few days to weeks of onset, the mechanical plan for the acute case will be totally different from the chronic case, as two to three months from onset the acute stage has passed. Capsular rotation and other parameters have basically become static. Treatment:: The good news is the majority of capsular rotation can be reversed with efficient mechanical enhancement that will adequately reduce DDF tension using shoes or Redden Ultimates (as seen in the case below) that greatly reduce DDF tension or various levels of surgical correction, e.g. inferior check desmotomy, DDF tenotomy proximal to the attachment of the check or DDF tenotomy distal to the attachment, depending on the severity of vascular alteration and digital displacement. When there are only a few millimeters of distal L thickening and the case is months since onset, a rocker shoe that produces a 12-15 degree PA is usually adequate to enhance healing. However the case that presents with similar signs that is only a few weeks from onset is treated with high PA enhancement and exercise is restricted. The timeline is very important. Turnout is ok provided the condition is very chronic (months to years) and the horse is not overly active. New horn growth and radiographic evidence of a tighter L zone confirms the efficiency of the shoeing device. Case 3: Low to mid-scale chronic case This chronic case presents with the following soft tissue parameters: narrow lucent zone along the endodermal/ectodermal junction, several millimeters of distal displacement (e.g. HL zone 18/25mm), no evidence of vascular damage to the apex and reasonably healthy sole depth of 15-18mm. Treatment: These cases can also reach full recovery using 12-15 degree PA enhancement shoeing, though some cases may need slightly more mechanics, such as an 18-20 degree self-adjusting PA. Recovery time varies with growth rate, age and breed, but normally the entire capsule will be re-grown in 8-12 months. I like to keep competitive horses out of training for a minimum of a year and a half, preferably two, as this allows the horn to grow out at least twice from the coronary band to ground surface and assures optimum reconditioning and attachment of the endodermal/ectodermal junction. Once full recovery has occurred there are often no gross or radiographic signs of previous laminitis. Case 4: Mid to high scale chronic damage In this chronic case the following soft tissue parameters are present: proximal L zone increase of 5-8mm with distal increase of 10-12mm, adequate but not dense and healthy sole depth, a large PA (15-20 degree) unless the heel had recently been taken down, obviously damaged apex and areas of lucency that can be seen radiographically. The growth pattern indicates accelerated heel growth and very slow toe growth. With all chronic cases the club or steeper foot will normally have more damage than the low heel foot. Therefore, this foot can give you more problems, respond slower and often fail to attain the level of healing of the lower profile foot. Treatment: A venogram may be a deciding factor between shoeing with optimum mechanics or cutting the DDF. Most of these cases will have a well organized lamellar scar that can be seen grossly as well as radiographically. The venogram may reveal a distinct vascular pattern that has been pulled from its ectodermal attachment. There may be some degree of circumflex vessel remaining distal to the apex or it may be prolapsed over the apex. First consider the goals of the client. When pasture soundness is the goal I would consider derotation shoeing with a tenotomy rail or shoe that offers comparable advantages. Create a zero PA with the foot side of the shoe branches while maintaining a minimum 20mm distance between the palmar rim and shoe. The 3-5 degree wedge in the shoe helps prevent excessive luxation when the DDF is cut and offers better articular alignment. This helps prevent excessive load on the vessels entering the terminal arch. The heel extension component of the shoe prevents toe lift that occurs with a fair number of cases and allows the horse to be bedded in deeper bedding. If the heel extensions are left off, most cases will hyper extend the coffin joint in deep bedding. Bandages should be worn for 90 days post op. I often let my chronic cases wear the tenotomy shoe for 8-12 weeks provided the length does not pull the foot forward, creating a tip up situation. At this time sole depth should be 15-30mm (depending on the starting point) and the DDF will be securely adhered to the SDF, which allows the foot to be trimmed to a minimum sole depth of 20mm and a 2-3 degree PA when possible, and left barefoot. Toughen the foot with a propane torch and Keratex hardner or apply a bandage or a boot for a few days until the foot gets into a tougher mode. These cases do well barefoot provided there is adequate mass. This case may also respond well to an 18-20 degree PA shoe, however there are pros and cons for either option. Shoeing Shoeing requires a farrier with good working knowledge of radiographic information. Sole depth, PA and digital breakover are all very important parameters to be considered when applying a rocker shoe. The shoes are technique sensitive, therefore knowledge of the degree of mechanics that are required and how to apply the shoes are vital. Shoeing intervals can vary from 30-60 days but must be consistent. Radiographic control is necessary for each shoeing. Failure to monitor the efficiency of the mechanics, response, etc. can be very detrimental to a successful outcome. Therapeutic shoeing with radiographic control is not cheap and requires a substantial investment that should be considered before starting the protocol. There is no cheap shortcut way to push these cases to full or even an acceptable recovery. Shoeing can offer favorable results, however the results may be a bit slower to attain than with a tenotomy. Shoeing is recommended over surgery for mares heavy in foal, or mares with young foals that need to go out. Surgery Initial investment is greater, but can be more economical long term. Requires proper shoeing prior to mid-cannon DDF tenotomy. Surgery can be performed standing with sedation and local block. Follow up care requires good horsemanship skills, such as bandage changing. Adequate sole depth can often be obtained in 6-8 weeks. Case 5: Penetrated chronic case 6-8 weeks to months from onset In these cases, one or both feet may be penetrated through the sole and the horse will be grade 3/5 lame on a good day. The hoof capsule will be distorted and steadily become more distorted with longevity. Radiographs may reveal evidence of chronic abscesses, especially in the steeper foot, and minimal to moderate bone damage. The HL zone may indicate sinking and rotation that occurred months prior to penetration, and PA may be 10-20 degree, which is higher than normal for the feet presented. Treatment: These cases all require derotation/DDF tenotomy if you are seeking optimum recovery with minimal damage to PIII and growth centers. Many professionals believe that they can attain pretty good results without cutting as many cases as I do. But how we determine whether or not a case is successful varies greatly. I personally consider cases to be successful when there is no further evidence of the disease, sole depth and PA are easily maintained, growth patterns are compatible with that of a healthy foot and the horse is pasture sound and can be ridden lightly or even go back into full training and slow sports 2-3 years from onset. Thirty years ago I was satisfied that if a horse remained alive, regardless of how crippled, they were a success and I attempted to reverse the irreversible for months on end. That has all changed with experience and unprecedented numbers of cases. The advent of venogram information and astute observations of small details clearly paved the way to my present and most beneficial treatment protocol. I cannot stress enough that time is of the essence. Case 6: Very chronic high scale case: This case may present with extensive hoof capsule distortion and be grade 4/5 lame or reluctant to stand. The HL zone can be off the scale (25/40mm), sole depth may be only a few millimeters, and PA can be 30-40 degree. The horse has a history of chronic abscesses and extensive bone deterioration within the level of the nutrient foramen. Treatment: This stage of laminitis has short term solutions at best. Most cases are very lame, have evidence of prior or existing body sores and are down more than they are up. They certainly meet the criteria for euthanasia, but with select cases when the owner wants to do everything possible to make the horse comfortable and can financially support all efforts, derotation followed by DDF tenotomy often offers immediate relief for a few months. However, due to extensive bone disease most cases will have recurring DDF contraction, scar contracture and SDF contraction, which can be observed as heel growth rapidly exceeds toe growth, the PA continues to increase and the horse knuckles forward at the fetlock. The fetlock goes forward first due to pain response, but when it remains forward the knuckling becomes more permanent. This stage often follows many of the mid to high scale cases that slowly deteriorate over the years and is normally always associated with the previous, ongoing degenerative bone disease. Case 7: Advanced stage chronic laminitis This stage of laminitis will have moderate to extensive bone disease, a large PA, thin sole, large HL zone especially at the distal measurement, upright pastern and knuckling at the fetlock. These cases may have had previous DDF tenotomies several months prior to presentation. The club foot will invariably become upright and knuckled forward some time before the lower heel foot undergoes similar changes. Treatment: Twenty years ago I thought it best to re-cut the DDF and also the SDF on these cases. However, the end results were often very disappointing. When both tendons are surgically severed, the suspensory is the only support to the fetlock and the sesamoids are very fragile due to months to years of non-use. The upright pastern does not allow suspensory loading, therefore the sesamoids lose strength and often fracture once the DDF and SDF are severed. Even when using a sling to control load and a cast to prevent hyperextension, bilateral sesamoid fractures are common. They can heal with several months of casting, but unfortunately even when successfully healed the ongoing contraction/contracture phase continues and 6-12 months later many of these cases will once again go upright and knuckle over. A second option is to use a shoe that satisfies the requirements of the DDF and SDF, which can offer favorable long term results. This shoe is made from flat plate aluminum and has a zero PA with the shoe surface and an identical shod PA as the start model. We are not dropping PA, simply shifting load from the apex to the heel. This shoe also has a toe extension that satisfies the action of the SDF. Extending the toe helps push the fetlock into a better flexed position. This can only occur if DDF tension is adequately reduced. Applying a bandage with a cast that extends from the heel bulb to the carpus is also helpful. Once the cast has been on for 4-6 weeks, a half cast along the posterior side of the limb is used for another 4-6 weeks. At this time there should be adequate sole growth and 5-10 degree extension through the fetlock joint. I have maintained several cases for many, many years using this type of shoe and cast combination. Deciding whether to use mechanical shoeing or the surgical option can be difficult for those with limited experience with the many phases of laminitis. As a rule of thumb, the case that is presented with minimal pain in spite of extreme displacement and hoof disfigurement is a shoeing candidate until proven otherwise. On the other hand, the case with unrelenting pain in one foot or all four is normally a surgical candidate even when the parameters are not necessarily off the scale and hoof distortion and bone damage is minimal. When shoeing the chronic case, strive to use mechanics that greatly reduce breakover (rocker) and also allow the horse to stand with the same PA once shod even though a zero PA has been created between the wings and posterior quarter of the hoof at the heel. The shoe should not reduce the PA with the ground surface, as this defeats the purpose of mechanical shoeing. We are simply shifting load. Taking 10 degree PA away from a foot in an attempt to make it look non-laminitic can be devastating, as the forces at play are greatly increased. Shoeing the chronic case for surgery is a totally different mechanical setup. We want to create a zero PA with the wing and shoe branch at the heel and provide a 3-5 degree wedge to create a slightly positive shod PA. This greatly helps reduce luxation of the coffin joint and helps release load on the terminal arch vessels. Regardless of whether shoeing or surgery is the best option for your horse, the big message is this: the majority of chronic cases are chronic simply because they have passed the most effective window of response. Most cases do not have to reach this point. Timely, thorough evaluation and efficient emergency treatment at onset coupled with an effective monitoring protocol that can evaluate the horse's progress (or lack thereof) can reverse the forces at play before irreversible damage occurs.

