Written February 2023 by R.F. (Ric) Redden, DVM Farrier/Veterinarian Podiatrist *Due to the number of images, this displays best on our mobile app http://www.mobileapp.app/to/GcD_BWw?ref=cl or a PC. How do we understand what we see? We simply must consider the tremendous benefits of detecting and processing the smallest details. The information that passes from eye to brain travels along a pathway. When the path is cluttered with other areas of interest it fogs the image, obscures the details, and we may miss a lot and never realize it. When we are just looking but not observant or inquisitive, we see but it does not transfer into our memory bank. When we look with purpose, it changes the game plan.  The purpose emphasizes what we are looking for. There are several ways to assess a foot: visual, photos, radiographs, venograms and MRI. We look for the unique characteristics that are within the range of norm, or better said, the range of health. Or we look for what is wrong. Either way there is a certain level of knowledge required for us to determine the healthy range as it relates to the external characteristics and internal soft tissue parameters, bone shape, genetic variations, and pathology. I often get the question, "What is a normal palmar angle (PA)?" and it makes me realize the journey ahead of that student has just begun. Let us practice programming what we see with purpose. Visualize angles relative to plumb. Draw a few with a protractor then draw without it. Fig 2. Sketch each prominent feature of this foot and think about the internal arrangement relative to external clues. What we see and what we really understand is two totally different perspectives. Tuning one’s eye to see 3D is the key to unraveling the mechanical formula. Fig 3. Practice sketching in a methodical fashion. Farriers this is a great way to learn the radiographic message. Fig 4. Radiopaque ground marker, paste on the wall, and calibration aid are valuable. Which DP image is flipped? Fig 5. Learn the landmarks. A dot of radiopaque paste on the tip of the frog and another at the skin/frog junction is an identical plane as the palmar rim and a valuable landmark for farriers. Fig 6. Lens angle perpendicular to the subject, 24 to 30 inches away from subject and direct light on your back makes great photos, void of bird’s eye distortion. Use this space to sketch the model. Fig 7. Sketch the bones separately then put them inside the silhouette. Practice, practice, practice. We learn by repetition. Fig 8. Note the PA of this untrimmed foot is very similar to the growth ring pattern and for good reason. Fig 9. Study and sketch each mechanical component. Note the stark differences in the profiles. Fig 10. As you sketch the suspension components visualize the forces at play that interact as antagonists. When one component is injured, structurally weak or displaying excessive strength, how does that effect the balance and harmony of the big picture? Fig 11. Sketch the components and get your head wrapped around the stark difference in DDFT function. Toe angles are only 8 degrees different. Not bad for a mismatched pair. Fig 12. The negative PA has wider growth rings in the toe than the heel. Everyday since the last reset the toe outgrows the heel. This cycle increases with the passing of time. The heel tubules are already folded under the hoof and the papillae are functional, but growth planes are grossly distorted. Toward the end of the reset cycle the toe growth accelerates and the heel continues to crush. A vicious cycle.  Think about the imbalance of forces. Why does this occur? Fig 13. Sketch the unique characteristics. Always think about the cause and effect. Very small variances in distance make up the cumulative characteristics that make all feet strikingly different inside as well as out. Fig 14. This cadaver foot has a Note perpendicular pastern, congenital joint slope distinct coronary band and medial rim listing. This is natural imbalance typical of sinkers. for this foot. Fig 15. Note the linear alignment. The pastern is pushed forward due to the increased DDFT tension in this Grade 2 club foot. Note the dorsal face of P3 profile. That is consistent with even the low grades. Fig 16. The fetlock joint consistently slopes proximal to distal and medial to lateral. The pastern joint as a rule will slope in the opposite plane and the palmar rim may also be in an identical plane. The radiographic joint spaces are affected by stance therefore we should strive to obtain a natural stance when taking the DP or PD views. Images that reveal the pastern perpendicular to the ground offer a relative accurate assessment of static balance. However, conformation variables can prevent us from obtaining this preferred criterion. Emphases in the past has focused on the palmar rim as a balance indicator. However, asymmetry of the P2 and P3 frequently occurs which changes the perspective of which is most important, rim balance or joint spacing?  My podiatry experience has been convincing that static joint balance trumps rim balance and mass trumps balance. Fig 17. The needle reveals the location of the opaque margin that can be visualized on the lateral image relative to the d (DEJ). The DEJ is a valuable landmark for monitoring the slightest laminae alterations that occurs with acute laminitis. The club foot bone profile results in a wider L zone along the distal 1/3 of the dorsal face that can be misinterpreted as capsular rotation. Looking closely at the parallel orientation between the horn and dorsal face of the proximal L zone confirms that distal widening due to bone remodeling should not be defined as capsular rotation as rotation due to laminitis occurs along the entire length of the L zone. Fig 18. Sound, high level horse with This foot is a Gr. 2 plus club Gr. 2 club foot with typical with chronic laminitis. Note remodeling of the distal, the L zone deviates along its dorsal face. entire length. The more information we seek the more we find and greater becomes our arsenal of options. Use the space below to sketch the unique differences in the margins of the two above L zones. Fig 19. As we think about mechanics let’s put a little life into our thoughts. Visualize the boat crank being the deep flexor group. The DDF tendon is a mere extension of the muscle that transfers the force of contraction as well as the laxity or dysfunction of the muscle fibers. Listen to the crank click click as it suspends the wings of P3 raising the PA. Flip the lever and the handle spins counter clockwise lowering the PA. Fig 20. Note that the HL zone is questionable without paste to mark the wall margin and prevents a relatively accurate assessment of the CE zone and does not reveal the growth ring pattern. Fig 21. Examples of negative PA without crushed heels. The rockered Full Rocker Shoe is an easy way to reestablish digital alignment, remain in full training, and minimize heel crush. Fig 22. Growth rings are about 30 days apart. This horse blew an abscess in early April. The photo on the right was taken 7 months later. Fig 23. Note the bone side of the deep flexor and nutrient supply to the coffin bone. Fig 24. The above navicular bones are examples of three different perspective views of the same bones. Lesions on the tendon surface are difficult to put in relief as they often occur in the mid to distal tendon surface. The tunnel block is advocated as a reliable positioning aid. However, when the primary beam strikes the detector at an angle less than or greater than 90 degrees the result is image distortion that increases as the angle deviates further from 90 degrees.

Written April 2022 by R.F. (Ric) Redden, DVM Farrier/Veterinarian Podiatrist Wikipedia says Equine Podiatry is the study or management of the equine foot based on its anatomy and function. That is well said as it places Equine Podiatry into a totally different category than shoeing horses and veterinary medicine. The mere description brings the farrier and veterinarian together as equally respected team members in their quest for success. It is about stepping out of comfort zones and pushing their individual job titles into a field that requires further knowledge, training and experience. Employing external mechanical manipulations (trimming and shoeing) to offset function deficits of internal components demands our greatest respect. The job title “Equine Podiatrist“ is used by a wide range of backgrounds and credentials. Let us break that generic definition down a bit further. What is a remedial farrier?  Basically, it is a farrier that is searching for a remedy or cure for a foot issue that may or may not be based on anatomy and function however they may feel qualified to be called a Podiatrist and in each sense that would not be out of line. To be recognized publicly as a Farrier Podiatrist Specialist they must extend their knowledge, training, and hands on experience well beyond the basic requirements of farrier certification and competence. Veterinarians that wish to be recognized as an Equine Podiatrist also must accept the responsibility of being recognized as a specialist. This requires further education, training and experience examining, treating, and managing foot issues as a team member. Veterinarian podiatrists that have previously obtained competent farrier skills can be referred to as a Veterinarian/Farrier Podiatrist. Those that have little to no farrier experience must rely on a farrier for the mechanical trim, shoe fabrication, and application.  This can be problematic for all concerned when there is not a common thread of education, knowledge of the subject, and experience working as a team member. Unfortunately this is often the case as podiatry knowledge is by and large gained from hands on experience. It is all about form and function.  The external characteristics are dependent on the unique interconnectedness with the internal components and the forces at play. This in turn has a direct relationship on the overall status of the vascular supply that is paramount for the growth, maturation, and maintenance of the vital growth centers. Equine Podiatry is not just about shoeing horses as that is a totally different classification of education, knowledge, skills, and experience. Nor is it just confined to veterinary medicine and a DVM degree. Unfortunately to date formal education, training, and testing in this desperately needed field is not widely available for either farriers or veterinarians, therefore preparation to reach an acceptable level of competence requires years of On-the-Job Training (OJT). By and large a specialist concentrates on a particular subject or activity and they are highly skilled in a specific and restricted field.  As the farrier and veterinarian become more specialized with advanced knowledge and skill development, they may be considered an expert. That means they have comprehensive and authoritative knowledge and skills in podiatry. Comprehensive includes all or nearly all elements or aspects of podiatry mechanics and to be authoritative one must be trusted as being accurate, true, and reliable. Therefore, equine podiatry is fraught with misconceptions, opinions, concepts, and techniques in lieu of an established standard of care. It's potluck and being armed with only good intentions in a field that is vastly different than their respected professional duties has inherent risk of imposing unwarranted pain and suffering on their mutual patient.  OJT can be a meaningful and productive approach to education when the mentor has gained exceptional knowledge and good experience through years of intense cases with many lessons coming from the agony of defeat. However, mentors with decades of exclusive podiatry practice are few and far apart throughout the world. Therefore, farriers and veterinarians must have a dedicated heuristic approach to seek an acceptable level of competence as a podiatry team member. In the meantime, the horse owner relies on their farrier and veterinarian, believing without a doubt that both are highly qualified and experienced with career and life-threatening podiatry issues. It is only prudent that the veterinarians and farrier understand the merits as well as limitations of their team member. This is the difficult part of the puzzle that requires no explanation as it often becomes obvious that intense preparation has normally not been considered by either extremely busy individual. When a common thread of knowledge does not exist between two individuals filling the shoes of a competent team member, it becomes a daunting task.  The very perception of the issue whether career or life-threatening is often as different as the goals of mechanical and medical options.  Yet they are expected to overcome the huge handicaps that are the product of extrapolating expertise from one professional area of expertise to one that demands baseline preparation. Therefore, success is often left to chance and the downside of the gamble is a recipe for devastating results. It's time for a change. When one or other of the team or both have little or no knowledge and even less skills in podiatry, they invariably struggle. Despite the best intentions the very basic principles of podiatry escape them, tremendous efforts become futile, and the horse and owner suffer the consequences. If we want to become more competent in a field that is basically void of formal education, training, and competence testing, we must strive to follow those that have taken this field very seriously and paved the way for others to avoid the many pitfalls that lie ahead. What is the availability of podiatry education and training for veterinarians? Vet schools teach very little if any specific subject matter relative to podiatry. Therefore, national and state exams as a rule avoid podiatry questions as part of the qualifying criteria for licensed veterinarians. The public on the other hand are not aware that the foot of the horse is seldom if ever mentioned during the four year course of study. Most state and national organizations are now aware of the serious black hole that exist in veterinary education, training and expertise and they are reaching out to others that have obtained some level of competence and experience in the field as speakers for conferences, workshops, and virtual education.  Veterinary associations have found that podiatry subjects are quite popular and that farriers are very eager for knowledge and training.  Veterinarian students that entered school as competent farriers can easily pull from their previous knowledge of the foot and have a good idea of what they now must learn to start connecting the dots with podiatry issues.  Veterinary students are finding equine podiatry to be very exciting, and they are willing to invest their time attending farrier schools, working as a farrier assistant or apprentice to gain adequate knowledge and skills to better understand the foot, the trade and the serious preparation and responsibility of podiatry. Years of trimming and shoeing top level horses of many disciplines prior to entering vet school certainly opens many doors to podiatry. Farrier schools as a rule are focused on the very basic principles of trimming and shoeing that entails only a few weeks to months of education training and skill development. Hands on experience (OJT) over the next few years’ experience is then required to reach an acceptable level of competency as a farrier. However, this is only the first step to becoming a farrier podiatrist.  Anatomy and function must then be learned from a medical perspective and requires serious dedication to pursuing knowledge of the subject though lectures, hands-on classes and an evolving mind set for the mechanical thought process. It is paramount that podiatry focused farriers develop radiographic skills and learn to use this information as effectively as possible. Informative radiographs are the common link that can bridge the gap of communication between the attending vet and farrier.  Farriers with years of top-level shoeing are taking up the challenge of becoming veterinarians in their quest to become qualified and more competent podiatrist. This brings us to the question of being prepared as individuals and team member to accept the responsibility of a career and or life-threatening case. I often asked myself many years ago as I looked into the eyes of a horse suffering intense and often excruciating pain “Redden, do you have the credentials and experience to ease their pain and enhance the healing environment?" My four decades of extensive, exclusive equine podiatry practice has been fraught with highs and lows treating life-threatening foot issues. My heuristic approach to navigating through difficult cases paved the way for others to follow my logic and success with issues that once were thought hopeless. It's time for a change.

A Valuable Diagnostic Aid The venogram offers tremendous insight into the status of the vascular pattern. Therefore it becomes a valuable diagnostic aid for the vet/farrier team as they seek optimum mechanical decisions. ​ View Dr. Redden's instructional slideshow below. The PowerPoint and PDF files can also be downloaded.

Written November 2018 by R.F. (Ric) Redden, DVM Toe extensions with a slightly rolled toe work mechanically in two basic ways.  The most beneficial is to prevent the horse from dragging the foot when unable to extend the coffin joint due to a traumatically severed extensor tendon.  The toe simply cannot be extended in absence of the function of the extensor tendon.  This is a very common injury as this tendon lies along the face of the cannon bone and just under the skin leaving it vulnerable to serious injury. The other function is to use it as a lever to force the heel down via the weight of the horse when there is an air space under the heel when fully loaded. This can be a useful tool but demands great respect and a thorough understanding of the circumstances that can prevent the heel from touching the ground in absence of a painful response. Injury to the muscle belly and or deep flexor tendon that can cause temporary shortening of the flexor apparatus. Easy stretching in small increments can offer beneficial results as healing occurs.The club foot is often thought of as a candidate for a toe extension but it can be contraindicated with grades 2 through 4 Redden categorized club feet. (4 basic grades of 1 to 4) (Image courtesy of Sebastian Duran) This diagram reveals the fragile and vulnerable nature of the blood supply in the toe area.  Extending and or lowering the heel on club feet greatly increases the mechanical load on the soft tissue and apex of the coffin bone and that can be counterproductive. Grade 1 being only 5 degrees and a naturally steeper toe angle than the opposite foot. A small toe extension can produce favorable results with a grade 1 provided the sole depth remains adequate, growth rings uniform, and the heel rests on the ground when the foot is placed slightly behind the opposite foot. Grade 2 has more heel growth than toe.  Note the wider heel growth rings.  The palmar angle (PA) will be larger and the bone angle may also be larger than the other foot.  When the excess heel is trimmed off, the heel can no longer touch the ground therefore this age-old concept becomes contraindicated as it is increasing the very force that caused the club. We know with great certainty that the seat of the contraction syndrome lies in the synapsis of the muscle fibers, creating continuous firing of the signal shortening the muscle length and subsequently the muscle tendon unit.  Attempting to counter this force with a toe extension could offer favorable results provided that the hoof capsule, laminae, and solar corium are durable enough to absorb the remarkable increased tension.  Unfortunately, this is not the case as the foot inside and out remodels very quickly due to the increased force applied by the toe extension lever.  The sole gets thinner, the hoof develops a dish simply bending due to the pull of the DDFT, the apex rapidly develops a lip appearance and then starts to resorb as the tension remains constant. Grade 3 has a dish and all the above ill effects and is most often the product of trying to stretch the tendon at the cost of the foot. Removing the dish with a rasp along with the excessive heel adds fuel to the fire and soon the potential for athletic soundness is in jeopardy. Grade 4 the heel is almost as high as the coronary band at the toe, most  proximal dorsal wall is 80 to 90 degrees and the PA can be as high as 30 to 40 degrees.   This is the upper range of the club syndrome.  The mismatched syndrome is apparently a manifestation of the club syndrome ranging from grades 1-4. Points of interest There are common alterations that  occur respective of each grade that can be routinely identified in the high foot, the opposite, and the hind foot that follows the steeper foot in front.  The rocker concept is an option that can accelerate sole grow, increase the dorsal horn grow rate and suppress heel growth especially when employed the first few weeks of life. For those wanting to use toe extensions for foals, think about the forces at play that are responsible for the club foot.  Would it not be better to reduce the tension on the DDFT and  bypass the ill effects of thinning the sole, slowing the growth, creating a dish and increasing heel growth?  One can reduce the tension responsible for the club foot by using the properly applied rocker concept to accelerates sole and toe growth, reduce heel growth and prevent the dish from forming.  The mature horse with a Grade 2 or 3 can respond very nicely with the same concept that is used to manage it in the young horse and remain competitive in the rocker shoe.

2017 Equine Podiatry Notes Written and presented August 2017 by R.F. (Ric) Redden, DVM Our eyes simply transfer images to the threshold of our brain as only a glimpse of what was actually before us. How we transfer that imprint to deeper thoughts and meaningful perception is unique to each of us at any given time. No one can actually view the world through another's eye therefore our perspective and perception will never be identical to that of others.  However, to enhance communication we must strive to bridge this gap and search for realistic ways to train the eye and process what we see in a communicative fashion so that once we can clearly see the forest we can then start to see the trees the limbs leaves and smallest acorn. Understanding what we see is obtained through years of searching the finest details we can possibly imagine using a disciplined, methodical training protocol. Repetitious exercises that are well tuned and designed to consistently eliminate eye error are required for most everything we excel in. How to view feet in order to learn the secret message 1. Start with only 2 planes and focus your primary vision on an imaginary laser passing through the sagittal plane of the foot and the transverse plane at a level that is centered midway between the ground and coronary band. This perspective requires photos taken along these planes as it is not practical or possible to view this plane with the eye. Objects viewed through a lens are identical to what the camera sees not what the person taking the photos think they see. We have all been there and viewed our distorted photos. It is very important that we practice taking these precise repeatable views in order to process this image over and over, so we start to all see the same level of detail even when viewing the foot from others perspective views. Also, be sure to put all direct light behind you to prevent blackout photos. 2. Once we have captured the most represented perspective of the foot we can further our image /brain transfer by putting what we see on paper. My students often say, "I can't draw" my answer that's because you are only looking instead of seeing. Our pen or pencil will follow the command of our brain as it traces the image that we have perceived. This may be a bit awkward for a spell but improves quickly once the real image gets further across the processing threshold that is considerably different than just seeing. 3. Develop a systemic approach to sketching what you see perfecting it as your eye hand coordination improves. To do this we must let our eye see specific areas of the foot in a systematic fashion, e.g. dorsal face, coronary band, ground surface, heel and bulbs and pastern plane and alignment relative to the planes of the foot. Repeat the sequence with every foot you observe from the smallest details from this day forth and soon your eye starts to transfer very small details to your brain that before never crossed that line. 4. Break the foot profile down into smaller zones, starting with half then quarter, 1/8 etc.  Just like a zoom view and study what you see, consider the options, healthy areas, pathological or just different from the last feet studied as well as the text book model. Practice drawing with various sized grid patterns overlays. Feet are just as unique as faces on people or finger prints. Stop and think, do we consider faces pathological or unhealthy simply because they are uniquely different? Of course, not and we must become aware of the healthy unique characteristics of feet and learn to identify the borderline between unhealthy areas and remarkable pathology. Equine podiatry is as much about farrier knowledge and experience as it is veterinary medicine and the responsibility to the overall health and maintenance falls equally to the respective professions. Sounds simple and straight forward however the efficiency of the collaborative efforts is dependent on the mutual level of knowledge and skills of each professional as they collaborate on podiatry issues. Developing an eye for detailed characteristics is the first step in our pursuit to better understand podiatry principals and is essential for collaborating professional to communicate goals, options and monitor response. 5.  External characteristics of greatest interest Hoof profile, the angles and planes that can involve the wall surface from coronary band to the ground contact can change every few centimeters and each alteration is there for a reason and considerably different than text book models. Growth ring patterns toe to heel, medial to lateral describes the history that is a direct influence of the nutrient supply to the tubular and solar papillae. This in turn is directly influenced by the forces within the foot giving meaning to the word mechanics. Genetics plays a major role in the basic stereotype of feet however other variables also come into play.  Age, breed, use, nutrition, management, injury and disease all deserve great respect. Therefore, the tremendous need for us to continuously tune our eye for subtle little clues that can be of greatest value to our discovery exercise should never end. Recognizing the collaborating professional’s knowledge and skill level for the issue goes a long way to avoid misgivings, poor communication and even poorer results. This can often be confirmed with basic but relatively accurate sketches drawn by each professional that clearly describe what each sees and understands. This common thread is vital to assure success. Our keen observation is one of our greatest assets. It is one thing to see an object and quite another to understand the many very small details that hold the key to the information we seek.  It is not only our eyes that transfer information to our grey matter, but the summation of our other senses certainly compliments what we see and understand.  Experienced hands that have had hundreds even thousands of feet pass over the many prop receptors located in the finger tips and palms develop a memory for details that otherwise simply cannot compare.  This natural body memory can only be obtained with years of full time farrier experience. We all are creatures of habit and repetition is our go-to learning tool. Experience can be our greatest asset, especially if we are constantly fine tuning our senses for the smallest details.  Nothing hurts us more than a bad experience as it can wreck our confidence level and if we can’t quickly recognize the major flaws and source of our failures it can be tough to give it another try. I often hear, “I did it just like you said, and it didn’t work.”  This failure is multifaceted.  I may not have transmitted the info properly relative to the frequency of the receiver and taken for granted we were on the same page from the start.  It has always fascinated me to dissect what several different listeners think they heard or viewed and compare it to how they reveal what they really understand.  The receiver often says I didn’t think you really meant for me to do it exactly like your drawing as it seemed too simple to hold fine details. This is the point of this session:  to understand what we see, process the information by breaking it down into smaller, simpler components, and begin to make logical sense. Skill development follows keen observation, and both require a lifetime to reach full potential. The more we see, the better our skills for interpretation, planning the work and then working the plan. To start training the eye, I like to see an imaginary plumb line reference for most all external features.  We all have developed an eye for plumb since we were toddlers, as structural strength requires load to be plumb, Consequently, we do not throw this natural insight away when hanging pictures, posters etc. It is the norm, so let’s use it when observing the foot.  To simplify our perception of how the external shape relates to plumb, we need to view it in its purest form, which is perpendicular to the vertical and horizontal plane. Photos taken in this ideal plane are much easier to observe and thus eliminates image distortion that is produced by the bird’s eye view.  Once the eye is trained to repeatedly detect the various angles and unique characteristics in a disciplined methodical manner, the bird’s eye observation can quickly adjust the view from what has been previously learned, programed and second nature. Develop a visual system and consistently use it every single time you observe a foot without exception. I personally start by observing the toe angle.   Visualizing plumb and 45 degrees is quite simple as it falls half way between. Divide the upper 45 again included with the lower 45, which will equal 67.5 degrees, and you have an angle that mimics a lot of very upright feet and/or a higher-grade club foot. Now to visualize a relatively healthy toe angle hoof angle of 56 degrees, you are adding 22.5 degrees to the original 45 degrees, which is what you see in a healthy, robust foot. Another way to quickly determine the approximant toe angle is to visualize plumb and add or subtract 5 to 10 degrees relative to which side of the 45-degree imaginary line the angle falls.  As you observe the toe profile as well as the negative space around it you may find several planes to draw your line of reference.  Taking this into consideration, remember each strikingly different plane is there for a reason and influenced by the mechanical forces and their direct influence on the vascular supply to the horn growth centers.  This begins the thought process of better understanding the model.