1996 - 10th Annual Bluegrass Laminitis Symposium Notes Refurbishing Poor Quality Feet Written and presented January 1996 by R.F. (Ric) Redden, DVM The first step for successful foot refurbishing is goal setting. All parties involved have either a negative or positive influence on the end result. Discuss in detail the desired image, use of the animal, and set short term realistic goals from one shoeing to the next. If these goals are not met, regroup and clarify the problem. Positive results are the product of good planning and the execution of skills. I must agree with Dr. Doug Butler that "the power of observation is our most valuable tool", and skill is meaningless without it. There are basically two schools of thought for refurbishing poor quality feet. 1. Quick Fix: I refer to as "The Band-Aid Technique", offers immediate cosmetic appeal and often results in a favorable response which is relative to the condition in which you started. I often hear "You should have seen this foot when it came to us", and I have been guilty of saying the same. Evaluating the craftsmanship of any shoeing job immediately following shoeing has many pitfalls. Most all pathological conditions related to mass and balance steadily deteriorate over the next few weeks. Evaluating a job at the end of a given shoeing period often leads one to believe the job performed was performed incorrectly, a very unfair assessment. For years I asked myself, why does the quality of the horn often deteriorate, in spite of consistent, regular good shoeing? Being critical of my work, I developed a simple observation plan with each follow up case. Is the foot better, the same, or worse than it was following the last shoeing? Failing to meet the requirements of load, balance, mass and function invariably results in loss of form and produces undesirable side effects. Quick fixes certainly have their place in our profession but we must remember, payback can be devastating. You can pinch hit and quick fix on a weekly basis and squeeze a few more miles out of a foot, but when you have exhausted the Band-Aid option in the peak of the season, you have but one option, shut down. Careers are shattered and millions lost annually from sore, unresponsive feet. How can we avoid the risk associated with the quick fix? 2. Natural sculpturing is a method that offers consistent favorable results on a daily basis. This method relies on the natural load sensors of the foot that apparently transmits a strong message to the growth center. Once properly stimulated, strong horn mass quickly replaces weak, thin, dysfunctional horn. This method is best referred to as "Sculpturing for Tomorrow". Cosmetic appeal can be maintained as well as desired foot flight with this method. It is the natural consistent replacement of horn mass that verifies that there are no true poor quality feet. All feet will respond, some quicker than others, and the response is good for the first stage (five to ten days). When examining a case I like to start by assessing the current trimming or shoeing method. Sort out all the good and bad points. Observe the physical condition of horn and identify all areas that appear to be weaker as the shoeing period progresses. Even though we may not have answers that would withstand the challenge of scientific studies, we can eliminate most all aspects of the shoe or trim in order to assure a favorable response. I prefer the philosophy of leaving every bit of the horn the horse needs and taking only what it does not need. With this concept, the actual work is cut in half and the thought process doubled. Relying on keen observation to guide the knife and rasp offers a consistent chance for natural recovery. Horn, mass and balance steadily improves throughout the shoeing or trim period and favorable results are quite evident four to six weeks later. This approach allows us to develop a new mindset for basic requirements. There are three basic problems that consistently create poor quality feet: 1. Excessive Breakover: Anything that lies anterior to a perpendicular line, 1" to 1 1/4" in front of the point of the frog. 2. Bent Heel Tubules: Loading the heel tubules on their side has serious side effects. 3. Excess Moisture: Capsular horn is rigid and durable when the water content is quite low and becomes very weak and unresponsive when water saturated. Basic Principles of Restoration Support the horn tubules at the posterior pillars. Rasp the heels back (from the point of the frog back), until the bent tubules are straighter. This will be at the widest point of the frog. Using this technique, it is quite easy to increase the support surface of the hoof 1" to 2". I prefer the term "push back" verses "lower the heel", as many trainers become confused when they think you are lowering the heel on a horse that seems to have no heel. Simply put, if you want a heel to be strong and durable, the tubules must be loaded in a manner that enhances pillar function. Determine the depth of sole without taking any of it out. Trim a small area around the apex, down to the frog-sole junction. This is a helpful technique when soles are quite thick and hard. At this stage, it is time to determine whether to apply the four point shoe or go straight to the four point barefoot trim. Several factors must be considered at this stage. The principles of load and breakover will basically be the same with or without the shoe. Performance horses that have reached the limits of quick fix and are forced into a short rehabilitation period will need to be shod because the rehabilitation period is too short to fully utilize the effects of the four point trim. High profile stallions, mares and show animals, that have to frequently meet the public eye approval, will need temporary shoeing as well, to avoid unacceptable tender feet. Those with extremely thin soles and minimal mass will need shoes for a short while as well. The four point shoe offers reasonably quick results, protects the sensitive sole and can be adapted to all breeds. The shoe, regardless of breed, is designed in such a fashion that breakover is 3/4" to 1" anterior to the apex of the frog. Covering the horn tubules to the widest point of the frog, the 4-point shoe enhances medial-lateral breakover, reduces stress on the nails and consequently weak walls. The open heel offers a more natural dynamic heel action, especially when used in conjunction with arch support. The breakover properties of the shoe allow the farrier to use a very small nail, reducing further damage to the walls. I prefer aluminum, as it is very light, 1/8" drilled holes to accommodate a 1 1/2" race nail is sufficient for most all feet, regardless of size. The drilled hole offers minimum wear, optimum pitch and placement. Nails that seat super tight, cause little or no damage to the horn and do not create excessive hole wear. Once the feet are shod, the horn must be kept at a very low water content. Stiff horn apparently picks up a specific signal and transmits a positive message to the growth centers. Water soaked horn will collapse under load and has little or no recall. I prefer Keratex Hoof Hardener as an aid to creating consistent tough, rigid horn. Hot seating is helpful in the early stages of breakdown but seems to cause excessive drying when the horn wall is open with multiple fissures and cracks. Four point shoeing stimulates horn growth, making it essential to reset every three weeks for the first few shoeings. Breakover will migrate forward 3/4" to 1" in three weeks, requiring frequent touch ups to maintain the new response. The downside of the four point shoe over the four point trim appears to be relative to natural signals to the pillars. The shoe invariably traps moisture, bacteria and debris and interferes with natural ground horn stimuli. The typical poor quality hoof, whether still on the circuit or retired for breeding purposes, has a typical appearance. The ground contact at the heels is 3/4" to 2" forward, at the widest point of the frog. Breakover is 2" to 3" forward of the apex. The bars are basically nonexistent and the heels are folded under and forward. The clinches are raised and wall texture is like swiss cheese. All these dysfunctional areas are apparently due to the result of improper pillar loading, horn growth and maturation. All can be corrected over a period of four to six months. Attempting to refurbish extremely poor quality feet for several years has led me to question the validity of the eggbars and extremely full shoeing at the quarters. It is apparent to me that eggbars are great support for the suspensory apparatus of the limb but they do not support the heels. Close observation will reveal increased bending of the tubules the longer the eggbar extends out the back. The horse may appear sounder and look great when freshly shod but has the same deplorable heels within six weeks. (All bars appear to prohibit natural action of the frog, sulci and bars which play a major role in reconstruction.) It has been said "That eggbars distribute load". Sounds good, but what do they tell the load sensors when the horn tubules touch the shoe 2" to 3" forward of its most posterior border of the bar? It is apparent from the wear on the shoe, as well as the frayed nature of the horn tubules, that a serious force is concentrated over a small area of the shoe. The bar is often embedded in the base of the frog, which indicates a lack of support. When wedges are used with eggbars, the tubules often become even more bent. Very full shoeing seldom improves horn mass and quality, leading me to question the validity of increasing the medial-lateral breakover which adds additional stress to the horn wall, clinches and lamellar attachment. Rocker toed eggbars - Do they continue improving the foot with each reset? The location of the rocker in relation to the point of rotation is very important. Most poor quality feet cannot be fitted with a rocker toe shoe, placed at the point of rotation, as mass is at a minimum and there is not adequate sole or horn. Placing it well in front of the dynamic breakover is helpful, certainly over that of a flat shoe, but it fails to stimulate continual restoration of mass. Arch support appears to play a major role with natural reconstruction. Mud and debris that packs tightly into the sulci must surely play a major role in hoof health. Ground surface contact along the angle, sole, bars, sulci and frog offer a tremendous uplift that apparently enhances heel function and reduces stress to the wall and sensitive attachment. Placing a bar across the area, regardless of reason, appears to interfere with heel function and preludes maximum mass development. Placing a bar across the heels appears to reduce the possibility of uplift support. Included are a few diagrams of the shoes I use with most all reconstruction. This basic shoe has many adaptations that can meet the demand of most all breeds. I hope you find it to be as valuable a tool as I have.

Dr Redden's Equine Podiatry Series In-Depth Laminitis Venogram Technique, Indication and Interpretation Written and presented November 2005 by R.F. (Ric) Redden, DVM (Watch the Digital Venogram video performed by Amy Rucker, DVM.) Introduction I developed this clinical protocol out of the need to better understand the degree of vascular damage during different stages of the syndrome. Working with Dr. Chris Pollitt at my clinic, we used his in vitro study to perform the first in-vivo venogram procedure in 1992. It was conducted on a standardbred filly that was owned by the International Equine Podiatry Center. Since that time, I have modified the procedure to meet the requirements of specific breeds, as well as a variety of foot problems that involve the circulatory system. Basic Steps Sedate the horse.Block the feet just above the fetlock. Use only 4-6cc of blocking agent to prevent transient edema.Place the horse’s feet on approved positioning blocks. This will insure a pure lateral projection.Set the x-ray machine in place, and have all the necessary cassettes and grids within arm’s reach.Take a scout film with soft-tissue detail, using a barium paste marker on the face of the hoof wall.Wrap 4” Elastikon around the fetlock. This will provide an anchor point for the tourniquet and will prevent twisting the skin while applying the tourniquet.Place a tourniquet over the fetlock. Avoid a mid-cannon tourniquet.Catheterize the palmar vein using a 5/8”, 21-gauge butterfly catheter. Be careful not to thread the needle too far into the vein. You risk making a second hole in the vein.Inject 20cc of Reno-60. I recommend using two 12cc syringes instead of one 20cc syringe. A 20cc syringe builds too much back pressure and complicates injection. Injection needs to be completed in less than one minute, as the contrast will leak from the vessels quickly and skew your interpretation.Pull the knee forward slightly while injecting the second syringe. The heel should remain flat on the block. This rocking assures lamellar perfusion and unloads the deep digital flexor tendon (DDF).Clamp a hemostat on the catheter, or apply a stopcock. Quickly tape the hemostat to the leg so it will not be in your way.Take your series of film. This series of film should be completed within 45 seconds.Lateral, soft exposureLateral, hard exposure with gridDP, hard exposure with gridDP, soft exposureLateral, soft exposureSoft exposures are needed when there are significantly compromised vessels. Hard exposures offer a diagnostic image of the terminal arch and deeper vessels. The last DP view offers a look at vascular leakage that may not be apparent in the first couple film. Acute and chronic cases will exhibit similar patterns, yet there are distinct differences in the two.Remove the tourniquet and place cotton or gauze over the vessels. Tape in place for 5-10 minutes.Indications A venogram is a discovery experience, as it offers a means to track the disease syndrome as it alters the vascular supply. Therefore, it offers unlimited options concerning the medical, surgical and therapeutic regimes necessary to revive the compromised areas. Venograms can be used diagnostically for: LaminitisWhite Line DiseaseKeratomasPuncture Wounds Having performed a few thousand venograms over the years, I have discovered a pattern that appears to be repeatable as laminitis progresses from a mild onset to high-scale cases; whether it is acute or chronic. Likewise, the venogram offers a reliable means of monitoring the progress of reperfusion in compromised areas. They also help explain why some cases fail to progress in a favorable fashion. Being able to correlate the altered vascular pattern with the clinical picture, growth pattern and tissue response greatly enhances your insight for the planning and treatment stage. Before this unique discovery experience can be used to reveal how badly areas are compromised, we must first learn the range of norm for specific breeds and age groups. The lateral and DP views are the most valuable views when dealing with laminitis. The 65º, DP reveals another perspective when looking at the circumflex vessel and fimbriae, but this view is not vital for assessing the damage caused by displacement. Lateral View Points of Interest The normal foot will have a dense, uniform contrast pattern over the extensor process. I refer to this as the “waterfall.” These vessels continue down the face of PIII in a relatively parallel plane to the bone. Approximately 8-10mm proximal to the apex of PIII, these vessels meet and join the branches of the circumflex network. This network supplies blood to the palmar surface and the rim of the bone. The normal, healthy foot has 10mm of vascular corium ventral