2014 Equine Podiatry 101 Written and presented August 2014 by R.F. (Ric) Redden, DVM The term “mechanics” is a fairly new term the author uses to describe how the foot deals with energy and the forces at play. Large volumes of clinical evidence and observation of the very potent effects the deep digital flexor tendon (DDFT) has on the foot indicate it is the key to understanding the mechanics of the foot. The DDFT is the distal end of the large flexor muscle group that originates at the back (caudal side) of the forearm and is the source of energy for the tendon. The function of all muscles is to contract and relax. Contraction can be voluntary or involuntary, and apparently the degree and frequency of involuntary contraction has a variety of effects on different horses and even feet on the same horse. The DDFT passes through the back of the knee over the sesamoids at the fetlock, along the back of the pastern, over the navicular bone and attaches with an incredibly strong, fan-shaped anchor on the bottom and caudal aspect of the coffin bone. The tendon is quite strong and about the size of an index finger in most horses, however it can only stretch about 1% of its overall length. Therefore we need to think of it as a cable rather than a big rubber band. The ill effects of injury or disease to various areas of the foot invariably create a pain response and can greatly reduce circulation to an already weakened area. In turn, the action of the DDFT, which is still enacting the same force on an area that is now weak, can cause further pain, soft tissue and bone damage.  Our job as veterinarians and farriers is to first recognize the hot spots, assess the overall quality of the horn, sole and depth of cushion mass and develop a solution to address the mechanics required to reverse the forces at play (the DDFT) and give the damaged tissue time to heal. When we speak of increasing or decreasing mechanics we are referring to altering the distance between origin and insertion of the DDFT. Increasing mechanics means decreasing this distance, which in turn reduces the level of tension the tendon asserts on the coffin bone and associated structures. Decreasing mechanics does the opposite. Using sheer mechanics, we can reduce tension, compression and shearing force on several key components once we have working knowledge of how these structures work in harmony when maintaining optimum health. Suspension and Support The basic suspension system of the foot has three main components: laminae, coffin bone and DDFT. Visualize the laminae as Velcro or microsprings that attach the coffin bone and cartilage in the heel to the hoof wall. These springs basically suspend the bone within the capsule on three sides while the caudal aspect of the bone is suspended via the DDFT. The springs anchor firmly to the wall. Load passes through the digit, then the tendon and laminae. Apparently they become equally engaged as they allow the bony column to move distally in all conceivable planes. Working in tandem with the suspension system are the support components. The coffin bone rests on the sole corium, a blood-rich velvet cushion that houses the nutrient supply of the palmar zone of the bone and growth centers of the sole. When the highly flexible solar corium is compressed, circulation in this area is immediately impaired. This occurs naturally with every step, however when the foot has adequate mass (horn protection) and all components are in sync, natural recall of these structures exists.  If any one component becomes weak, injured or diseased a cascading series of events occurs that affects adjacent components. Simply put, we can’t have pathology in only one specific area. If one component fails, others begin to fail under the brunt of excessive load, tension and shear. By measuring soft tissue parameters on lateral radiographs we can visualize the repositioning of the coffin bone within the capsule simply by alluding to the position of the foot and load. Add the information gained from venograms and we have a live research model that offers a far more reliable means of tracking the influence of the DDFT than computerized models and/or cadaver limbs placed in load simulations. The data obtained by observing and recording the response of mechanical enhancement greatly helps us better understand the intricate interconnections of each component and how we can use this knowledge to enhance the healing environment. We can only observe the response to mechanics in the live horse, therefore the value of this information is well above all other data extrapolated from inert or cadaver models. Using mechanics to enhance the healing environment There are many ways to enhance the healing environment by using mechanics to shift internal load from a failing component to a healthier one. However manipulating the mechanics of the foot requires a reference or starting point. Palmar angle (PA), sole depth, digital alignment and tendon surface angles (TSA) are important parameters that are greatly influenced by the degree of tension exhibited by the DDFT under full load. These soft tissue parameters can help us better understand the level of tension present and design a specific shoe that best shifts internal load and tension to healthier areas of the foot. Wedges (pads or shoes), squared toes, reverse shoes, rockered toes and backed up shoes are all used in various ways to increase PA and/or decrease the energy needed for or in conjunction with breakover. All are beneficial to some degree but provide minimal mechanics as they only influence PA by a few degrees at best, if at all. This is great when only minor tension adjustment is needed to offset load on a failing component, however in many cases this simply is not enough to obtain the desired results. When static PA has not been increased, tension is not significantly altered until load is decreased as the horse takes a step. This is beneficial when the horse is moving, but has very little medical benefits when standing still for hours on end. The author prefers to use the rocker technique to accomplish a wider range of mechanical enhancement that remains in effect even when the horse is standing still. A great misconception exists among vets, farriers and trainers worldwide concerning the large scale of mechanics that exist. Knowing where, when and how to apply mechanics requires knowledge of the formula, accomplished farrier skills and ability to interpret radiographs, identify landmarks and design, fabricate and attach the shoes. Many of these requirements are certainly not part of everyday shoeing practices even at the top level and therefore can pose a problem for all who try to use the rocker technique armed only with good farrier skills and years of good experience. The mechanical formula puts therapeutic shoeing and equine podiatry into a new and exciting category all of its own. The great news is that everyone can get there given a strong desire to learn and eagerness for new challenges and skill development.