to the palmar surface of PIII. The fimbriae are clearly seen penetrating the sole proper. The fimbriae are of great interest, as they are the first vessels to be compressed or crushed as PIII descends, whether it occurs from rotation or sinking. Sport horses that become foot sore, have thin soles and poor quality horn walls. They often have no more than 6-10mm of soft-tissue space between the palmar rim and the foot side of the shoe. In this case, the fimbriae are not visible on a soft-detail venogram, and the major vessels are compressed tightly between the bone and hoof wall. This may be one explanation why short feet stop growing at a normal rate. Therefore, I conclude that a healthy sole requires a minimum depth of 15mm; 10mm for the vascular network and a minimum of 5 mm for the non-sensitive, protective sole. This information should be of particular interest to farriers who strive to maintain a healthy, sound foot. When a foot is trimmed short, small red dots appear along the freshly trimmed sole. These dots are the ends of the individual fimbria. A healthy sole (20mm) will have longer fimbriae than a sole that is only 15mm in depth. This may explain why a long foot will bleed much easier than a short foot that is trimmed to within 15mm of the palmar rim. The lamellar vessels can be seen superimposed over bone as they coarse downward from the coronary band to the palmar surface. The hard penetration radiograph clearly reveals the terminal arch as it supplies blood to the bone. If you examine the coffin bone, you will find small nutrient openings along the face of PIII. These openings allow interior vessels to emerge from the bone, linking with the lamellar network. The more upright, sturdy and apparently healthier hoof has fewer and smaller holes than that found in a low-heel, thin-sole horse. The terminal arch appears to be a major vascular reserve for the bone and laminae, as it can be seen filling even when the dorsal vessels and circumflex network have collapsed. Once the nutrient supply to the bone is gone, the bone no longer has a chance for survival. DP View Points of Interest This view helps evaluate the flow pattern over the medial and lateral aspects of the coronary plexis and the circumflex vessels dorsal to the palmar rim. Often the sound, healthy foot that toes outward will have a diminished flow medially over the coronary plexis. Likewise, if the foot toes inward, there will be a diminished flow laterally. This leads me to believe that this is a load-induced deficit. Many sinkers will list to the medial side, which compresses the coronary supply and the circumflex zone. When they recover from the episode, a very distinctive, deprived growth pattern can be seen along the medial coronary band. In addition, the palmar rim often loses considerable bone due to pressure necrosis. This zone of necrotic bone typically becomes septic and is manifested as a full-blown abscess that migrates to the coronary groove. This focal coronary band separation is often mistaken as sloughing of the hoof. Overall Points of Interest Placing the tourniquet over the sesamoid is more dependable than placing it mid-cannon, as it is difficult to shut down the vascular supply that is well protected between the tendons and bone. Performing digital hyperfusion with the tourniquet placed mid-cannon has questionable efficiency simply because it is susceptible to tourniquet failure. It is a misconception that mid-cannon tourniquet placement adequately and consistently prevents blood flow to the digit. Without the advantage of contrast media to reveal what actually happens, we would have no reason to question this thought process. In my early studies, I found that 50% of my venograms failed to be diagnostic due to mid-cannon tourniquet leak. Trainers also dislike having the tourniquet placed tightly over tendons, and justifiably so. Therefore, the mid-cannon placement has been abandoned. It is relatively easy to determine when tourniquet leak is present, as the contrast will be visible up to the tourniquet. A properly applied tourniquet will completely preclude the arteries and veins. Radiographs will reveal 2-3cm of non-filled vascular space just below the tourniquet. Apparently the contrast compresses the blood, pushing it to the limit of the tourniquet. A healthy foot will have the arterial supply filled retrograde. The arteries will appear as a long strand of beads. The contrast apparently affects the perineum of the vessel wall, causing spasms along the entirety of the vessels. Reasons for Technique FailureTourniquet leakPerivascular injectionFailure to inject the contrast in a timely fashionFailure to take all necessary views in 45 secondsHorse steps off of the blocksForgetting to rock the leg to allow for total perfusion of the dorsal vesselsRemoving the catheter prior to taking radiographsInadequate nerve blockVenogram Interpretation The range of norm is quite varied, as the vascular network is influenced by load, anatomical variations and pathology. Pathology also has a broad definition as sound horses are often found to have compromised blood flow in areas where other horses have a more prominent, well-filled network. Strong, healthy feet have unique characteristic differences, but all seem to have common anatomical, vascular similarities. Being able to identify a healthy foot requires good experience and an eye for minute details. Hoof angles are reflections of coffin bone angles, which are influenced by breed as well as congenital and acquired foot problems. Therefore, to speak of our ideal hoof angle we must consider the bone angle, as all healthy feet will have a parallel relationship between the face of the wall and the face of PIII. The efficiency of horn growth centers also influences the mass of the heel. The digital cushion and sensitive frog rely upon the protection of the horny, heel mass. As a complex unit, all major zones are dependent on the nutrient blood flow. The rate of wear and growth influences, and often alters, the mass of horn protection thereby challenging the integrity of the vascular supply. Trimming and shoeing also greatly influences the perfusion to the digit as the mechanics of the shoes can alter mass-load distribution and nutrient supply to vital growth centers. Whenever the nutrient supply to the solar plexus is compromised, sole growth is diminished. Once the sole becomes thin, the wall also becomes thinner and more fragile. Venograms reveal a typical compressed circumflex zone in horses with less than 15mm of sole depth. When the fimbriae are diminished in length or no longer exist along the palmar surface. Pathology exists even though the horse continues to train in a reasonably sound fashion. This is a normal finding for many speed horses, but far from being a healthy venogram. The scope of this paper is intended to cover the basis for interpreting venograms. A few examples of low to high-scale cases follow. Consider a healthy, strong foot that would have these soft tissue parameters: Left FrontHorn-Lamellar (H.L.) Zone 15mm/15mmSole Depth (SD) 20mmPalmar Angle (PA) 5ºBone Angle 50ºCoronary Band-Extensor Process (CE) 8mmDigital Breakover (DB) 25mm Adding the bone angle of 50º to the palmar angle of 5º means the hoof angle is 55º. The opposite foot is slightly mismatched with the following measurements: Right FrontHorn-Lamellar (HL) Zone 15mm/13mmSole Depth (SD) 20mmPalmar Angle (PA) 1ºBone Angle (BA) 48ºCoronary Band-Extensor Process (CE) 15mmDigital Breakover (DB) 30mm One would suspect the hoof angle to be 49º, but with the toe backed up hard (note the 15/13 HL measurement), it can actually measure up to 52º. Toe angles only reveal a small part of the big picture. Farriers are often asked to match toes angles on horses with discriminating palmar angles. This often leads to a series of cascading, negative results. Taking these measurements into consideration with every lateral view on all feet will quickly build a database that helps define the range of norm, and how the foot was last trimmed. The left foot from above will have uniform, well-defined fimbriae patterns along the palmar surface. The fimbriae will continue along the terminal laminae in the same plane as the face of the bone. When the early stages of laminitis alter PIII placement, the fimbriae will be bent forward due to the download. These early, but subtle, signs of instability can be clearly assessed from a venogram days before significant displacement of PIII can be measured. The return of the fimbriae following adequate mechanical and therapeutic treatment can also be demonstrated within days of a progressive response. The right foot from above will have a slightly different fimbriae pattern. They will be slightly longer along the toe area and significantly diminished in length from the widest part of the foot to the heel. The growth ring pattern of the hoof wall will confirm that more toe growth has occurred than heel growth. The digital cushion will also be compressed, while the heel tubules will be folded forward with limited structural stability. As a rule, laminitis appears to have a more detrimental effect on the steeper of the two feet, and it should be the primary concern of the vet/farrier team. A mild onset may simply alter the direction of the fimbriae, but this is very significant. It demands immediate mechanical therapy to reverse the forces at play. Mid-Scale Damage The mid-scale case will have an increasing HL zone from the onset. This is your first clue that this case is going to be tough. Closely monitor the HL zone! The circumflex vessel will be compressed tightly against the palmar surface of PIII. The first lateral film taken at onset becomes very valuable as you track the progress or deterioration of the case. What if a speed horse that won his last race had 6mm of sole depth, a 2º to 3º PA, and a very upright pastern, then became lame? The compressed circumflex on a super thin-footed horse will appear somewhat different than a compressed circumflex vessel caused by displacement. The sole proper is much thinner and the shortest of feet will not displace the vessels proximal to the palmar rim. Performing many venograms on thin-footed horses will help you distinguish “no foot compression” from “displacement compression.” When the vessels are acutely compressed 8-10mm, the horse is normally very lame, as the coffin bone is cutting through the sole corium. Basically, this is trapping the circumflex vessel between the wall and the palmar rim. At this stage, the vessels become dysfunctional. There may be a slight forward projection of the circumflex, which defines the folding nature of the network as PIII pushes distally. The coronary vessels may show reduced flow over the extensor process and the medial coronary plexus may have a stark loss of contrast. The terminal arch will appear quite normal. This degree of damage may occur within hours of the syndrome, or it may take several days of slow displacement. Either way, it should be considered an emergency and demand great respect from the vet/farrier team. The new goal is to unload the compressed zone mechanically. The sooner this is accomplished, the better chance the thin palmar rim will remain viable. High-Scale Damage Once the circumflex vessels are displaced several millimeters and prolapsed over the apex, very serious compromise exists. Considering most healthy feet have 20mm of sole with 10mm of vascular space beneath PIII, when the vessels are 5mm proximal of the apex, 15-20 mm of displacement has occurred. The CE will reveal an increase of 15mm, the sole depth will decrease by 15mm, and the HL zone will be increased by 10-15mm. All high-scale cases will experience a rapid increase in the HL zone. Very serious cases that swell 10-15mm within 24 hours will have stark loss of contrast down the face of PIII along the palmar surface, and significantly diminished supply in the terminal arch. The coronary plexus will be broken. The proximal coronary plexus zone will remain intact, followed by a separation over the extensor process. This zone will match the distance the CE has increased. High-scale cases require aggressive therapy, in addition to derotation shoeing and decompression of effected areas. A DDF tenotomy is most always indicated. A partial or full wall ablation and pin cast may also be viable options. Venograms will often reveal stark loss of contrast along the medial quarter. The circumflex vessel will be absent in this area. Occasionally, there will be a very similar picture along the dorsal vessels. When there is no contrast in specific zones, I decompress these areas by performing an aggressive wall ablation. Often high-scale cases reveal stark loss of contrast throughout the hoof area, it appears like a tourniquet has been placed around the coronary band. There will be a small area of the heel bulb that will perfuse, even when the foot is sloughing. The terminal arch will be absent as well. Once the nutritional supply to the bone no longer exists the prognosis is very grave. Amputation of the digit is the only other option for cases that has total vascular shutdown to the soft-tissue and bone. Using the very basic parameters to help you plan your treatment options can greatly enhance your ability to treat this disease, as well as become a valuable prognostic tool. Successful treatment of laminitis requires: Timely, accurate assessment of the damage to the digit. The history, clinical examination, radiographic parameters and venograms are vital discovery exercises.Timely, effective reversal therapy. The mechanical, therapeutic and surgical protocols are based on the evidence provided by the discovery exercises. This evidence varies greatly based on the degree of damage.Adequate financial commitment, which is also relative to the degree of damage.

The palmar/plantar angle is one of the five soft-tissue parameters that Dr. Redden measures regularly as part of his radiographic protocol. This angle can be accurately measured on a true lateral radiograph and is useful when designing a treatment regime for a number of foot pathologies. It is important to remember that palmar refers to front feet while plantar refers to hind feet. The simple steps below will help you measure the palmar/plantar angle. Step 1 Locate the wings of PIII. Step 2 Beginning at the heel, draw a straight line underneath the wings and along the solar surface of PIII. Extend this line until it touches the ground surface. Step 3 Draw a straight line at the ground surface or one parallel to the ground surface. Be sure this line and the line you drew in Step 2 intersect. Step 4 Using a protractor, measure the angle where the two lines meet. In this case, the palmar angle is positive 10 degrees. Negative Palmar Angle In some instances the palmar angle can actually be negative as shown in this case.

Banana Shoe The rock-n-roll shoe is also known as the banana, plantain, platano, rocker, or convex shoe. The term "rock-n-roll" is a concept that refers to the process of rockering or applying a belly to any of our four point shoes. For example: Most commonly we will take a 4 point rail shoe and rocker it or shape it like a banana after reading radiographs and determining the palmar angle and where we want breakover to be. The radiographs below show before and after. The same can be done to our 4 point, 4 point race, and 4 point club shoes. The picture above shows the radius or the amount of rocker in a race shoe when looking at the ground surface side. We have also added a Full Rocker shoe that is manufactured with a belly or rocker shape. This makes the shoe more user friendly because the foot side remains flat and the ground surface side is rockered.

HOW TO PERFORM A VENOGRAM OF THE EQUINE DIGIT Written November 2003 by R.F. (Ric) Redden, DVM Take Home Message: A venogram of the digit offers invaluable information concerning venous as well as arterial perfusion. It has value as a diagnostic aid, prognostic indicator and possible therapeutic application. The technique is a low risk procedure, easily performed on the standing horse. (Watch the Digital Venogram video performed by Amy Rucker, DVM.) Introduction: Circulatory contrast studies are commonly used as diagnostic aids for a multitude of maladies in the human field but a reliable means of assessing circulation of the equine foot has not been reported. Hertsch's1 work with angiograms and Pollitt's2 experimentation with venograms became the stimulus for the author to develop a safe, consistent means of assessing the circulation of the equine foot. Dr. Hertsch indicated that general anesthesia was required for angiogram studies as vasospasm was a major problem in the standing horse. Using invitro models, Pollitt was able to fill the arterial supply retrograde via the common digital vein using a tourniquet proximal to the injection site. Redden and Pollitt collaborated in 1992 developing a reliable technique for the standing horse as a great need existed to better understand the parody of circulatory maladies involving the equine digit, especially with laminitis. As an intermediate hypothesis it has been thought that shearing and compressive forces of the third phalanx, once displaced within the capsule, contributes to mechanical circulatory collapse, directly influencing varying degrees of osteitis of PIII3, associated with this observation was the fact that the circulation of the digit could be assessed with in vivo models and the influence of various therapeutic devices assessed4. The etiology and pathogenesis of laminitis continues to be controversial and not well understood. A venogram offers a means for assessing the circulatory system of the digit at various stages of the syndrome. his information helps the veterinarian and farrier develop a protocol designed to mechanically and therapeutically address the forces at play that directly restrict perfusion of the digit. It also can be used as a diagnostic tool for soft tissue and space occupying lesions such askeratomas, tumors and scars. Comparative venograms can become valuable prognostic indicators and clinical observations suggest they may have therapeutic value as well. This paper describes how to perform a venogram in the standing horse and indications and results of specific cases. Materials & Methods: Initial studies were designed to develop a reliable and consistent technique using sound animals in an effort to establish a base line for normal contrast patterns.A variety of pathological foot problems were then examined, including acute and chronic laminitis with varying degrees of damage; club feet in young and mature animals, chronic quarter cracks, keratomas, white line disease and feet with severe imbalance. The standing horse is sedated with 25 mcg Dormosedana I.V., and the foot desensitized with Carbocaineb , 6cc., placed subcutaneously over each common digital nerve just proximal to the fetlock.With bilateral problems the opposite foot is desensitized as well to facilitate quick manipulation of the studied limb.Shoes are pulled, and the feet thoroughly cleaned of all foreign material, taking care to remove all debris, especially along the deep sulcus of the frog and buttress area.The pastern is clipped and aseptically prepped.Each front foot is placed on a wooden positioning block (3x5x7), with a wire embedded along the long axis of the block to delineate the ground surface. Elastikonc is placed over the fetlock to prevent tourniquet slippage. A 21 gauge butterfly catheterd is inserted in the digital vein followed by placement of a tourniquet over the fetlock.To minimize back pressure, two separate 12cc syringes are used to deliver a total of 15 to 20cc of contrast medium. Renografin 76e is preferred over other products used. Slight thumb pressure over the vein distal to the catheter prevents ballooning prior to valve opening. The foot is unloaded while injecting the second syringe to assure lamellar perfusion which is compromised when the foot is loaded.A lateral, an A-P and 65 degree D-P views are taken with all cases. To avoid image distortion perpendicular beam and film projection is used for all views.The preferred x-ray equipment is a portable MinXray 80+f and 3M 2/6 screens with Ultra Detail filmg . For optimum contrast image all views within 45 seconds following injection of contrast medium. Complications: Perivascular injection inadvertently occurs if the catheter penetrates the vein more than once. A temporary coolness of the distal limb occurs but with no apparent lasting side effects. Tourniquet failure causes varying degrees of filling and can lead to a false interpretation. Results: Developing the technique and range of normal, ten feet were examined. One Standardbred adult, two Arabian adults, One Thoroughbred adult and one Quarter Horse weanling.The basic contrast image did not vary significantly among this small group. To adequately perfuse the lamellar vessels, the foot is unloaded while injecting the last 10 cc. Further studies of the micro circulation are indicated to better understand the range of normal. Three suspected keratomas were examined, revealing a distinct space occupying lesion. One persistent quarter crack revealed a space occupying lesion that was surgically removed, eliminating further quarter cracks for a period of three years. Five white line disease cases revealed stark loss of contrast on the laminae, adjacent to the lesion. One hundred three laminitic feet were studied that were suffering from mid to high scale damage assessed clinically and radiographically, (500-1000). Several cases had periodic follow-up, comparative studies. A wide range pattern was found, apparently directly influenced by the initial insult and subsequent compartmental syndrome created by displacement of P3. The lamellar vessels, circumflex zone and terminal arch were assessed as normal, poor perfusion or stark loss of contrast. Treating dozens of high scale (750 to 1000) laminitis cases in a similar fashion, the author concluded that those with stark loss of contrast along the lamellar vessels, circumflex area and terminal arch had irreversible circulatory damage and a very grave prognosis. Variables influencing adequate digit perfusion is multifaceted, not well understood and needs further studies. 29 bilateral cases classified as sinkers in the mid scale range were examined, 750-1000. Unilateral venograms were performed on the foot with the most damage assessed, significant new sole and horn growth was observed within two weeks following the venogram where the opposing foot showed very little, if any, new growth over the same period of time. The same feet grew approximately 1/2 to 3/4 inch of horn and sole respectively within six weeks, whereas the opposing foot had significant less growth. All cases were derotated, shod with a four point aluminum rail shoe with Advance Cushion Support h and had a deep flexor tenotomy. Three cases had stark loss of contrast in all three zones and were euthanized, as they remained non responsive, in spite of aggressive therapy. Two specific cases classified with high scale damage (800-1000) stand out to suggest the validity of the venogram as a therapeutic aid and several others in this group revealed a similar response. Case 1: Quarter Horse show filly, had a venogram right front at the time of admittance. This foot continued to show deteriorating signs and appeared to suffer more damage than the left, but responded favorably, growing 1/2 to 3/4 inch of sole in six weeks when the left front showed no growth and sloughed the hoof capsule,revealing dark gray laminae. A venogram revealed stark loss of contrast along the lamellar vessels and circumflex zone, with moderate filling of the terminal arch. Euthanasia was recommended due to overall grim picture. The client requested two days to absorb the shock of losing her mare. The mare was led out to be euthanized, and found to be quite sound, relative to her previous days of being down the majority of the time. The cast was removed, revealing several areas of pink, healthy granulation tissue. Reconsidering the circumstances, treatment resumed. A venogram was performed every three weeks for three consecutive studies. The clinical picture was improved within days following each venogram. The mare became increasingly sounder, and the hoof capsule steadily regrew over the next five months, protecting the sensitive structures. The mare returned to pasture soundness and continues to have a favorable outcome, nine months after being dismissed. Case 2: American Saddlebred gelding with 500 to 700 range damage. Venograms were done on both feet at initial examination, revealing poor perfusion within the lamellar vessels and compromised areas in the circumflex vessels. Nine months later, the right front medial quarter showed increased sensitivity, the horse was lame, grade 2/5 and the coronary band bulged out over the horn wall. A venogram revealed a loss of contrast in this area. Both feet were reset with a four point aluminum rail with Advance Cushion Support following derotation. Six week follow-up, the horse was quite sound, 1/2 inch of new growth was seen at the coronary band, and a comparative venogram revealed good perfusion of the compromised areas.The following six week period there was approximately one inch of new horn along the medial quarter and the horse was given two additional months turn out and put back into training. Case 3: Thoroughbred race filly with bilateral acute laminitis. A previous bout of laminitis one year ago had caused significant permanent damage in the left front foot, which showed significant radiographic damage and was more painful than the right at the time of onset. The left front was examined by venogram, revealing a pattern consistent with a chronic lamellar scar and reasonably good perfusion in the other zones. She was shod using the above described technique. Six weeks later the left front showed a favorable clinical response, right front, very little if any noticeable new horn growth and exhibited grade 2/5 lameness. Both feet were examined approximately eight weeks from onset via a venogram, followed by shoeing and bilateral deep flexor tenotomy. Within two weeks following the venogram and surgery there was a noticeable horn growth and reduced sensitivity along the medial coronary band right front. The left front continued to show a more favorable response over the following six months. This case continues to be in the recovery stage of the syndrome. Discussion: It was noted that the lamellar vessels had poor to stark loss of contrast when the foot was fully loaded while injecting the contrast medium. This finding, coupled with clinical observation leads to the hypothesis that counter limb laminitis is triggered by inadequate lamellar perfusion. The clinical case that is content to stand for long periods of time without shifting weight to the injured limb is more likely to develop laminitis within three to six weeks from injury than the case with protected laminae that constantly shifts weight or moves about the stall, in spite of being grade 4/5 lame. A Venogram of the digit reveals arterial and venous perfusion, to include micro circulation. It provides a means to visually assess numerous pathological conditions that alter the circulation of the digit and is potentially a helpful diagnostic, as well as prognostic tool. Severely compromised digits suffering from laminitis can show a favorable clinical response following this technique. Further studies are needed to determine the mode of action, and how the response is related to this procedure. References & Footnote: 1Hertsch, Professor Dr. B., Klinik Fur Pferde der FU Berlin, Germany-personal communication. 2 Pollitt, D.V.M., Chris, University of Queensland, Saint Lucia, 4072, Australia personal communication. 3Redden, D.V.M., R.F., 1997 AAEP, Shoeing the Laminitic Horse, Vol. 43, page 356. 4 Pollitt, D.V.M., Chris, An Intimate Look at the Circulation of the Foot, 1992 Bluegrass Laminitis Symposium & AAEP. aDormosedan, Pfizer Animal Health, Pfizer Inc, West Chester, Pa. 19380 b Carbocaine,Pharmacia & Upjohn Company, Kalamazoo Michigan 49001 c Elastikon, Johnson & Johnson, Arlington, Texas 76004-3130 800-255-2500 d Butterfly 21 x 3/4 12 inch tubing infusion set, Abbott Laboratories, North Chicago, Il 60064 e Renografin 76, E.R. Squibb & Sons, Inc., Princeton, NJ for Solvay, Animal Health, Inc, Mendota Heights, Mn 55120 fMinXray, Inc., 3611 Commercial Avenue, Northbrook, Il 60062-1822 800-221-2245 g3M Animal Care, 3M Center Bldg. 275-3E-03, St. Paul, Mn 55144-1000 800-635-5677 h Advance Cushion Support, Nanric Inc, 131 S Main St., Lawrenceburg, Ky 40342

2003 - 16th Annual Bluegrass Laminitis Symposium Notes Written and presented January 2003 by R.F. (Ric) Redden, DVM Laminitis remains one of the horse industry’s biggest killers. Insurance companies recognize colic just ahead of laminitis, therefore it is a very important subject. Unfortunately there are no consistent guidelines to help clinicians and farriers successfully deal with laminitis. In my book, Understanding Laminitis, I have a very simple scale that helps group the cases according to degrees of damage to the vascular supply, soft tissue and bone. The scale in reality is quite complex requiring in-depth knowledge of the subject and good clinical experience. Most veterinarians and farriers see less than six cases a year and may never see a high-scale case. The low to low mid-scale cases fortunately make up the majority of cases across the board. These cases are responsive to a multitude of mechanical devices that include shoes, trim techniques and often professional neglect (simply doing nothing). Mother Nature often smiles on these cases and most recover with little or no life threatening damage. The lower scale cases offer a false sense of security to those responsible for treatment and when no effort is made to clearly define the degree of damage, disaster strikes when the higher scale cases are treated in the same manner. Let's take a quick look at a high scale case. A typical history of the cases I see during foaling season; mare foals, very difficult dystocia. The foal is usually very large, has to be pulled or possibly requires fetatomy to deliver. Heavily stressed, the mare has acute laminitis within hours of delivery. Most cases very painful, grade 5/5, glued to the ground in front and treading water with the hind feet which spells big trouble with this history. Placing her in Modified Ultimates or in Styrofoam doesn't alter her clinical picture as one normally finds with the lower scale cases. The mare continues to fall apart as the day proceeds, heavy breathing, very anxious eye, unwilling to move, eat or drink. Coronary bands are changing rapidly; a very distinct ledge can be felt around the entire coronary crown. Taking radiographs can be a task due to the pain response, blocking the feet just for the sake of taking film is not recommended as more damage quickly ensues when the feet are blocked. Without prior base lines the first set of film may be difficult to accurately interpret. Large Thoroughbred broodmares with some age will often have 20-22mm HL (horn - lamellar) zones and frequently are found with chronic capsular rotation, especially those with poor quality feet. Flat or dropped soles, full thickness toe cracks, typical dish are common findings on some of the world’'s best mares. Nevertheless the radiographic damage may be seen only as lamellar swelling which can be up to 25mm or not demonstrable at this stage. I have seen a handful of cases that went through the massive lamellar slough so quickly that little or no swelling was seen radiographically, they are rare cases. Most cases will show very distinct thickening of the laminae within hours of a significant bout of laminitis. Very disciplined, methodical, repeatable, soft tissue films are necessary to see these early changes. Rotation remains a popular radiographic sign but be keenly attuned to what is happening at the HL (horn - lamellar) zone as it is by far the most useful information. Films made only a few hours later can clearly show an increase in horn - lamellar zone, decrease in sole depth and an increase in C.E. (coronary band - extensor process). Palmar angles may be unchanged. All these subtle but measurable signs indicate massive lamellar dysfunction has occurred and the boney column is descending. Heavy, strong hoof capsules with 25mm of sole certainly have a better reserve than the previously described case, but this case can be very deceptive as rotation may not be seen at all. A venogram is the only way that I can accurately assess the degree of damage at this or any other stage for that matter. The procedure is quite easy, requires very little equipment, but is a timely exercise that must flow along quickly in order to produce quality film. All film must be made within 45 seconds following injection of the dye. I strongly advise everyone to practice the technique on normal horses before attempting a severe laminitic case. Film interpretation must be relative to what is normal. A large range of normal exists as well as a large range of pathology. Making life or death decisions based on little or no experience is high risk and often spells disaster. I cannot stress enough the importance of technique and interpretation. The venogram on most of the mares above will have stark loss of contrast along the anterior face of PIII, stark loss along the circumflex zone and often little or no contrast in the terminal arch. The coronary plexus will appear as a crown well above the hoof, the heel area is most often well perfused. Caution: Tourniquet failure is one of the biggest problems I see with many of the venograms I read. The typical under perfused pattern may appear as described above, but the vessels in the heel region appear as an upside down tree, the vessels taper to finer points much like tree limbs. Avoid misinterpreting the artifacts found with poor technique as it may decide the fate of your patient. When the venogram describes a foot that is basically depleted of the vital blood supply, the primary emergency goal is to restore adequate blood supply to the digit before irreversible damage has occurred. I have used my partial decompression technique to include lower wall resection, upper wall resection and internal decompression technique (deep flexor tenotomy) followed by realigning the palmar surface of PIII, all with a reasonable degree of success. Looking back over literally hundreds of cases, some that pulled through, many that made it but were left crippled and others that simply slipped away from me regardless of my efforts has been humbling. I have often asked myself, what were the determining factors that seperated these cases? Venograms during all stages of the syndrome on a large number of cases has convinced me it was the degree of vascular damage,the speed that it occurred and the time lapse or chronicity of the comressive forces. Full Wall Ablation: The fall of 2000 I removed the entire hoof capsule from a nice filly that was draining sersosanguineous fluid from the top of the right front coronary band. I placed her in a transcortical cast to protect the healing digit offering her immediate clinical relief and bought her enough time to cornify the laminae and grow 10-15mm of sole before the pins were removed. She grew a very nice horn capsule, sole and frog and was very happy for several months, but unfortunately the coffin bone had large areas of irreversible vascular damage and the new horn was formed around the partially dead bone with a pseudo laminae attachment. The persistent decaying effect on the bone and less than favorable horn attachment finally resulted in the decision to euthanize this very nice prospective broodmare. Seeing this opportunity to help others I realized the technique had promise but I had to move much quicker in order to minimize permanent damage to the coffin bone. Since this case I have removed the entire hoof capsule on 13 feet, 8 horses; 1 case euthanized due to lack of a favorable response. 