2014 Equine Podiatry 101 Written and presented August 2014 by R.F. (Ric) Redden, DVM Club feet are one of the most common deformities throughout the horse world. There are many unverified hypothesis regarding the trigger mechanism for this syndrome, however none have been scientifically proven. It is universally accepted that the deep flexor muscle fibers have an abnormal degree of persistent contraction, thereby shortening the overall length of the muscle belly, which creates a shorter distance from origin to insertion at the base of the coffin bone. The DDFT can only stretch about 1% of its full length and increased contraction suspends the caudal aspect of the coffin bone and increases the palmar angle (PA). The higher the grade, the greater the PA becomes. In the early 1980s the author developed very simple yet specific criteria for four basic grades of club feet. This simple classification system has helped vets and farriers better communicate and provides a precursor for developing a treatment protocol. See diagram below of the four grades. This syndrome affects the foot in several different ways to a degree that is relative to severity: The heels grow at an accelerated rate as they do not incur natural internal download. As the PA increases, so does heel growth. The heel, however, does not grow and push the horse upward. Rather the PA is suspended and the heel only lightly loaded, which accelerates growth. The frog is short, narrow and set well into the foot as internal download is inadequate. It is also suspended in a very unnatural position. The digital cushion becomes quite large and can be seen filling the heel bubs and lower pastern in mid to higher grades. It is also suspended as it is carried upward with the PA. Growth rings in the heel soon become wider as the grade increases and heel growth accelerates. Growth rings at the toe are diminished in width as the blood supply to the germal centers is compromised by internal forces. Therefore growth is slowed relative to the degree of contraction. The wall starts to dish, especially if the heel is reduced in height as a means to make the foot appear more normal. The bending action is the result of increased tension from the DDFT on the toe, which in most all cases is a weaker component than the tendon, especially in growing, developing feet. Sole growth is slowed or ceased altogether as a result of increased DDFT tension on the apex of the coffin bone, causing it to tip downward and press into the sole corium. The cup of the foot vanishes as the sole is pushed towards the ground surface. The coffin bone begins to remodel due to the unrelenting pressure of the very thin and very sharp-edged palmar rim against the sole corium, which compresses the blood supply that nourishes it. The wall at the toe becomes very thin and unable to protect the terminal laminae and adjacent sole. Cracks and fissures develop due to lack of adequate horn protection. Tenderness and lameness frequently occur because the horse is out of foot. If the foot is subjected to a wet environment and water, bacteria and debris find their way into the fissures described above. This often results in an abscess in the young foot that many times will break at the coronary band. Individuals that toe out tend to break on the inside of the toe, while those that toe in often break an abscess on the outside of the toe, and a few will break center toe. Reviewing the past history of many cases with unilateral white line disease, the author finds a direct correlation exists between white line disease and where the abscess breaks on a club foot. The vast majority of all white line disease cases have been in the club or higher heeled foot. How to manage the club syndrome Club feet can be managed by reducing the forces at play. Decreasing the tension on the DDFT relative to the required mechanical release greatly diminishes heel growth and accelerates toe growth. When this occurs, there will be rapid sole proliferation. The cup of the foot will reappear and the dish will grow itself off in a few months. Mechanics are a management tool that can offer a great option when surgery is not feasible. Most low grades clubs (1-2) do quite well by simply rockering the shoe at a point directly beneath the center of articulation (about the widest part of the foot) and loading the heel at the widest point of the frog, establishing a zero PA with the palmar rim and heel branch and maintaining maximum heel mass. Higher grade clubs (2 to 3) may require an inferior check desmotomy as an aid to lengthening the musculotendinous unit. Creating a 0° PA with the load surface of the shoe and a slight toe extension prior to surgery offers best results. Maximize the gap between the severed ends of the check ligament as much as possible at the time of surgery. PA should be weaned down slowly after surgery to prevent post op pain as many other structures are involved and need time to relax. A DDFT tenotomy may be required for the high grade 3 and 4 cases. This offers maximum lengthening of the musculotendinous unit. Even cases with a 40-45° PA are candidates for this procedure. The earlier in life the check and/or tenotomy is performed, the less scar tissue is present and the better the long term prognosis for athletic soundness. Surgery should be considered before irreversible bone damage has occurred. Surgical Approach When PA cannot be maintained and heel continues to outgrow the toe, surgery should be considered provided breed rules approve of the procedure. Inferior check desmotomy: Trim goals: establish a small flat area at the heel parallel to the palmar rim. Use an aluminum shoe glued on with Equilox. Avoid Equilox on the sole and protect any small fissures with wax or clay to avoid an abscess. The foot must be held up while glue is curing. Once the Equilox has cured apply a large wedge of Advance Cushion Support (ACS) or similar product and tape it on. This offers protective mechanics that prevent further damage as the shoe alone greatly increases DDFT tension. Leave the rubber wedge on for a few hours post-surgery, whether performed under general anesthesia or standing (the author’s preferred method). Trim 1/3 of the rubber height off every few hours or days as a slow wean down aid. This greatly reduces post op pain. Mid-cannon DDFT tenotomy: Secure the large ACS wedge with Elastikon and casting tape. The wean down process often requires 8-10 days. When too much wedge is removed the horse will show lameness and be reluctant to put weight on it. Post op care: Firm bandage for 90 days6 weeks stall restHand walk 2-3 monthsTurnout on firm ground in a small area for an additional 2-3 monthsFull tendon recovery is 1 year

Indepth Equine Podiatry Symposium Notes Written and presented January 2009 by R.F. (Ric) Redden, DVM If you were to be in a car accident, have a heart attack or suffer a severe injury most anywhere in America, a trained, competent EMT unit will come to your assistance within moments. Regardless of severity or type of injury, EMTs have a good plan in place, adequate training to deal with the problem and a well equipped unit. Their mission is to administer efficient emergency treatment and deliver the patient to the closest hospital for evaluation and appropriate treatment. This incredibly valuable service is state of the art for humans, but severely lacking in equine medicine. Veterinary medicine desperately needs an equine emergency medical team, well trained and equipped to deal with typical equine emergencies, whether they occur at televised sporting events, on the interstate or in the barn. Unfortunately, the need for such a service has never been taken very seriously. Consequently even at top level events such as the Kentucky Derby, veterinarians hired to be there in case of an emergency are often not trained for emergency scenarios, are poorly equipped to physically deal with most catastrophic breakdowns and have little or no direct experience with orthopedic surgery or knowledge of potential options that may exist for horse and owner. As a result horses are often euthanized immediately, sometimes in full view of the public, without the benefit of efficient emergency medical treatment and a thorough review of available options. The goal of any emergency medical treatment should not be to make a life or death decision, but to provide emergency aid and transport the horse to a location where a thorough exam can be performed by surgeons who are experienced with catastrophic injuries and the options available to them. Current Emergency Practices When a horse goes down on the racetrack or other sporting event, the typical scenario unfolds like this: the track or on call vet gets to the horse's side within minutes along with an ambulance that is capable of transporting most any injury once the limb or limbs are stabilized. The life of the animal rests solely in the hands of the vet who for all practical purposes is a well respected veterinarian, but has little or no experience providing adequate emergency care. Without experience or knowledge of state of the art surgical procedures or amputation, the availability of such options would never cross the minds of those attending a fallen athlete. Oftentimes the horse is euthanized on the spot, or he may be fitted with a Kimzey splint, loaded onto the ambulance and far too often euthanized on the backside, out of sight of the public. In some cases the horse may be headed to surgery only to be euthanized en route when the ambulance team believes the situation to be hopeless, a conclusion that may be supported by other surgeons who get a description of the injury over the phone. It is important to understand that everyone involved is doing the best they can, and making decisions they believe to be in the best interest of the horse. We simply do not have a well established plan that can be quickly executed in a timely fashion for all injuries, nor a proper training program to prepare veterinarians and other officials for these catastrophic injuries. To do a better job we must be better prepared. Pain as a Reason for Euthanasia The most common reason stated for immediately euthanizing an injured horse is that he is suffering inhumanely without hope of recovery. Owners have no choice but to agree with the conclusion of the professionals. But let's closely analyze this statement. The typical pain indicators used by veterinarians are heart rate and respiration. But a horse that has just run the race of his life or competed in a strenuous event will appear to be in respiratory distress as he pulls up, even when not injured. His cardiovascular system has been maxed out, and it will be several minutes at best before he can take a deep breath and not look as if he just saw a ghost. The horse with the broken leg looks essentially the same, so the usual indicators cannot be relied on. Pain is often confused with physical exertion and fear, which is caused when the horse can't find the limb to support them. This causes anxiety and even fear if he can't get away from a flailing limb. In my experience, all catastrophic cases I have treated became quite comfortable for hours to days after being fitted with a cast that stacked the bones and allowed them to load the limb. Was it painful? Strangely enough it was not for any of my former cases. Even when the limb was completely detached they would stand on the end of the stump, dispensing the thought that they should be euthanized as quickly as possible due to inhumane suffering. Therefore, pain is apparently not a good reason to immediately euthanize a horse before a proper exam has been performed and all the options considered. Alternative Options Last May, the filly Eight Belles was euthanized in front of millions of television viewers within moments of her catastrophic breakdown due to one badly broken lower limb and one suspensory apparatus breakdown. Either or both had surgical options that potentially could have offered her a quality life and given her owner, trainer, caretaker and farrier a chance to repay her for her brilliant effort, speed and courage as a super race filly, but the premature decision to euthanize her precluded any options from being exercised. I'm certain the fact that she injured both limbs played a role in the quick decision to euthanize her, but was this in the best interest of the filly, owner, trainer and industry? I do think it could have been a more acceptable situation had she received state of the art EMT and been moved to a local surgical facility for a thorough exam, review of the options and consideration of short and long term goals. While it still might have been most feasible to euthanize her following this preconceived EMT protocol, at this point euthanasia would at least be justified as all options would have been reviewed, discussed with the owner and the decision made accordingly. Orthopedic surgeons with good experience and an appetite for challenge have performed many successful repairs of some of the most horrific injuries possible. This option should always be offered to the owner and the horse. Even those that have irreversible loss of blood supply have options. While amputation and the field of prosthetics remain in the developmental stages, it is an option that has satisfied the requirements for a quality life for several horses. Eight Belles was on her side with a man on her head when the euthanasia injection was administered. How easy would it have been to apply a Kimzey brace on the suspensory breakdown and a short leg limb cast or long leg Kimzey brace on the bone fracture? At this point it was of little concern whether she had circulation to the distal extremity or what the prognosis was following various surgical options by those well experienced with this type of injury. Regardless of what the options ultimately are, emergency medical treatment must be administered to take advantage of them. Without medical evidence that clearly defines the severity of the injury there are few if any options other than euthanasia. Goals for Emergency Medical Treatment The duty of EMT personnel is not to make life or death decisions but to simply offer adequate first aid. The goal at this stage is to stabilize the injury, prevent further damage, reduce the horse's anxiety and either ship him to either a surgical facility or take him back to his stall for further valuation. Euthanasia should not even be the issue at this point. This means we have to develop a new mindset that takes the focus off diagnosing and treating the horse on site and puts it on stabilizing the horse and preventing additional damage while transporting it to a facility where those decisions can be properly made. A thorough exam of the damage and consideration of the options is vital to offering sound advice to owners and is the first step to formulating an efficient plan. Well qualified surgeons with years of experience can make it happen for some of the most horrific breakdowns and injuries provided the horse arrives alive and without further unwarranted damage. Priorities for dealing with catastrophic injuries: Concern for the health of riders, spectators or others that may be involved with the breakdown. Stabilizing the injured limb. Whatever it takes, make it happen. Calming the animal as best as possible. Providing a means of travel. We have some well equipped ambulances, but we need more. Protecting yourself as well as others from injury. Immediate concerns: Blood loss. Adequate bandage material, tourniquets, etc. are essential to prevent excessive blood loss. Sedation. Sedating a horse that has just maxed out his respiration and cardiovascular system is quite difficult. Do not expect to have a super quiet horse to apply a brace or bandage to regardless of what you use. Stabilizing the injured limb. Explosive pastern and cannon bone fractures can be quickly stabilized with the aid of a short or full limb Kimzey splint as indicated. The splint can be a great emergency tool and is even more valuable with the addition of an elevated heel that prevents excessive loading at the most proximal contact point. Casting. Five inch cast material over bandage or cast padding can be applied to the horse that is non weight bearing even when he is not standing still. It takes a little experience, but works great. A throwing harness can quickly and atruamtically lay a horse down to be restrained while a cast is applied. Good horseman experience is vital when dealing with injured horses, as they can kill, cripple or maim you without even knowing it. Potential Solutions Racetracks could set up a training program that would prepare the gate crew to address catastrophic breakdown assistance to track veterinarians. The gate crew is always at trackside and they are very experienced horsemen who can handle a tough situation. They are also already on the payroll, which would certainly ease up the financial obligations of the track. Mock up training sessions could quickly bring the crew up to an acceptable level of efficiency, and they would certainly improve with experience. New concepts and ongoing research and development in the field of emergency medical treatment would quickly change the mindset. With time and good experience equine emergency medical treatment would be standard procedure. Many of my clients, including animal activists, are eager and willing to support an efficient means of aiding our fallen athletes. A fund could be established for ongoing research and development in this field of service. EMT service could be a new vocation or business for those interested by the thought of providing a much needed service that doesn't currently exist. Orthopedic surgical advancements would be imminent given the chance and reason to pursue many catastrophic breakdowns. When veterinarians are called to train wrecks or other unexpected catastrophic breakdowns it is imperative to gather as much information as possible concerning when, how and why before heading to the emergency. Having adequate support and equipment upon arrival greatly enhances our efficiency and offers optimum outcome. Facing such a task armed with formal training and experience could turn a very tragic event into a rewarding experience for all involved. By simply changing our mindset regarding the goals of emergency medical treatment, we can drastically enhance the outcome of catastrophic injuries by offering our athletes more options, fueling new fields of research and assuring fans that the horse is our top priority.

Tips to Apply a Rockered (Banana) Shoe Written October 2005 by R.F. (Ric) Redden, DVM The rockered shoe is designed to enhance breakover. Square-toe shoes and other shoes that sit back under the ground surface of the natural toe also enhance breakover. But you must remember that "enhanced breakover" is a relative term. It is "enhanced" in comparison to what? When you square or rocker the toe of a flat shoe, the palmar angle remains the same when the foot is loaded. The breakover is enhanced but only relative to the distance that the breakover was reduced. This enhancement is only effective when the horse moves and has little to no mechanical advantage when the horse is standing still. This is fine if you don't need 24-hour mechanical enhancement. If you wish to greatly enhance the healing environment of the foot by establishing a self-adjusting palmar angle, you need a much more advantageous shoe. To obtain the shoe with the mechanics you desire, use this simple grading scale. For every 2 degrees of palmar angle you want your shoe to provide, score it 1 point. For example, 12 degrees of palmar angle would be a 6-point shoe (see radiograph below). Informative radiographs are essential to accurately assess the start model palmar angle, in addition to confirming the mechanics you need to score your shoe. 12 degrees = 6 point shoe I am often asked, "Does a farrier need an x-ray of every foot when he/she applies a rockered shoe?" The answer to this question depends on the goals of the client. Some may want to simply take a shortcut and apply the shoe with no blueprint. With no specific plan, the results you want are left to chance. When put in perspective, x-rays are relatively inexpensive in relation to the information they provide the vet/farrier team. Farriers that work with lame horses need to learn how to read informative, farrier-friendly radiographs. This will allow them to fine tune their skills when trimming the foot, designing and fabricating the shoe, and placing the shoe on the foot. Routinely reviewing pre- and post-shoeing film on pathological cases greatly enhances the chance for success. The more film a farrier reads, the more his/her eye for detail grows. The foot should reflect the radiograph, and the radiograph should reflect the foot. However, the finest details will be missed, even on a farrier's best day, without informative radiographs.

Indepth Equine Podiatry Symposium Notes Written and presented January 2009 by R.F. (Ric) Redden, DVM Amputation can be an option for horses that have suffered irreversible, catastrophic loss of blood supply to the foot, pastern, fetlock, cannon bone, hock or knee due to injury or disease. Typical cases may include acute and chronic debilitating deformities in young horses, explosive fractures involving the pastern, distal cannon, combination suspensory apparatus failure, extensive irreversible damage due to joint sepsis and extreme lacerations that destroy major arterial supply to the digits. Fractures of this nature can occur at high speed, be the result of paddock injuries and occur while in a stall or being worked on a lunge line. When determining whether or not amputation is a viable option many things must be taken into consideration. The personality of the animal is very important to consider. Aggressive, high strung, unruly or unbroken animals pose serious risk of injury for those attending to frequent surgeries and aftercare. Financial commitment can also be a determining factor, as a great deal of expense can be involved, especially if complications arise. The location of the injury (below or above the knee or hock) can also affect whether or not amputation should be attempted. Adequate surgical and aftercare facilities must be available and should include a 12 foot high beam system compatible with using an electric one ton hoist and sling, as after care is performed in a sling for the first 4-5 months until the horse learns to stand quietly without the sling for support. Aftercare personnel with good horsemanship skills will be necessary as well as a qualified farrier who enjoys mechanical challenges. The farrier should be open minded with the energy and optimism to make it happen, and willing to work closely with a veterinarian who also thrives on challenges. Ideal Candidates: Athletes who suffer an acute, catastrophic injury are good candidates for amputation as they are otherwise very fit and healthy and the opposite foot is most likely very healthy at the time of injury. Hind limb injuries at or below the fetlock would be the very best candidates; the second choice would be a mid to upper cannon amputation site on a hind limb, which would require a full limb prosthesis. Ponies and miniature horses (200-300 pounds) have a very good prognosis simply due to their light body weight. I have had several cases, and all have been receptive to the prosthesis. Prosthesis and stump management have been uneventful. Hind limb cases have a better prognosis than front limb cases due to less weight distribution on the hind end. Lower leg injuries have a better prognosis and lower maintenance requirements than mid-cannon amputations. Pastern or hind limb fetlocks require a short limb prosthesis (below the hock or knee). Mid-cannon, carpal or hock amputations and some front limb fetlock amputations require a prosthesis with an above the knee or hock extension. This can be hinged for select cases in front but a stiff, full limb works best for behind. Breeds that naturally have exceptionally good quality feet (thick and tough walls, 20+mm of sole with natural cup, 3-5 degree PA and strong digital cushion) can be reasonably good candidates even when contra limb laminitis affects the good foot. However, the laminitis must be manageable regardless of the degree of vascular damage and should always be the prime focus, as the good foot can deteriorate very quickly when laminitis is present. Standardbreds top the list of tough footed horses, followed closely by Tennessee Walking Horses. I often say you can't hurt these breeds with a running chain saw, as they are very durable with no limit to their pain threshold. Poor Candidates: Front limb injuries or disease that involves both limbs are not good candidates for amputation. Note that I classify these cases as poor candidates, not impossible. There is enough clinical evidence to suggest that bilateral amputation is possible and could be a viable option for select cases. Young horses with chronically painful injuries or disease that bow the opposite limb at the knee or hock are poor candidates as the opposite limb deformity remains a threat. As a rule it will continue to worsen with age and weight gain, which precludes all efforts to offer them a quality life even when the amputation and acceptance of the prosthesis are uneventful. Contra limb laminitis certainly diminishes the prognosis considerably when injury or disease has precipitated this frequently occurring problem. Laminitis in the opposing foot can be a major problem following surgical repair of catastrophic injury. Fortunately this common complication can be prevented in a large majority of high risk cases and can be treated successfully in most cases provided irreversible vascular damage has not occurred. Detection and timely realignment followed by a mid-cannon DDF tenotomy guided by evidence from comparative venograms can have very gratifying results even when it looks like all is lost to this devastating disease. This is where an ounce of prevention is worth a pound of cure. Cases that are initially treated surgically but deteriorate due to sepsis or major blood loss to the healthy tissue are poor candidates for amputation. Due to new, ongoing surgical developments many catastrophic injuries are now considered potential surgery candidates. Their ability to heal is based on adequate vascular supply, efficiency of fixation, temperament of the animal and uneventful aftercare. However, cases that are borderline for surgery due to the extent of the injury become far better candidates for an amputation than surgery, provided the decision is made at the time of injury and not weeks after it is obvious that the surgical approach failed to meet the criteria for returning the limb to a healthy, useful state. Contra limb laminitis is imminent in cases that heal slowly and have ongoing complications. Performing the amputation at the time of injury instead of attempting a very high risk surgery can offer much better long term results and bypass the risk of contra limb laminitis. Amputee pin cast cases are much sounder immediately following surgery than those with implants and cast. The problem with slow healing or complicated surgical cases is that they will show no signs of contra limb laminitis until the good foot becomes more painful than the surgical leg. By this time laminitis has been present for several weeks and tremendous vascular damage has occurred. However, if the initially injured limb is 80-90% healed when laminitis is detected good results can be obtained by realigning the palmar surface with the natural load zone (derotation) followed by a DDF tenotomy. When performed in a timely fashion, most hind limb contra limb laminitis cases have a reasonably good prognosis. Financial Obligations: In my practice the average surgical procedure with fitted temporary prosthesis runs between $6,500 and $10,000. Hospitalization may average $150-200 per day with up to five months of hospitalization. During the five month recovery period at least two additional surgical procedures are indicated. The first is a frog graft performed within the first two weeks of the initial surgery or when the granulation bed is most receptive and the second is pin removal and re-casting. Each requires general anesthesia and can cost between $1000 and $1500. All subsequent cast changes are performed in the sling (when the patient is cooperative) every 2-4 weeks depending on stump response. A permanent prosthesis can be fabricated approximately 5 months post op, and runs between $1,500 and $10,000, depending on the level of detail involved. Complications can incur additional expense and can include pin failures, premature bone failure around the pins, spiral fractures, septic stump and long bone fracture above the prosthesis. All are low risk, but possible. It is extremely important to discuss the financial commitment, both immediate and long term, with the owner before electing the procedure. Many cases can go on to be low maintenance and the projected budget held in check, but the possibility of complication and unexpected costs should be clearly communicated so that everyone can be on the same page and prepared to meet financial obligations. Amputation Procedure The procedure can differ greatly depending on the level of amputation, therefore it is extremely important to have a good plan in place that has been well established and well rehearsed with all participants before proceeding. A good back up plan is also important as there is no time to think about plan B if it has not been rehearsed. Several surgeries are involved, including the initial amputation and pin cast, followed by a frog graft surgery 2-3 weeks later and pin removal 4-6 weeks post op. Complications could require additional surgeries. Thorough preparation, necessary equipment, and an adequate temporary prosthesis with necessary tools to quickly modify it should all be in place before the surgery is attempted. It is best to use general anesthesia for the initial surgical procedure. Not to say it can't be done in a sling, because it has, and has been quite successful. I assisted an orthopedic surgeon in 1974 on a standing amputation. We made it happen, but we almost lost the surgeon a couple of times. A standing amputation in a sling can be a bit hairy to say the least. Necessary equipment: A sling setup is extremely valuable for optimum success. A support sling that can be used for induction and recovery and for follow up temporary cast changes is imperative as this optimally protects the bone at the pin sites. Ceiling height should be a minimum of 10 feet, preferably 12, with an adequate overhead beam that will support well over 1 ton. An electric 1 ton hoist (preferably with lift rate of 16 feet per minute or faster) is also standard required equipment. Creating a temporary prosthetic: The size of the stump may change periodically for the first five months post op, therefore a temporary prosthetic is necessary until the stump heals. Very economical temporary prosthetics can be fabricated in a matter of minutes using a 1/4 inch aluminum plate, cast material and an aluminum pipe. Qualified, experienced farrier services are a very helpful adjunct to therapy, as farriers have a natural, mechanical thought process that can greatly assist the creation of a temporary prosthetic. PIII and PII removal: When the heel bulb, frog or even part of them remains viable I use them as an autogenous graft, removing the diseased tissue, hoof capsule, PII and PIII. This has worked well several times. Fetlock removal: Front limbs present a problem as the limb becomes very round and the shape of a baseball bat. All prostheses need to have a bulb or large distal end to prevent it from falling