1 case responded well and appeared to be on the mend. It developed a septic coffin joint and was euthanized. 1 case responded well and cornified the laminae in spite of off-the-scale vascular damage. It developed renal failure and was euthanized. The other cases continue to show steady, but slow, improvement. Technique: The transcortical cast can be applied under general anesthesia or standing using a sling and a local anesthesia. I have performed the procedure using both techniques, the downside of general anesthesia is removing the hoof capsule as it is very difficult to peel off when there is no weight on the limb to stabalize the foot. Drilling and tapping the cannon bone and placement of the pins is much easier though on the recumbent horse. Recovery can be tough on the bone around the pins as well as the digit. The standing horse bypasses this risk. The surgical time can also be very short with the standing case, typically 30 to 45 minutes per leg, requires one person on the head and one assistant. I don't advocate the standing approach for anyone that is not comfortable with sudden outbursts of horses that are not broken to the sling. It can be quite harmful for your health as well as others in the immediate vicinity. Standing Technique: I use a high ring block just beneath the knee and allow 30 minutes to totally desensitize the limb. I put a snug Vetrap snuggly over the blocked area to prevent unwarranted edema while waiting for the block to take effect. The lower limb is clipped and prepped once the animal is well sedated and standing quietly in the sling with just slight sling lift placed on the abdomen. Using a Dewalt, 12 volt drill with sterile sleeve and 6.2mm bit, I place two holes through the cannon bone approximately 1-1.5 inches apart. The best location for the holes is where the cannon bone flares outwardly at the fetlock and the other just above. Using a 1/4 inch tap (Imex) and the drill running very slowly I tap both holes. The positive threaded pin is also run in with the drill very slowly. Use a large amount of saline on all drilling and taping tools as thermal bone damage is a big concern. Cut the Pin off with one inch exposed on either side, a good pair of bolt cutters is needed. A sterile bandage is placed over the pins during hoof removal. Raise the horse slightly in the sling, hind feet remain on the floor. Using your nippers remove the sole wall junction all the way around, being careful not to injure the laminae or bone. A pair of half round nippers is then used to get a firm grip on the wall at the heel. Slowly peel the wall, the goal is to peel it in one piece, go slow and allow time for the papilla at the coronary groove to turn loose. Often I will put on a loose fitting tourniquet for this step for those casess that have small areas of perfusion. Most will have quite dark laminae and do not bleed as you would suspect. Once the wall is removed I gently massage the dark laminae until it feels warm and fresh hemorrhage can be seen throughout the entire area. Place a piece of Betadine soaked 1/2 inch felt over the laminae (the shape should mimic the wall you removed). Tape it in place with firm pressure. Place two pieces of Betadine soaked felt on the bottom, apply two rolls of Gortex cast padding over the foot and limb. A piece of 1/2 inch felt at the top of the cast prevents pressure and rub sores. I position the foot in a normal loaded position and apply a cast using five rolls of five inch Dynacast. Often I will use the sling to help control the stance of the animal and position of the limb during casting. When necessary you can lift the horse completely off the ground for a few minutes of pure sling tranquilization, be careful though they blow after five to ten minutes -don't push your luck. Placing a cup shaped piece of aluminum on the bottomreduces twisting pressure on the pins when the horse turns. All cases have show immediate clinical relief, all cases have cornified the laminae within the first three weeks. Pins are normally pulled three to seven weeks once micro fractures appear radiographically. Another cast is applied for three to four weeks. They are not as happy with the pins out and are expected to be down more over the next two to three weeks, therefore bed very heavily. After six to eight weeks I may decide to cut the deep flexor tendon depending on the palmar angles; most have a tenotomy at this stage. Most cases have already had a tenotomy at this stage. Results: Five to six months is required for the majority of the primary horn tubules to grow from coronary band to the sole surface. The sole and frog regenerate very quickly, all have had some degree of bone damage but all those surving continue to show a steady response, they have good body condition and attitude. It is far too early to know how the long range future looks for these cases but it is very obvious that timely decompression of high scale cases is a viable option, especially when all cases were facing euthanasia as the only other option. Call me, I will help you evaluate and move into this exciting treatment option for those with seemingly impossible odds.

Dr. Redden's Notes Ensuring High-Quality Radiographs of the Equine Foot Written by R.F. (Ric) Redden, DVM Radiographic examination of the equine foot can provide a wealth of information when performed in a methodical manner. There is no single protocol that is suitable for every case, but the same basic approach applies to every radiographic examination. Preparation The foot should be thoroughly cleaned of all debris, including any material that may have lodged in the sulci of the frog. The shoe may need to be removed for a complete digital study; however, it can be left in place for lateral, dorsopalmar (DP), and 65-degree DP views. In fact, leaving the shoe on can provide useful information. Also, in very lame horses leaving the shoe on minimizes pain and saves time and expense. The surface of the dorsal hoof wall should be delineated from the top of the wall to the toe using a radiopaque material, such as contrast paste. To facilitate uniform views, the horse's feet should be placed on wooden blocks (one block under each foot). Equipment and Exposure Factors Obtaining consistent, high-quality radiographs requires familiarity with the radiographic equipment. It is well worth taking the time to formulate a detailed technique chart for the x-ray machine, film-screen combination, and processing method you routinely use. Two exposures should be taken for each view. The author uses the following terminology for exposure factors: "soft" (for nonbony tissues), "medium" (for bone of moderate density), and "hard" (for dense bone). Specific exposure factors will vary with the equipment used. Soft tissue detail is essential on at least one film per view, as the nonbony tissues surrounding the distal phalanx are an integral part of all foot problems. However, it is important to establish a range of normal for different breeds and age groups. Routine Views Accurate positioning is as important as the exposure factors used. For the lateral view, the x-ray beam is aimed 1–2 cm above the bearing surface (i.e. at the level of the apex of the distal phalanx), midway between heel and toe. The beam must be horizontal and perpendicular to the sagittal plane of the foot. The two exposures recommended for this view are soft and medium. For a lateral view of the navicular bone, the beam is centered approx. 5 cm (2 in) higher and further toward the heel (i.e. over the navicular bone). The two exposures recommended are medium and hard (using a 6:1 parallel grid). For the DP view, the horizontal beam is centered at the toe, again at the level of the apex of the distal phalanx. The two exposures recommended are soft and medium. The same exposure factors can be used for the 65-degree DP. For evaluation of the navicular bone on this view, the beam is centered over the navicular bone and a hard exposure is taken using a grid. To prevent distortion of the distal phalanx on any of these views, it is important to ensure that the cassette is in contact with the foot and the beam is perpendicular to the cassette.

Bluegrass Laminitis Symposium Notes How Lacerum™ Has Improved the Progress of High Scale Foot Damage Written and presented January 2004 by R.F. (Ric) Redden, DVM Lacerum™ is an innovative product designed and developed by BelumedX out of Hot Springs, Arkansas. I introduced this product approximately one year ago as a means to aid in the treatment of severe foot injuries and disease. Being innovative and willing to explore the unknown, I adopted this product on a trial basis. This paper will reflect some of my clinical findings. The first case involves a quarter horse filly, two year old. She presented to me with left rear foot lameness due to a penetrating puncture wound to the solar foot. It appeared that she had stepped on a steel fence post that had broken off in the ground and fractured her coffin bone. It appeared the center of impact was off the center of her frog. The penetrating piece of steel caused multiple fractures of PIII. She was three-legged lame and had permanent drainage from the bottom of her foot. Euthanasia was the recommended course of action as this seemed to be a fruitless case. I took the case simply because I have had considerable luck treating severe puncture wounds in the past. I applied my typical raised heel, adjustable bar shoe with a toe and hospital plate. This shoe is designed to kick the deep digital flexor out 80-90 percent, allowing the horse to be weight bearing even with the worst puncture wounds. I debrided all the necrotic tissue, and the fracture lines were evident throughout the entire PIII. However, none of the pieces of bone appeared to be sequestrum at the time. The filly was shod on the right side with a Modified Ultimate to prevent contralimb laminitis. This shoe, used early in the syndrome, has worked well for me in protecting the good foot from contralimb overloading, which depletes the blood supply to the anterior laminae. Consequently, this causes laminitis. The filly became quite comfortable following surgical clean up and application of the shoe. I treated her off and on over the next few weeks in a very conservative fashion, to simply provide medical support. She was on a Gentocin and penicillin combination, as well as Bute. Over the next few weeks it became evident that a large fragment of bone that articulated with the majority of the surface of PII had sequestrum and had to be removed. The bone was quite loose through the hole in the bottom of the foot, and it had turned gray to brown in color. This indicates avascular shut down. I teased the piece of bone out, I exposed the majority of the articular surface of PII, and I was pleased to find that the adjacent tissue and bone had a nice, bright pink color with early signs of granulation. I packed the hole with betadine and gauze and proceeded to treat the filly on a bi-weekly basis. My intent was to get this large area, about the size of a hen egg, to granulate and fill in with a fibrotic mass of tissue that would be a specialized, cushion type tissue. This would hopefully give this filly the means to have a quality life. The owner had a sentimental attachment to the filly, and we wanted to do everything possible to save her life. In spite of my effort to encourage granulation tissue to fill this void, the response was very slow to nil. It would fill in over the course of two days to a week with a gelatinous mass, but it never had the strength to go ahead and become a firm, bridging membrane over the end of PII. The opening on the bottom had been reduced from approx. 3.5cm wide to about 1cm wide, which gave a false impression that this area was healing well. However, it was easy to break through and find a large cavity underneath. Having the opportunity to use the Lacerum™, I filled the entire cavity with one dose of Lacerum™ following a flushing with Remex, and sealed the bottom with a hydrogel gauze. I placed the hospital plate over that and hoped for the best. I did this on Tuesday and removed the hospital plate on Friday. I examined the results and was surprised to find that the entire area had filled in with a dense fibrotic tissue. I was unable to penetrate this tissue even with forced pressure with a q-tip. The following Tuesday, this area was very firm and the granulating surface was reduced from 2.5cm to about .5cm. It took about another month to close completely. The cornification occurred in a very rapid fashion, leaving the smallest defect in the sole. This indicated where we had a difficult three months of treating this foot. The filly went on to become quite sound. The foot is quite small, but she is being managed with therapeutic shoeing. There is hope that she will live a quality life and become a successful brood mare. We used the Lacerum™ on several different cases where we had necrotic tissue that was causing us problems. We had mixed feeling on when to use it, how to use it and what to expect. One of my next very meaningful cases was a thoroughbred sale yearling that came to me with a deep puncture wound through the sole of her foot, along the medial sulcus of her frog. The client was devastated because this was one of his big time fillies, and she was the “mortgage burner” of the farm. The injury occurred approximately two months prior to sale time. I spoke with Dr. Dave Jolly and asked what the effect would be if I lavaged the tract and put the Lacerum™ in the hole, instead of doing the routine roto-rooter clean up. If we cleaned it up in a routine fashion, the filly would definitely miss the sale and would be questionable for the training sale in April. This was not the news the owner wanted to hear, so I elected to lavage the very extensive area. The puncture began at the medial sulcus, bypassing the navicular bursa and tendon by micro-millimeters, and liked only .5cm of protruding from the pastern. The area was infiltrated with the Lacerum™ growth factor. The bottom was sealed, which was a very different approach. I usually establish ventral drainage for puncture wounds and have had reasonably good luck doing so. However, we sealed the hole to ensure the growth factor stayed in the traumatic canal. The filly was placed on Gentocin and penicillin. She was never very lame, but she was tender on the foot and had quite a bit of edema throughout the tendon and fetlock. The edema dissipated very quickly. The filly was fitted with a Modified Ultimate so we could reduce tendon pull across this area. We actually put an Ultimate on both front feet to protect from overloading and a laminitic episode of any degree. I was very pleased with the immediate results, as she became quite comfortable. The plug was pulled two days later, and we lavaged the area with saline. We had a bit of drainage, so we packed the area again using an animal feeding tube to ensure I inserted Lacerum™ to the distal extent of the puncture site. We also found another small tract that went off to one corner. It had slight exudate in it, and it opened through the bulb of the heel. I was able to flush it with Lacerum™ from the exterior, communicating with the original puncture site. This foot was treated with four Lacerum™ applications over a period of three weeks. At this time the hole had sealed at the bottom, and it was only slightly noticeable with an astute eye. We kept the filly 30-45 days and sent her to the farm wearing a protective shoe so she could prepare for the sale. The filly went to the sale quite sound. She was shod in a normal fashion, and she sold quite well. She was a bit behind in conditioning, which was to be expected considering she was stall bound for six weeks. She has continued with training and being broken, and she should have no ill effects whatsoever. This case really highlights an important point. If we can use a growth factor to accelerate the normal healing response with foot problems, then we can bypass the normal secondary sepsis that is often devastating to a lot of foot injuries. The third case involved a broodmare I worked on 4-5 years ago. She had a severe puncture wound, and we were able to save her life. Her PII and PIII, along with the navicular bone, had become one fused mass of bone. She had been quite comfortable and useable as broodmare. She had developed a contralimb overload situation that was a focal, half-foot, laminitic case where she had traumatized the laminae. She also had an ongoing abscess that had totally destroyed the lamellar tissue along the lateral side of her foot. She presented to us with her coronary band blown out from the heel to the centerline, with exudate and the coronary band swollen over the wall. I told the owner the only chance I had of saving her life was to remove the majority of her hoof wall and hope to find a way to revitalize the dark, unhealthy lamellar tissue. We elected to go for it, but the owner did not want to spend a great deal of money. I removed the wall, and the underlying laminae had a dark, devascularized appearance and was soft and mushy. It wouldn't, however, debride from the coffin bone when given a little pressure. I was encouraged because I felt that we still had a good anchor attachment. It was treated with Lacerum™ initially, and we got a good response. We then applied ACell™, a biological scaffold that was developed for the purpose of having a place for stem cells to actually stimulate the tissue underneath. Using the two products in conjunction, this mare continued to do very well over the next few weeks. When I needed granulation tissue, I used Lacerum™. Once the granulation tissue was filled in, I used the ACell™ to enhance specialized cells to speed the cornification. The slides in this paper clearly show the rapid response this mare had. She became amazingly sound over the first 3-4 weeks of treatment. She is now at home, and we see her on a monthly basis. It appears that this mare will continue to be a serviceable broodmare with an acceptable quality life. These are three basic examples of how Lacerum™ has helped us push the envelope on three different types of cases. It allows us to open a new chapter on treatment regimes. Since January 2003, we have treated approximately 50 different cases with the growth factor, and approximately 20-25 cases with the ACell™. The Lacerum™ is a growth factor, and the ACell™ is a biological scaffold. I have found that they work well in conjunction with each other. I have also found cases where I didn't get the favorable response I expected. With anything new and innovative, there are often limitations. Neither product is a panacea for everything that comes down the road, but I think if you examine the efficacy, and this new concept of treating septic foot and leg injuries, you will find it to be a helpful adjunct to your podiatry unit.