off. However, in front the prosthesis will rotate around the stump. If at all possible I retain a section of PI that can be used at an angle to prevent rotation of the prosthesis. Hind limbs do not pose this problem as the cannon bone is quite flat, which prevents the rotation when fitted properly. Mid-cannon or higher removal: Hind limbs require a full limb to prevent it from falling off and twisting. A rigid prosthetic works better behind than a hinged one, but on front limbs a hinged prosthetic can have advantages over a stiff limb. Pin cast: Pin placement is like a lot of other procedures. Surgeons choose sites based on past experience. I personally like to place the first one just above the distal condoyle and the second one at an angle to the first, one inch above and tipped slightly out of the parallel plane. I prefer to use Procel Cast Liner padding directly on the skin followed by a close fit cast over the protruding pins. I routinely fill the cap from a 3cc syringe casing with a broad spectrum antibiotic, place it over the end of the pins and then cast over it. This helps prevent the pins from working through the outer cast and hopefully keeps bacteria at bay. I often remove pins standing without sedation when I feel the stump has done exceptionally well. Pin breakage can occur with any and all pin sizes due to cyclic rhythming and can occur within days to weeks from the time of implant. The bone will invariably wear around the pins as this is the weak link in the support system. I have gotten as long as 9 weeks from a few pins and as short as three weeks with others. Very soft bones that are commonly found in chronically lame cases can pose an exceptional high risk for bone failure. But what is the risk when euthanasia is the only other option? Complications: There are several complications that can occur following amputation. It is extremely important to monitor the patient with frequent observation and radiographs so that problems can be detected and corrected early. Complications can include: Pin failure. It is not uncommon to have a pin break in the first few weeks. Threaded, positive profile pins offer slightly longer use. Bone failure: Fractures can occur around the pins in 3-9 weeks. Spiral fractures, which are usually catastrophic in nature, can also occur. Failure of the stump to heal. Stump complications can occur due to excessive bone remodeling followed by sepsis of the stump, which can require an additional procedure farther up the limb. Unexpected injury during recovery. Sling recovery can be uneventful, but it can also get a bit hairy. Long bone fracture above the prosthesis Contra limb laminitis. When the initially injured limb is amputated contra limb laminitis is a threat. A properly fitted device that establishes and maintains an 18-20 degree PA can prevent laminitis in a large majority of high risk cases. Permanent Prosthesis: At five months the stump has normally reached its maturity and has a consistent size. A mold is made of the stump and upper limb when a full leg is indicated. The angle, length and overall design are presented to a prosthetic specialist with good equine experience along with the mold and design. A permanent will normally last several years, but will ultimately need to be replaced as the plastic is UV sensitive and breaks down after long term turnout. For clients with a lower budget, a temporary prosthetic can last several months even with turnout, mud, rain, etc. and can be used in lieu of a permanent. Most human prosthetic specialists like to make equine prosthetics fit much like they do on humans, which is very tight. This is a terrible mistake for horses, as the prosthetic will only fit one time. When it comes off for the first time the leg will swell. It won't fit again unless the stump is forced into the cup, which creates even more swelling. Those making the prosthetic need to be well aware of this potential problem. Quality of life: When only one hind limb is involved, my best cases have been low maintenance once they have been trained to stand without the support of a sling for a routine prosthesis change. Some learn quicker than others, and good horseman skills are needed to teach this invaluable part of maintenance. Most stumps need attention every 5-10 days. The leg should be washed, dried and re-bandaged for the prosthesis. Those with good frog pads need to have them trimmed every 3-4 weeks as they can grow very quickly. Their basic maintenance program must be in place and consistent, with good stump management for the remainder of the horse's life. This requires good horsemanship skills and an eye for detail. The stump should be regularly examined for subtle changes that may point to future problems. My hind limb cases were all turned out in a one acre paddock 4 1/2 to 5 months after amputation and were surprisingly happy, able to gallop, buck and play. Front limb cases are not as free to move quickly, but can trot and canter with lower limb amputations. One of my full front limb cases met an early demise when the prosthesis got caught in a stall door, fracturing the radius. A stallion with a mid-cannon amputation has survived for several years, even breeding a few mares live cover. One filly that had PII and PIII removed is reaching her 17th year as a 24 hour turnout, low maintenance case. She gallops freely with other horses and defends herself quite well with aggressive horses. In other cases, embryonic transfer has been utilized as a means for mares to remain productive, which reduces excessive load from pregnancy. Amputation is not an exact science by any means, but given a new mindset more cases will be considered for this procedure. The downsides of amputation are still better than immediate euthanasia with no effort, imagination or determination to make it happen. This has been a very rewarding part of my professional career and I encourage others to share in my enthusiasm and one day make it a common practice for the fallen athletes or those that face certain death due to a devitalized limb.

2001 - 14th Annual Bluegrass Laminitis Symposium Notes New Developments Using the Four Point Concept Written and presented January 2001 by R.F. (Ric) Redden, DVM The strength of the four point trim concept continues to grow as I find new ways to apply the magic “pivot point” to the foot. This concept has the ability to transfer load and effect the tension in the suspensory/tendons of the equine digit, which appears to be directly related to the reperfusion of compromised growth centers. Reperfusing these vital growth centers greatly enhances the genetically programmed healing response of the foot. Many people ask, “How does this method differ from traditional shoeing?” and “How do other versions of the four-point method differ?” The answers to these questions are as varied as the number of farriers using the four-point trim, but the basic formula remains the same. Traditional shoeing is basically designed to protect the foot while offering little or no mechanical aid to enhance perfusion of the sole corium and laminae. It also fails to attenuate the tension of the deep digital flexor (DDF) tendon as it courses over the navicular bone. Today’s definition of traditional shoeing can be traced back a couple of hundred years at best. Do you ever wonder, “What was considered ‘traditional’ before this?” Shoes worn by horses throughout Europe and Scandinavian countries hundreds of years ago are displayed at teaching institutions and museums, while thousands of others are in storage. Most differ greatly from the traditional shoe of today or even of the shoes that made their way into the first few books written on the subject. I challenge those individuals who decry the four-point concept as not being “traditional”. This concept is actually so old that it is now new again. Hundreds of years ago, horses wore shoes designed to enhance the blood flow to the foot; and therefore, aid natural healing. These shoes were used well before present day shoeing standards were altered by more recent writings. It would be interesting to know when and how the farriers of Columbus’ era discovered the strong influence of placing the breakover well behind the apex of PIII. Obviously there were no x-ray machines at that time, so the only way to discover the location of the bone in relation to the shoe would have been to cut the foot and shoe down the sagital plane. I am certain that some who were inspired to move forward did just that. How does the four-point concept work to enhance the healing environment of the foot? Apparently a very delicate equilibrium exists between the flexor tendons and suspensory structures of the foot. When in harmony, these groups act as a unit with a multi-complex function. The laminae, especially the anterior two-thirds, are a direct antagonist of the DDF tendon. The extensor tendon that attaches to the most proximal prominence of PIII is also an antagonist of the DDF, but it is considered the weaker of the two. Furthermore, the coffin bone is supported within the capsule by the laminae, chondral collateral ligaments, impar ligament, the sole corium, sensitive frog and digital cushion. The laminae along the posterior half of the foot are also attached to the flexible ungual cartilage. Apparently, this cartilage is a very forgiving structure that significantly prevents laminae sheering in most laminitis cases. The entire system rests in the sling of the DDF that is multi-functional itself. For the sake of discussion, lets simplify the biomechanics of the digit and develop a meaningful and useful alertness for the load sensors and their caution lights. Lets assume a large majority of the horse’s weight is resting in the sling of the DDF. This weight extends through the tendon, down the cannon bone and across the proximal sesamoids. It makes a turn and continues down the back of the pastern, followed by another abrupt turn under the navicular bone where it attaches to the base or semi-lunar surface of the coffin bone. Remember that the bone is rigid. It is attached to the laminae and a very flexible, highly sensitive blood barrier, which are both attached to the semi-rigid hoof capsule. As down load is placed upon the limb, each structure comes into play. If we see the tendon as if it were a large “rubber band” attached to a highly sensitive coil (the muscle) programmed for delicate suspension, we can imagine the weight of the horse passing through the fetlock and lower digits causing them to reach maximum flexion. If the suspensory is cut while the limb is in full flexion, the fetlock will remain very close to the ground. The suspensory is the major support for the fetlock joint. However, if the superficial tendon is cut, the fetlock will come up but not reach its original height. If the DDF is cut, the fetlock angle returns to its original relationship with the pastern. Notice that cutting the DDF doesn’t affect the fetlock angle. Instead, it causes major changes within the hoof capsule. Apparently the suspensory is the major support for the fetlock while the DDF is the major support for the third digit. Radiographically, the coffin joint can be luxated as much as one-fourth inch depending on the unique characteristics of the digital alignment and the relationship of the hoof capsule to the ground. After cutting the “rubber band,” the DDF tendon releases the down load that was once cradled in the sling. Therefore, the sling no longer exists. There is no longer direct pressure over the proximal sesamoids, the navicular bone, bursa and sole corium. PIII also floats forward because there is no structure left to hold it tightly against the articulation of PIII. The impar ligament is a very strong attachment capable of supporting serious down load. When the DDF is cut, it also moves forward with the bone. The apex of PIII also tips upward as load is passed through the proximal digits to the articular surface of PIII. In absence of the support sling, the apex of PIII is pushed upward and forward. PII also moves in a posterior direction, transferring load to the caudal articular surface, navicular bone and impar ligament. So, what has happened to the original pressure points? The distal sesamoid acts as a pulley over a high-stress area to reduce friction and absorb energy. It also supports the coffin joint along the palmar surface. This hot spot is a high friction point, but the cutting of the “rubber band” has significantly diminished the amount if friction. Subsequently, the pain associated with this spot is immediately relieved. In addition, pathological lesions involving the tendon, bursa, bone or supporting ligaments are no longer tightly compressed against the opposing forces of the DDF tendon. The palmar surface of PIII is concave with a very sharp solar margin along the anterior two-thirds of the bone. A student of mine once commented that, “it would make a terrific hatchet”. There is no doubt that this very thin, fragile border of PIII plays a role in its function. The question is, “How?” When the sling is cut the bone tips upward, the action immediately releases down load against the very sensitive sole corium. Performing venograms on numerous sound feet with acceptable mass and “balance”, I found that lateral views revealed that the vascular complex of the sole measures one full centimeter in depth. The circumflex vessel is palmar to the surface of the bone and slightly outside the cutting edge of the bone. In some cases, the thin-soled horse may have only one centimeter of total distance between the bone and shoe. The venogram reveals that the circumflex vessel is sandwiched between the wall and the bone. This serves a nice hiding place otherwise the cutting surface of PIII could cause irreversible damage. Suddenly relieving the down load against the delicate vascular supply not only relieves pain (the hot spot is no longer there), but it allows the vessels to perfuse (fill with blood) as never before. Observing the effects of literally hundreds of cases that were realigned immediately prior to a tenotomy, it is evident that perfusion results in sole proliferation. Relieving this hot spot in acute laminitic cases is a major contributing factor for successful treatment. The bone acts as an anchor for the sensitive laminae, which basically remain functional as long as the basement membrane remains intact. When the function of the basement membrane is compromised, the desmosomes lose their adhesive strength and are pulled apart by the relentless pull of the DDF tendon. When the tendon is cut, this pulling force no longer exists and the desmosomes continue to remain intact. Anatomically, the sensitive laminae are attached to the non-sensitive laminae, which are the inner zone of the hoof wall. Migrating abscesses can form puncture wounds, keratomas, white line disease, cause pathological lesions of the zone and subsequently cause pain due to the close association with the sensitive laminae. This semi-rigid zone extends along the entire circumference of the hoof capsule. At the inner sole margin the laminae become modified and form the sole wall junction. These terminal laminae can be seen on the ground surface of a freshly trimmed foot and are erroneously called the white line. To be accurate, it is actually more yellow/yellow-brown than white. Adjacent to this zone is the stratum medium, which comprises the bulk of the hoof wall. Its growth comes primarily from the secondary laminae. It is non-pigmented and appears white in color. Often it is erroneously referred to as the anatomical white line that was previously mentioned. It is the only white line on the exterior of the foot. This zone is continuous to the top of the coronary groove and is the primary site for white line disease. When treating white line disease, one key ingredient is relieving the downward pull of the tendon against the bone, and the bone on the hoof wall. This action significantly reduces the tearing forces placed on the wall. When looking at white line disease radiographically, a large lucent (dark) area can be seen just in front of the bone. It has an entirely different shape and location than the dark zone found with laminitis. However, the forces at play in both white line disease and laminitis are the same. The DDF is just pulling the wall apart instead of destroying the laminae. In both syndromes, extensive rotation and acute lameness can be evident. The outer horn wall is made up of vertical tubules placed in close proximity. These tubules give stiffness, yet flexibility, to the wall. The growth of horn wall originates at the coronary groove. When this horn wall makes contact with the ground surface, it forms bars as it wraps around the bulb of the heels. The result of cutting the DDF tendon immediately reduces the inner pull of the bone/laminae network, which significantly reduces the bending or dishing of the hoof capsule. The ground surface of this zone is the farrier’s workstation. Whether trimming or shoeing the foot, how the outer hoof wall contacts the ground or shoe surface is of the utmost concern. It is this zone that sets the stage for the counter action of the DDF tendon. This is a short, basic summary explaining how the four-point system enhances natural healing by simply eliminating hot spots and subsequently enhancing perfusion. The four-point concept is a conservative technique with very similar mechanical advantages found with a tenotomy. Moving the pivot point back from the toe attenuates the tendon pull by simply reducing the counter pull. This is referred to as ease of breakover; the further back it goes the less pressure placed on the hot spots. I refer to increasing the mechanics of the trim or shoe as reducing counter pull that opposes the tendon. Requesting a farrier to rocker the toe is meaningless unless a point of reference is used because all rockered toes have mechanical advantage. On a scale of 1-10, with 10 being equal to a tenotomy with normal digital realignment, most rockered toes fall into a 2-3 category. This is not bad. However, if you need quick results, quick growth, quick pain control, and optimum healing you need higher-scale mechanics. In the late 80’s and early 90’s, I used a rocker toe technique on horses with chronic toe cracks, dished feet and thin soles. I also used this rocker toe trim to unload diseased, frayed yellow lines that had multiple black splits and associated horn cracks. The breakover or pivot point was placed on the foot perpendicular to the long axis of the frog, approximately 1/2 to 3/4 inch forward of the frog. The heels were pushed back to the widest point of the frog when possible. Simply unloading the areas that seemed to always pack dirt drastically reduced the number of gravels seen during wet weather, and it stimulated tremendous sole proliferation. The four-point shoe soon followed as many mares were thin-soled, making it very difficult to move the breakover back to within 3/4 inch of the frog. My trim and shoe have slowly evolved over the years, and I am almost at the same rung on the ladder as my colleagues were 400 years ago. There has been some progress made because my four-point method now allows me the opportunity to help a multitude of problems with very consistent results. My first four-point shoe had a square toe that put breakover approximately 3/4 inch forward of the frog, very close to the apex of PIII. I had great luck treating many thin soles and shelly walls, some with a heavy dish and full thickness toe cracks. I wasn’t satisfied with this shoe as it left a lot of toe hanging over the end of shoe. A horse that would paw a lot could easily bruise the exposed sole wall junction. I shod many of the world’s best Thoroughbred stallions and mares with this design and helped them all, however the shoe had its drawbacks. Once I have identified negative aspects of a shoe, pad, nail or clip or a combination of all the above, I delete it from all future shoeing protocols. The square toe was deleted and replaced by a shoe with full toe cover and breakover at the widest point of the shoe. This gave me both protection and high-end mechanics. Personally, I have no problem with any or all of the four-point concepts that float around the globe today. All four-point shoes have mechanical advantages that attenuate the tension of the DDF, relieving compromised growth centers. Still, there are questions that persist. “How quickly do you want things to happen when shoeing a lame horse?” “What do you expect to see in four to six weeks?” The answers to these questions depend on where you place the breakover. Ask ten farriers and you will get ten difference answers. Personally, I want a lot of foot growth in four to six weeks to protect sensitive areas. I feel my technique is an overkill compared to others, but I find great success with rapid sole proliferation. Plus, new sole triggers new wall growth. Where shoes rank on the mechanical scale is dependent on where the pivot (breakover) is place relative to the apex of PIII. There is not a hard rule of thumb that describes the ideal breakover for all feet. Internal as well as external hoof characteristics influence the PSI needed to lift the heel from the stance position. Many other factors influence the lifting of the heel as the horse is propelled forward. One would like to think that breakover 3/4 of an inch in front of the frog would have the same effect on all feet. However, experience has taught me better. The long toe-underrun heel foot with a –5 to –10 degree palmar angle and a 2.5 - 3 inch digital breakover often requires the pivot point to be well behind the coronary band. The opposite foot that is most often a grade 2 to grade 3 club with a +8 to +10 degree palmar angle has the center of load closer to the apex of the frog. This observation has taught me to adjust the pivot further and further under the foot when optimum mechanics are required. This aggressive breakover technique has offered my patients a quicker recovery time and allowed them to return to training much quicker than with my previous point of breakover. Contrary to the published materials that caution against placing the breakover behind the apex of PIII, I find it very useful and a means to relieve compromised growth centers. Case 1 The case presented as a Grade 3 club foot with a dished hoof wall and growth rings twice as wide in the heel than in the toe. There was also slight remodeling of the apex. This foot was more narrow relative to the opposite foot, it had a prominent coronary band, 6mm sole depth, and was shod 3-4 weeks prior with a four-point rocker rail and 10-15mm breakover. Response There was 12-15mm of sole growth by the first reset (four weeks) and a slight reduction in the growth ring pattern. The second shoeing revealed 15-20mm of sole with slightly more toe growth than heel growth. The dish was almost grown out with the foot having never been backed up from the front. The third shoeing revealed a foot absent of a dish, 15mm sole depth with 5-8mm cup, and even toe/heel growth patterns. Placing the breakover well behind the apex of PIII with an aluminum rail or air wedge rocker offeres me a consistent means of treating club footed yearlings with thin-soles and poor quality walls. Using the venogram to demonstrate the simple physics on healthy feet, as well as diseased feet, we can identify areas of perfusion, the degree of filling and the areas with limited perfusion. Simply moving the breakover to the apex of PIII significantly increases perfusion of the sole corium and anterior lamellar vessels. The Redden Modified Ultimate with the breakover directly beneath the apex of PIII has a very similar pattern when films are made during the final stage of infusion while the limb is fully loaded. Perform a venogram on a sound, healthy foot: Hoof angle measures 54-56 degrees HL zone measures15/15mm Sole depth measures 20mm Digital Breakover measures 35 mm Be sure to load the foot during infusion of the contrast agent by picking up the opposite limb. Take all necessary film within 30 seconds. Your results will show stark loss of contrast along the lamellar vessels and sole corium distal to the apex. Apply a four-point trim to the same foot pushing the heels back slightly and placing breakover at the apex of PIII and repeat the experiment. The laminae and sole corium routinely perfuse within normal limits. A similar pattern can be seen using the Modified Ultimates. Therefore, consistent data points to the action of the DDF tendon as the great mediator and clearly explains how we can consistently raise the heel on laminitic cases and use the four-point method on a multitude of pathological conditions with consistent success. The four-point concept carries a strong message, and the results are dependent on the start model, the power of observation and skill of the farrier. Farriers without radiographic vision have a tremendous disadvantage. Knowing how to read informative film gives us all the opportunity to become more proficient in our perception of what lies beneath the sole. Failure to accurately assess the start model can have serious consequences for those trying to use the four-point technique without fully understanding it. Misjudge the sole depth by 10mm and you have a very sore horse with the best part of his foot lying on the ground. Raise the heels on a laminitic horse with 5-10 degrees rotation, positive or negative, and you bite the dust without realigning the load centers. I hypothesize that the four-point technique enhances the so-called “pump” of the foot. It is also my hypothesis that it is the action of the DDF tendon that significantly reduces blood flow to the anterior laminae when it is loaded and allows it to fill rapidly when unloaded. Could this be the mystery pump? I think so. Moving large volumes of blood throughout the laminae with each footstep would be a logical explanation for the natural cooling system that prevents over heating when the foot is subjected to speed. It may also help argue the frog pump theory that most of us never bought anyway. The ungual cartilage must also play a role as an energy sink, (ref: Bowker). Hopefully future research will give us many of the answers. My message to everyone is to relax and let the foot speak to you. Observe the effects of your efforts, whether they are positive or negative. Delete the known negatives and enhance the positives, use informative radiographs at all times, and the mechanics will come to you.