Written and presented April 2012 by R.F. (Ric) Redden, DVM To better understand the club foot syndrome, we must be familiar with the mechanical formula and how it greatly influences the various degrees of hoof capsule distortion and bone remodeling associated with this syndrome. There appears to be a direct relationship between the degree of tension increase or contributive force of the DDF muscle and these two very distinct alterations from the normal healthy foot. This paper will describe that relationship and the soft tissue and coffin bone alterations that are found in the four basic categories of club feet.1 These characteristics are unique for each grade, however several variables can influence the stereotype mechanical model. The Healthy Foot First let's briefly describe a healthy foot on a light boned breed such as a thoroughbred, quarter horse, Arabian and other similar breeds. A healthy foot will have a relatively constant growth pattern heel vs. toe, especially when left barefoot. This uniform toe to heel growth rate is clearly revealed by the relatively even spaces between the growth rings, which routinely occur approximately every 30 days. Shoeing styles, trim and reset timeframes can alter this natural pattern to some degree, but it remains well within a range that can quickly adjust back to its original pattern. The hoof wall has a relatively straight, linear appearance and the toe angle has a very large range depending on bone angle (BA) and palmar angle (PA), which can also vary considerably. The approximate angle found along the growth rings when the toe and heel grow at a different rate will closely mimic the PA on the foot that has not been trimmed for 30-45 days. Figure 1A Left: This horse has very healthy, sound feet despite a grade 1 right front club. Figure 1B Right: The right front growth rings indicate a tendency for a negative PA in the right hind due to the club in front. Figure 1C Left: Radiographs of same horse taken prior to 5 week reset. The left front has 25mm of sole, a 0 PA and a very healthy horn wall. Figure 1D Right: The right front has approximately 22mm of sole, a positive PA and very healthy horn wall. Note difference in bone angles. Both feet are sound and healthy even though strikingly different. Sole depth maintains around 15mm plus with a few millimeters of natural cup. This is the goal on trim day. Strong feet and healthy digital cushion go hand in hand - you won't find one without the other. Domestic horses with strong, intact heel tubules will have a positive PA that will fall into a range of 2 to 5°. Contrary to what we have thought in the past, hind feet of light breeds do not have a larger PA or hoof angle than front feet. Observing many foals as they mature, the large majority have a 0° PA behind, which may explain why their heels can quickly crush and a negative PA develops once put into training. With this very basic description of a healthy foot we can start comparing one foot to another, from horse to horse as well as feet on the same horse. Observing the external characteristics and soft tissue parameters before and after trimming or shoeing helps us better understand the interconnectedness of each component as well as how we can enhance the natural healing mode with shoeing mechanics. Club syndrome influence on the opposite foot The foot opposite a club also appears to be greatly influenced by the club syndrome. The hoof capsule silhouette has several distinguishing characteristics that apparently occur due to a significant laxity of DDF muscle tension, which reduces suspension function. In these feet the pastern sits back well away from the face of the dorsal half of the wall but can remain parallel to the face of the body when digital alignment is present. Imagine pushing the pastern forward just above the heel on the club foot. The tension on the DDFT displaces the pastern on the club and the lack of tension on the opposite foot lets it sag, creating the distinct difference. The growth ring pattern on this low foot is often wider at the toe than the heel, indicating the toe is outgrowing the heel. This ratio steadily increases from one shoeing to the next, as blood flow is exceptionally good to the toe but impaired in the heel due to excessive heel load that results from lack of adequate suspension. Figure 2A: Photo of a hind foot with a negative PA and crushed heel. Note the growth ring pattern, very low heel angle, bull nose and coronary band angle. Figure 2B: Right of the same foot. Note the negative PA and digital alignment imbalance. Heel tubules on the low profile foot have a very low angle as compared to feet with even growth ring patterns. The ground surface contact point may be folded forward to the widest point of the foot. The bars are very thin and also folded inward with the heel tubules. The frog is very prominent and extends well past the ground surface of the heels and most often hangs out the bottom well below the load surface of the heels in shod feet. The digital cushion, which can be estimated by placing your forefinger on the frog and thumb in the cleft of the heel, is also compressed. Comparing its thickness to that of the club, it is very obvious that the cushion is all but maxed out. As load is steadily passed to the growth centers the vascular supply is greatly compromised and heel growth shuts down. This can be demonstrated with comparative venograms. As a rule, the higher the scale the greater the imbalance of toe to heel growth on the low profile foot. This DDFT tension laxity closely resembles the relationship of the pastern to the hoof capsule that occurs following a DDFT tenotomy, a procedure that allows the pastern bones to sag, shifting load to the posterior aspect of the coffin joint/navicular area and associated components of the heel. Figure 3: Left: Estimating depth of heel and digital cushion. Right: Frayed heel tubules are one of the first signs of heel crush. How does this happen? The physics of the syndrome are very simple and quite clear if we focus on the function of the DDFT. The club foot results from increased DDFT tension and suspension function. The opposite foot apparently has the same degree of hypo-function; lack of suspension allows excessive internal heel loading that quickly surpasses the limitations of cushion load and recall. As the cushion fails the tubules fail, and the capsule quickly alters the natural growth patterns. One component does not fail alone but affects adjoining support structures. The hind foot on the same side of the horse as the club foot also has distinct characteristics that clearly distinguish it from the opposite hind foot. Even the hind foot that follows a grade 1 club will have a lower profile hoof angle, lower heel and less than healthy digital cushion depth, much like that of the low heel in front. Why this occurs is unknown at this time, but it is the author's hypothesis that both are closely related and the result of the club syndrome. Radiographic Evaluation A low beam, soft tissue lateral radiograph taken 4-6 weeks post trim or shoeing is very helpful to evaluate the severity of a club foot and determine optimum management options. Radiographs made shortly after trimming or shoeing often fail to clearly describe the significance of the syndrome as the PA, sole depth, digital breakover and HL zone are usually altered with the trimming process. Figure 4: Standing the horse on two blocks with the head held straight and low beam penetration can help assure a more accurate radiographic image. Figure 5: Lateral low beam soft tissue view vs. high beam. Note the lower beam projection reveals one branch of the shoe, which is vital for measuring sole depth and PA. This protocol allows for accurate evaluation of sole depth and other valuable soft tissue parameters. It is also helpful to see the dermal/epidermal (DE) zone on all lateral soft tissue detail film. This zone describes the horn (H) and laminae (L) and as a rule evenly divides the HL zone. If the H zone appears quite narrow closer to the toe, this indicates that the toe was backed up (rasped off) by the farrier. Figure 6: Measuring soft tissue parameters on a foot with a positive PA and negative PA. Radiopaque paste along the face of the foot describes the wall proper, which is not visible on any radiographs without an opaque marker. Contrary to popular belief, digital images do not reveal the outermost layer of the horn wall as this small area is always overexposed. Radiopaque paste also describes growth rings that can provide valuable information. Using a nail, needle or wire only touches the high points and therefore does not reveal the growth rings or the true wall margin. It is important to note that a common practice is to trim and shape a club foot to make it appear more normal. This practice can drastically alter several key soft tissue parameters, including the horn-lamellar (HL) zone, sole depth and PA, which can cause confusion when evaluating a foot and lead to misinterpretation. The best time to observe the foot's natural characteristics is 4-6 weeks post trim or shoeing. When interpreting film made shortly after shoeing we must focus on the joint space (lateral view), which in most cases will be very tight along the dorsal aspect and wider along the distal articular zone. This is an indication of increased DDFT tension. Even though PA may be 2 to5° and appear quite healthy, an 8-10° PA will allow for a more even joint space. This is also an indication that increased tension is present due to lowering of the heel, which is a very common practice. The face of the bone of a club foot develops a distinct bulge. The bone shape can also allude to the club foot syndrome even when the foot is freshly shod. In young horses, the distal HL zone is narrower than the proximal measurement. Foals In newborn foals, the coffin bone is quite small and has a very distinct shape and the bone and foot grow rapidly in a relatively natural growth plane. Apparently the overall shape of the bone is greatly influenced by the forces exerted by the DDFT, laminae and ground load, all of which directly influence the nutrient supply to the bone and associated components. Radiographs of foals only a few days old suggest that bone angles certainly do not always match, nor does the overall stereotype shape of the bones match. Feet with higher bone angles are prone to grade 2 or higher clubs, however those with relatively matching bone angles can progress to various grades of club that are noticeable within weeks or months of birth. This syndrome has been previously referred to as an acquired syndrome, however the author is very satisfied that there is enough clinical evidence to support the theory that the club syndrome is congenital with very strong genetic influence. Figure 7: 3 week old foal with a 60° bone angle (BA). Note bone angle shape and digital alignment. As the foal grows and attains body weight the forces at play are certainly magnified. When all forces remain within their natural range, a healthy, sound foot as described earlier evolves. Foals with low grade clubs can escalate to a higher grade, whether due to genetic influence or to increased tension placed on the DDFT by excessive heel lowering. The genetic component seems to have potent influence on the mechanical model of the foot just as it does for other unique characteristics of the individual. When low grade clubs are trimmed or shod in a fashion that increases DDFT tension, they often escalate to a higher grade on the scale due to neuromuscular reflex that is apparently triggered by pain response in the toe area. Simply put, trying to solve the problem of excessive heel growth using the excessive forces that created the problem is often futile and precipitates the common ill effects of the club foot that have been recognized for years. Toe bruising, fragmented terminal laminae, thin soles, lack of toe horn growth and frequently subsequent toe abscesses commonly occur when treatment is designed to eliminate the unique capsular characteristics of the club. Soundness issues frequently plague athletic horses even with lower grade clubs. Figure 8: Foal with a grade 4 club, fragmenting toe, thin sole and no toe growth. This frequently leads to abscesses and ongoing soundness issues. Toe abscesses are very common in foals with grade 2 or higher club feet, but can be prevented by monitoring sole and wall junction integrity. Note a seemingly harmless abscess that often breaks at the coronary band can be a precursor to white line disease in the mature foot. The Mechanics of the Club Foot Removing the heel from a low grade club with a PA that is 5° greater than the opposite foot may appear to immediately correct the club syndrome. However, the heel grows back in 10-15 days. Why does it regenerate so quickly? This brings us to a very decisive point of understanding mechanics. If the heel were growing and pushing the horse upward, simply removing the heel would be a reliable solution. And if this were the case, the freshly trimmed heel would set firmly on the ground once the excess heel was removed. However, even with lower grade clubs this practice can create a remarkable air gap along the ground surface of the foot from heel to toe. Even when it looks to be loaded, one can often slide a business card under the heel almost through to the toe. This foot is now being loaded over a very small part of the toe as the heel is suspended and unable to share digital load. Though an inferior check desmotomy is accepted worldwide as a recommended treatment for mid-grade club feet, the theory that the DDFT is the source of the forces that cause the syndrome seems to get lost. Literature continues to teach that regular, proper farrier care is needed to prevent the heel from growing. Unfortunately this concept violates the mechanical principles of the club foot and can set off a cascading series of events that have the potential to haunt the horse throughout its career. The trigger mechanism of the club syndrome is not known, but it is obvious that whatever it is has a large scale of intensity. Clinical evidence from venograms support the theory that increased suspension forces of the DDFT directly contribute to increased tension and shear on the very elastic laminae and compressive forces of the palmar rim on the sole corium, an easily compressed source of nutrient supply. This domino effect remarkably reduces sole proliferation and sole and toe horn growth. Increased DDFT forces rotate the coffin bone around the articular surface of PII, increasing the PA and internal load on the apex and sole corium as well as additional stress on the distal lamellar attachment and the dorsal face of PIII. As force increases, load on the digital cushion, heel and frog (which are all located below the suspension structures) decreases, resulting in tight, narrow heels; small recessed frog; excessive heel height, etc. These are all typical distinguishing characteristics seen with various grade clubs. Figure 9: Balance = harmony between suspension and support structures. Growth rings become remarkably wider at the heel than the toe, clearly demonstrating the imbalance of forces between the DDFT and its opposing antagonist component, the laminae. The laminae directly oppose the force of the DDFT. The wall then receives load from the laminae, which is passed to the toe at ground contact. Therefore the length of digital breakover demands great respect when attempting to relieve DDFT tension. To better understand the potent effects of the DDFT tension, we need only to greatly reduce the forces at play and observe the medical benefits seen as accelerated sole growth, return of healthy papillae (as seen on the venogram), reduced heel growth and increased toe growth. This treatment concept is referred to as reversal therapy. However, positive results require a few weeks as the foot begins to overcome the ill effects of imbalanced DDFT tension. Unfortunately, much of the horse world continues to want immediate results and simply cannot visualize the DDFT as being the seat of hoof and bone distortion. Grading Club Feet Redden defined 4 basic categories of club feet based on increasing severity of hoof capsule distortion from grade 1 at the lowest to grade 4 at the highest.1 Radiographic evidence can also be correlated to the various categories. As a rule, the higher the grading scale, the greater the degree of capsule distortion and soft tissue parameter alterations. Grade 1 Figure 10: Photo and x-ray of grade 1 club foot. Note the linear alignment between pastern and hoof. This is a very healthy, sound foot. A grade 1 club is often considered to be a healthy, robust foot by most horsemen and professionals. However when we take a closer look at distinct internal as well as external characteristics there is often conclusive evidence that increased suspension force is directly responsible for the subtle but distinct alterations that clearly distinguish it from the opposite foot. In the foal, the most defining characteristics of the grade 1 club with similar bone angle to the opposite foot are is a hoof angle 5°greater than the opposite foot and greater PA relative to the discrepancy in bone angle. The face of the pastern is pushed dorsally in a straight plane with the face of the hoof and the heel bulb will have a fuller appearance, though this is difficult to detect at a very young age as the foot is smaller than the pastern. At 6-12 months of age the grade 1 club is quite easy to identify as the features explained above are simply magnified. The PA will be greater, the frog not as well formed as the opposite frog and the heel and foot width will be slightly narrow. Growth rings will be quite uniform or slightly wider at the heel, especially the lateral heel. A foot that remains a grade 1 club throughout the life of the horse can be easily maintained as long as it is trimmed and/or shod in a fashion that does not drastically reduce PA and thereby increase tension on the DDFT, making it look like the lower profile opposite foot that has a 0° PA and less DDF suspension. The grade 1 club will have a 3 to 5° PA and can maintain 15-20mm of sole on shoeing day. Dropping the PA with every trim to match the opposite foot invariably increases tension on all structures and will slowly remodel the face of PIII, the L zone, sole depth and articular surface. Grade 2 Figure 11: Photo and x-ray of grade 2 club foot. Note wider growth rings at the heel than the toe and the pastern/toe relationship, The 10° PA is evidence of excessive toe loading, In the radiograph, note debris that has invaded the toe. A grade 2 club foot is the most common grade and most often missed, as it can appear to be a healthy foot compared to the opposite grade 2 low heel (slam dunk) foot. Grade 1 and grade 2 clubs have a very similar pastern and dorsal hoof capsule alignment. The pastern is displaced dorsally, creating a linear plane along the pastern and face of the hoof capsule. This characteristic can be detected when foals are quite young. The pastern of the opposite foot sits back away from the linear plane along the dorsal face, creating a slight dip just proximal to the coronary band. The heel shape on the club will have fullness between the bulbs with less of a pocket in the space between the heel bulbs. The lateral view profile of the club heel will be more vertical than the opposite heel. Foals with grade 2 club feet may have a bone angle that is 5-10°greater than the opposite foot. This appears to be unique to the club syndrome as the larger than average bone angle (50 to 51°) has not been documented in the low foot. The apex is always convex in the newborn, but starts to remodel quickly if subjected to excessive internal bending forces. As a yearling the apex will have developed a distinct lip, referred to as a load induced lesion, caused by the unrelenting pressure of the DDF as it presses the apex into the sole corium. Sole depth will be diminished compared to an untrimmed foot that has natural growth. The cup of the foot may be absent radiographically unless the sole has been trimmed by the farrier to remove sole pressure. The face of the coffin bone will begin to develop a slight bulge along the mid face. Distal to this point the bone will have a dish appearance that increases the distance between the opaque DE zone and the face of the bone. This resorption of bone can be confused with rotation of the coffin bone. Note the parallel arrangement of the bone and wall above the bulge. This differentiates the alterations from capsular rotation, which is caused by loss of horn integrity (white line disease, laminitis or both) and occurs along the entire dorsal face. The resorption or remodeling found in the club foot apparently falls under Wolff's law, which states that bone remodels along lines of stress. This lip of remodeling is also accompanied by a higher PA than we find in the healthy foot described above. Figure 12: At first glance this foot might appear to have rotation, but note the parallel arrangement between horn wall and proximal face of coffin bone. Distal to the bulge bone remodeling gives the appearance of rotation. As this foot matures and the forces at play are continually reinforced by traditional heel lowering, the bone continues to remodel along the lines of stress. The lip is resorbed and the palmer surface of the bone is no longer a straight plane. The anterior third of the bone is no longer in line with the wings. This can be considered a load induced lesion and is a typical characteristic of grade 2 club feet. Before trimming, most all grade 2 club feet will have a 5 to 8° PA and can be as high as 10 to 12°. Even if the heel is removed and the PA is subsequently lowered, it will drift back up over 4-6 weeks. This tells us a lot about the foot. If a foot naturally has an 8 to 10° PA but is maintained at 2 to 3° we know without a doubt that the tension on the DDFT is greatly increased on a regular basis. Every time the heel is taken off load is transferred to the toe. Sole depth revealed by radiographs may appear to be adequate, however if this foot was shod 6 weeks previously and only 10 to 12mm of sole is present, the foot is not happy. If the foot has 10 to 12mm of sole and had only ben shod a few days, interpretation would be totally different. When a cup is present, consider whether it is natural or manmade. If the foot was shod a few days prior to the x-ray, we can assume it is manmade and have no clue what it was before shoeing. Here lies the value of noting the last trim or shoe date. Figure 13: This foot has very thin sole and fragmented walls despite being reset several weeks ago, indicating the mechanics are not complimenting circulation to the growth centers. The average grade 2 club often presents to the author 4-6 weeks post shoeing with a history of off and on lameness grade 1-2 out of 5, especially on hard or firm surface. Growth is very limited with the exception of the heels. Several sets of nail holes may be present very close together. The walls have become more fragmented and it is obvious the farrier is running out of horn for a good nail as the growth supply isn't replacing the old nail holes. Grade 3 Figure 14: Photo and x-ray of grade 3 club foot shod with a positive pressure frog plate and rocker rail to self-maintain the exceptionally high PA, all the while drastically reducing DDFT tension. The foal with a grade 3 club foot is normally born with DDFT contraction syndrome, with one foot contracted more than the other. Some may even have contraction through the fetlock and/or carpus. Several treatment options can successfully manage the congenital contraction stage in a large majority of cases, however in some cases the heel remains suspended regardless of the treatment and favorable results on the carpus and fetlock. These feet will likely develop into grade 3 or possibly a grade 4 club feet as they mature. The overall hoof and heel shape will be much narrower on grade 3 club feet compared to the opposite foot. The frog often sits deep within the foot. Internally the PA can be as much as 8 to 10° degrees with the hoof and 20 to 30° with the ground before trimming. Bone angle can be considerably greater on grade 3 clubs; it is not unusual to find a 60° BA on these feet. To determine whether the club syndrome creates the higher BA or the other way around, coffin bone development in a large population of cases needs to be documented. The apex will develop a lip within weeks from birth, especially if efforts are made to reduce heel growth, as this automatically increases apex bending forces. The hoof capsule starts to dish due to the same forces and the more often heel is removed, the greater the dish. Farriers routinely remove the dish once it forms, but it soon returns as the foot is now weaker and more vulnerable to internal forces. This is where we must stop and ask why the dish and excessive heel growth is always there even when both are taken off every few weeks. Grade 4 Figure 15: Photo and x-ray of a grade 4 club foot. Note heel length is almost equal to toe length. There is extensive bone remodeling, which is characteristic of most grade 4 club feet. Capsular characteristics of grade 3 and 4 club feet are not present at birth, however the author strongly believes the syndrome is congenital in nature and the higher grades are a reflection of ever increasing DDF muscle contraction syndrome. These grades develop with maturity and consistent, unrelenting tension of the DDFT. A weanling with a grade 4 club will have very notable DDFT contraction with little evidence of toe growth and excessive heel growth. The dorsal hoof wall will form an angle of 80 to 90° with the ground surface of the heel. The bone remodels quickly and shows signs of extensive bone resorption and remodeling, often appearing as a rounded off, very misshapen surface, indicating a large area of apex has been resorbed. The face of the bone takes on a very distinct bulge much like the grade 3. The distal half of the dorsal face will be well resorbed, creating a much wider L zone than even the grade 3 club foot. PA can range from 10 to 20° within the capsule and is often 30 to 40° in the mature foot. This is the grade that everyone identifies as a club foot as the alterations are so distinct and far removed from that of the opposite foot. Many of these feet have already had several abscesses along the toe, breaking at the coronary band. Most mature animals will have a full thickness toe crack that develops along the scar, created by migrating abscesses that break at the coronary band. Treatment: The club foot syndrome essentially cannot be cured. Therefore the goal is to manage the syndrome. This can best be achieved by greatly decreasing DDFT tension. Because the severity of contraction varies greatly, the level of mechanics needed to offset the imbalance between suspension and heel load is relative to needs of the individual foot. Best results are obtained with young foals, especially with lower grades. However it can also be quite helpful in managing mature horses. My management goals are to significantly reduce the forces of the DDFT in an effort to reduce the severity of capsule distortion. I like to see grade 2 cases appear to be grade 1 and grade 3 and 4 cases as grade 2. There are several ways to reduce DDFT tension. Extend heel length. Push the heel back to solid tubules at the longest length possible (the widest point of the frog) in the same plane as the PA, not from the toe as is required for all flat shoeing. Note the landmarks at the frog/skin junction. Visualize a line passing through this point to the apex of the frog. This is the plane of the PA. Reduce breakover. Backing the toe up has been mentioned and can be helpful, but only on a very small scale as the toe can only be backed up a few millimeters before we are inside the wall, as evidenced by the light yellow color of the distal end. However, using a shoe to greatly enhance breakover lets us leave the toe and bring breakover back 2-3 inches or whatever is needed to place it directly under the center of articulation. First, significantly increase heel tubule support length by creating a 0° PA between the wings of the coffin bone and the shoe surface at the heel. Then rocker the shoe, starting at the heel and working the radius forward. This will increase heel load and maintain original static PA with the ground. The mechanics of this shoe lie in the airspace from breakover to the toe. There is little or no tension on the DDFT as there is no opposing ground force from heel to the center of pivot of the shoe. Shorten the distance between the origin and insertion of the muscle tendon unit. A variety of wedges, shoes and trim styles can effectively raise the heel to accomplish this. However the increased PA is not self-adjusting, and even if it meets the goals of decreasing DDFT tension, heel crushing is inevitable. Many variables can influence the effectiveness of this method. A grade 2 club with a 50° bone angle and 8° PA has a 58° hoof angle, which is 8 to 10° greater than the opposite foot, which has a 50° BA and 0° PA. Raising the heel of this foot by 5° increases the hoof angle to 63°, which reduces the tension on the DDFT to some degree. However the positive effects are limited due to the pre-existing high internal PA. Blood supply to the apex remains compromised as load has not shifted to the heel zone. Therefore to optimally shift load away from the apex and to the heel we need to incorporate all three mechanical methods: creating a 0° PA with maximum heel length; greatly reducing breakover by placing the belly of the shoe under the center of articulation and raising PA with the ground to shorten the length between origin and insertion of the DDFT. This establishes the mechanics for a self-adjusting PA. The horse can shorten the musculotendinous unit at will and with ease. Thus these mechanical properties complement each other. When all principles are followed the horse cannot rock back, which is very important. Pushing the heels back to the widest point of the frog and bringing the breakover back (not the wall) the same amount is often sufficient to maintain a low grade club. Both techniques reduce DDFT tension, and used together they can be highly effective to manage grade 1 club feet in foals, weanlings and adults. Many foals with grade 1 club feet can be managed very successfully as they mature with an easy four point trim. Figure 16: Low grade club foot with a four point trim. Note breakover is pushed back almost to the apex of the frog. Heels are pushed back to the widest point of the frog but in a totally different plane. The sole along the trim plane should be perfectly flat - no crown. Higher grades, such as grade 2, require more mechanics (higher PA) to offset the adverse effects of increased DDFT tension because there is more tension involved. Start by backing the heels up to the widest point of the frog (solid tubules) in a plane with the palmar wing using external landmarks. Be conservative and leave as much foot as possible while achieving the desired mechanics. Figure 17: Before and after radiographs of the same foot. Note area of breakover and the fact that 20mm of sole remains after the trim. As you rocker the toe of the foot with the rasp, make sure it is in a flat plane across the sole forward of the location of the apex of PIII and perpendicular to the frog. There is very little sole at this point. Rasp breakover forward of the apex to prevent loss of sole depth under the apex. The author prefers a shoe that has mechanics on the ground surface, e.g. Nanric Rocker Race, Nanric Full Rocker or Nanric Rail shoeA, which are rockered to offer even more mechanics for most all cases. When rockering the shoe, start at the heel, making certain the breakover point of the shoe is closer to the heel than the toe. This will allow you to set the heels to the trimmed heel tubules. There is no reason to bring the shoe back farther than the trimmed tubules at the base of the frog. When the shoe is placed on the foot, the peak of the belly will be at the widest point of foot. Higher grade clubs may require the point of pivot to be slightly forward of the widest point of the foot. Be careful not to just bend the shoe; it should be a gentle, smooth radius from toe to heel, foot side as well as ground side, with no flat places on either surface. Radiographically this will be directly beneath the articular surface of PII. The PA is self-adjusting when the belly of the shoe is right and there is no resistance of the toe against the DDF muscle. Shoes can be glued on foals with Equilox, however caution should be taken to cover any and all small separations in the terminal laminae with wax or composite product to prevent sealing up bacteria that can create potential abscesses. Within 30 days, radiographs should reveal double or often triple sole growth, especially in young foals. Horn growth will likewise have approximately the same growth rate response and PA should hold, meaning it remains at or close to zero with the heel branch of the shoe just as it was when the foot was shod. When PA holds it means the mechanics are adequate to balance the force of the tendon with other support components. When this occurs the vascular supply is mechanically uninhibited, enhancing nutrient supply to the solar papillae and primary horn papillae. As a result growth rings at the coronary band will be equal from heel to toe. Figure 18: Radiographs of a foal with a grade 3 club. Note the increased sole growth after only 5 weeks shod with a Nanric Rocker Race shoe. Most young cases will require 2-3 resets using this concept before they can be weaned out of the shoe and into a 4 point trim that also should maintain optimum sole depth. Remember if the sole is not growing 5-10mm per month the vascular supply is mechanically inhibited. If sole depth diminishes and/or PA increases, go back to the higher mechanics of the rocker shoe. Using the reversal therapy concept to balance heel/toe growth produces exceptionally thick soles and good, strong walls. Relieving internal DDFT tension also preserves the integrity of the apex and palmar rim, which is essential for athletic potential. However the foot will always be narrower than the opposite foot and possess the subtle signs a club foot even if it is managed as a lower grade. We do not cure it, we manage it. Surgery When shoeing mechanics have failed to suppress excessive heel growth and promote sole growth, it is time to consider surgical options. Surgically lengthening the musculotendinous unit can be accomplished several ways. Inferior check desmotomy: This method has been advocated as an efficient means treating club feet for many years. The author's approach to when, how and why to use this method can help overcome several problems that can potentially interfere with a positive outcome. Factors to consider when considering surgery include: Age. Foals 4-8 months of age appear to be most responsive to surgery and as a rule experience less scar formation than yearlings and more mature horses. Severity of contraction. Surgically cutting the check allows approximately 15° of PA decrease. For higher grades, this may not be sufficient. Bone angle. Bone angle, which can be measured from low beam lateral radiographs, should be taken into consideration. The bone angle in a club foot can be several degrees higher than the opposite foot and adds to the overall hoof angle. If the bone angle is 8 to 10° larger than the opposite foot and the PA is only 5°, the best improvement in hoof angle we can achieve by cutting the check is 5°. The bone angle will keep the hoof angle a good 10 to 15° greater than the opposite foot and minimal cosmetic or medical benefits have been achieved. Most grade 2 and low to mid-grade 3 club feet will show a favorable response to an inferior check desmotomy provided all other variables, including foot stereotype, chronicity, degree of internal surgical gap and follow up care are taken into consideration. Shoeing: Preparing the foot for optimum surgical gapping is of utmost importance. Dr. Redden prefers to create a 0° PA and maintain a minimum of 15 to 20mm of foot mass between the palmar rim and shoe. Farriers need to work from radiographs to appreciate the small but essential details as the foot is trimmed and shoe secured to the foot. Shoeing prior to surgery prevents unwarranted bruising of the surgical area. When shod after surgery, the farrier's knees can cause unwarranted pressure, bruising and bandage slip. Often there is not enough heel, not enough sole or both to reduce PA to 0°. In order to do so, draw a line on a lateral radiograph parallel to the palmar rim (along the straight part of the wings) and another 15 to 20mm below the palmar rim. This is the trim line. The goal is to preserve as much foot as possible yet establish a 0° PA, which produces optimum surgical gap. The larger the gap between the ends of the cut tendon, the more favorable and lasting the results. Figure 19: Shoe applied pre-surgery creates 0° PA. Heel raise is made with ACSB to facilitate standing surgery when elected and also to reduce unwarranted soft tissue damage by allowing gradual PA reduction. Performing the surgery: Literature has previously described the procedure as the open method in the proximal cannon or with a bistoury using ultrasound control, both performed under general anesthesia.2 However the surgical site invariably results in remarkable scar tissue whether performed from the lateral or medial side. The author prefers to cut the tail of the check mid-cannon as it is an easy procedure that can be performed on the standing horse using sedation and local anesthesia. A post-surgical compression bandage adequately protects the mid-cannon site, as opposed to a proximal incision surgery site that is barely covered by the bandage, which often slips or is pushed down by the foal, exposing the incision and creating unwarranted swelling and scar. Cutting the tail of the check appears to produce less serum leakage, apparently due to the denser, fibrous nature of the ligament at its insertion. The check ligament insertion with the DDFT varies greatly from horse to horse and can be isolated mid-cannon in most all horses. Weaning the PA down: Suddenly dropping a PA to 0° often elicits a painful response as several other adjacent components are forced into a drastically different plane of load and support, particularly the supporting ligament to the navicular bone. Note the close proximity of the navicular bone to the proximal border of the second phalanx before surgery and the significant distance after surgery. Placing a large 20° custom made rubber wedge (ACSB or similar rubber mix) under the foot prior to surgery greatly reduces tension on the DDFT, which offers easy check isolation from the DDFT, prevents unwarranted ill effects of loading a zero PA before the check is cut and offers an easy letdown protocol that prevents unwarranted pain and damage to soft tissues. Aftercare: Strict stall rest for 30-45 days; hand walking for another 45-60, bandaging changes every 7-10 days for 60-90 days offers best cosmetic results. Reset the shoe in 30-40 days and evaluate PA. It should continue to be 0 to a few degrees positive if the surgical gap was long enough. DDFT Tenotomy: The majority of grade 4 club feet require complete release of DDFT tension, which can be achieved by surgically severing the DDFT. Choosing the surgical site is an important consideration for several reasons. Proximal to the check: Cutting the DDFT proximal to the attachment of the check lengthens the musculotendinous unit slightly farther than cutting the check and can be an effective approach for the high grade 3 and low grade 4 club feet. The procedure can be easily performed in the standing horse using sedation and local anesthesia. As a rule this approach produces minimal scar and reduces PA approximately 15 to 20°, therefore shifting the grade 4 club to a more manageable grade 2 that can better serve the athletic potential of the individual. Mid-cannon: The mid-cannon tenotomy is quite easy to perform standing. Shoeing the foot prior to surgery to create a 0° PA with the shoe produces the best results. The shoe needs slight toe extension to assure the largest tendon gap and heel extension to prevent luxation of the coffin bone and toe lift for the first 30 to 45 days following surgery. Note the shoe is set to the foot using composite such as Equilox parallel to the palmar rim with 20mm of space between the shoe and palmar rim. Leave all the foot mass possible as the heel carries load when the DDFT is severed and needs mass to withstand the increased load. Cutting the deep in lieu of creating a 0° PA can produce disappointing results as the coffin bone remains trapped in the contracted position within the capsule, thereby preventing decompression of the sole corium and apex and the desired load shift to the heel. Mid pastern: This site is at the distal end of the musculotendinous unit and should be reserved for the very last resort if and when the contraction phase exceeds the ability of the more proximal surgical procedures. Once this area has developed the typical post-surgical scar, cutting above has little or no mechanical advantage. There are several pitfalls that can reduce the effectiveness of the surgical approach, such as failure to realign the palmar rim with the shoe surface (0° PA), removing far too much heel in an effort to set the shoe on the entire foot and excessive joint luxation due to lack of adequate heel support. A bistoury seldom if ever cuts through the entire tendon and most often does not cut the check fibers. When the bistoury cuts the taut, main body of the tendon it will pop, form a gap and make you believe it is cut through and through. Make an incision, take a look or feel the tissue that remains intact. This approach can cause extensive swelling and unwarranted post op pain. Young foals 4-8 months of age can have an athletic career barring any and all unforeseen setbacks. Older horses heal slower and require a larger recovery period, and can have quality lives as brood stock and/or perform light work. Using simple mechanics that can be designed with a variety of shoes we can tweak the mechanics to meet the requirements of the foot. Reading the growth rings, sole response and soft tissue parameters we can successfully manage a large number of feet that fall within the grade 2-3 range. Let's forget once and for all about matching toe angles and focus on maintaining toe growth, sole growth and suppressing heel growth. Redden RF. How to Treat Club Feet and Closely Related Deep Flexor Contracture. In Proceedings, 16th Annual Bluegrass Laminitis Symposium, 2003 - Louisville, KY. Waguespack RW, Caldwell F. How to Perform a Modified Standing Deep Digital Flexor Tenotomy at the Level of the Proximal Interphalangeal Joint, in Proceedings, 55th Annual Convention, Am Assoc. of Equine Prac. 230-237. A. Nanric Rocker Race, Nanric Full Rocker, Nanric Rail shoe are manufactured by Nanric, Inc., Lawrenceburg, KY. B. Advance Cushion SupportTM, manufactured by Nanric, Inc., Lawrenceburg, KY.

Indepth Equine Podiatry Symposium Notes Written and presented January 2010 by R.F. (Ric) Redden, DVM