Falling Springs Theater, Versailles KY In-Depth Short Course R.F. Redden, DVM June 1-3, 2007 Focus on the mission Before we take radiographs or review those of others, we must understand what we need to learn from film and how to use information that we were not expecting to find. To seek information we must have a very specific, repeatable method that delivers consistent imaging, horse after horse and foot after foot. There are many variables that can interfere with consistent imaging that we need to identify in order to achieve optimum information from film. There is not a reliable standard set of views that adequately cover the broad spectrum of information we seek concerning basic pre-purchase exams, repositioning film and lameness exams, as each exam must be tailored to meet the demand of the specific information we seek. Taking repeatable views in an effective fashion is the first step to understanding the information we seek. Inconsistent imaging greatly diminishes our ability to learn the vast range of norm that exists between feet of various age, breed, diet, use and environment. That said, it is not surprising to experience frustration when trying to interpret the vast range of pathological lesions. Farriers play a very intricate role with the overall health of the horse. As we all know, no foot, no horse. The meaning of this saying is quite obvious to veterinarians and farriers who team up to sort out career and life-threatening problems. Why do farriers need to know how repeatable, informative views are actually made? Having that knowledge greatly enhances their ability to learn to read the signature of the shadows as it relates to their task and responsible role as health providers. Farriers who can read and interpret vital soft tissue parameters that are influenced by the rasp, shoeing knife and shoes become a tremendous asset to the vet-farrier team, as unlimited options are made available through this information. On the other hand, veterinarians who have a good working knowledge of those same parameters and how they change due to growth, routine farrier maintenance and pathological syndromes greatly enhance their ability to provide the farrier with timely informative film and medical knowledge that is beneficial to the team effort. The benefits of knowledge are powerful and the basis of progress as vets and farriers use film as a common source of information relative to their roles as team members. How to Make Consistent, Informative Film Standard views have been suggested as a relative means to accurately assess the health of the structures of the feet, the thought being that with a few standard views we can adequately reveal common pathological conditions that often affect feet. This is true in part if we simply look at film for what they can reveal. However, stepping out of the box and using our own x-ray equipment to answer specific questions we may have concerning a specific foot puts new life into our pursuit of discovery. Beam selection is of utmost importance. There are several factors that we must consider when selecting projection angles. Radiation travels in straight lines much like light waves, but it leaves the machine in a way that is similar to shot gun pellets leaving a gun. Using this simple analogy let’s follow the path of each pellet, which traveling along a straight line penetrates some part of the subject (in this case, the foot) and becomes imprinted on the film, leaving information relative to how hard it hit the film, if at all. Each pellet creates a slightly different image relative to the angle it entered and exited the foot, how fast it was traveling and how much stored energy (mass and velocity) it had. Soft tissue exposures require less energy to penetrate than bone exposures. Therefore we will speak of soft, medium and hard penetration throughout this course. The softest penetration reveals an image that clearly demonstrates the shape and densities of the hoof capsule. A severely underexposed film will reveal only the outside margin of the hoof. While even the hair will be visible at the coronary band, the bone image will not be identifiable simply because the energy behind the pellets was not adequate to penetrate bone. Thus, they never reached the film. The hardest penetration will reveal only the densest bone. Other softer or less dense areas will not be visible with normal fluorescent back lighting as the film was bombarded by the kinetic energy delivered by the overkill, so to speak. Both extremes contain information specific to that degree of penetration. Soft tissue views offer valuable information for the podiatry team where harder penetrating views offer the veterinary surgeon and diagnostician valuable information concerning the state of health of the bone. Therefore, to gain optimum information relative to the soft tissue and bone, different machine settings and beam positioning must be considered to cover the large range. A standard technique that provides the information necessary to diagnose and treat a large variety of foot ailments does not exist. How is the Image Created? To simplify the basic 101 geometry of radiation, we can visualize each pellet traveling along a unique pathway that was determined as it exited the focal spot or energy release center. Each pellet will enter and exit the foot at a slightly different angle than the one next to it. When it strikes the film, a series of small dots will be imprinted on the film that describe not only the angle the pellet took through the foot, but also the angle at which it hit the film. Much like the spray of pellets from a shotgun shell, radiation traveling from the center of the explosion has the shortest, most direct rout. When headed in a perpendicular plane with the cassette and film, the image produced at this point is quite pure relative to the distortion that is produced as pellets land at an angle relative to the cassette. With low MAS output portable machines, this area appears to be approximately 25mm in diameter on the film. Pellets that travel away from their center core create slightly different shaped dots when they contact the film at an angle. The further away from the center shot, the greater this angle and the greater the distortion of the image. Therefore the image transferred to the film is relative to the route the light beam or pellet traveled through the foot, meaning beam selection is the first priority. Optimum images can only be created by knowing what you are looking for and placing the center beam on the specific area while remaining parallel to the ground surface. The foot must be on the same plane as the machine. Perpendicular film/beam relationship must exist in order to prevent unwarranted distortion of the image. Select the penetration energy (MAS and KV) that will offer the desired image (soft to medium to dark). Film/Subject Distance The distance between the foot and film should be zero to prevent unwarranted magnification. Why is this so important? Using my soft tissue parameters protocol requires an accurate image to justify measuring precise soft tissue space zones. When the image is magnified, the horn-lamellar (HL) zone and sole depth (SD) measurements are also magnified. The farther away the plate is from the foot the longer the magnification. Having the cassette touch the foot sets a benchmark for the standard foot film. When shoes, pads, bandages, etc. hold the foot away from the cassette, you should make note on the film jacket as such. Otherwise future references to this film may be less meaningful. The image created on the lateral view represents the sagittal section of the foot. A three inch foot (width measured at the widest point of the foot) will measure 1 ½ inches from center line to cassette while a 6 inch foot will measure 3 inches. If we saw a cadaver foot along the sagittal plane and turned the cut surface to the cassette we would find a smaller HL zone and a thinner sole than if we radiographed it intact, simply due to magnification created by the distance from the center line to the cassette. Of course we cannot overcome this degree of magnification, but we can certainly control the film/subject distance with every exposure. Make zero the standard 100% of the time. Let’s back up and realize the importance of how to position the horse. Sedation when possible or feasible is a tremendous aid for taking properly positioned exposures. Use two blocks made specifically for the x-ray unit of choice. Preferable beam height is ½-¾ inches over the block. Why should we use two blocks? Did you ever wonder what a lame horse was thinking as you tried to make him stand on one block for the sake of getting radiographs of his lame foot? One block is not compatible with pain tolerance and often requires heavy sedation, twitching with lip chains or even blocking, all of which are totally uncalled for as they hide enough pain response to take the film, but in turn potentially create a larger problem than you had to start with. Compassion for the animal must always be foremost in our minds. Using two blocks makes the process much easier. A very small dose of sedation, .25 to .3cc IV of Dormosedan normally works quite well for most cases. Set one block next to the sound foot and the other beside the lame foot. Let the horse stand very quietly until he reaches optimum sedation. He will normally shake his head just before sliding into a relaxed position. Quickly push him over onto the lame foot, pick up the sound foot and aim it for the center of the block. This has to be a quick, calculated move, which you will get quite good at with experience. Quickly go to the lame side and place the foot on the block, as it is now basically unloaded. The horse will be quite willing to bring it up to the same level as the other foot. Observe the stance of the animal before picking up the feet. If he stands toed out in one leg or the other, place the blocks in that position and note the chest width. If, for example, there are 2 inches between the legs, set the blocks 2 inches apart. The goal is to obtain as a true a representation of static full leg stance alignment as possible. A visual plumb bob alignment of the limb in both lateral and DP views should be part of your standard protocol. Always strive to avoid misrepresentation of the digital alignment, joint space and medial-lateral balance, which can occur as a result of less than perpendicular load stance. Exception to this standard is when the horse is quite lame. In these cases, you should have already thoroughly examined the foot and developed an idea of what you are looking for, and may prefer not to cause further pain or unwarranted problems. Setting the lame foot way out front on one block can offer adequate information to help rule out fractures and extremely thin soles (found with laminitis, white line disease and other problems) before you block the horse for more informative views. Keep the horse’s head straight ahead when taking lateral and DP views for balance or soft tissue parameters, as the toes follow the nose of the horse. When the horse looks left, the limb torques left, and when the foot is stationary joint space and lamellar attachment changes even in the healthy foot relative to the increased load. Make this part of your standard and you will never have to second guess why the joint space is somewhat larger on one side than on the other, or if the medial listing is real or created by the turned head. Shoes on vs. Shoes Off Contrary to what we have all been taught, lateral and DP soft tissue views with the beam just below the palmar surface and the shoes on offers more information than views taken without the shoes. The image taken with the shoes on provides valuable information concerning the relationship of SD, palmar angle (PA) and digital breakover (DB) to the existing shoe. Knowing when the shoe was applied and having a working knowledge of farrier science and natural foot growth makes this information more valuable. A horse with a SD of only 6mm six weeks after being shod presents a completely different history from one with 6mm of SD that has been shod within the last six days or hours. Having this information might lead you to a better solution. Simply knowing that a horse has a very thin or bulging sole prior to pulling the shoe can save a ton of grief for the animal and greatly enhance your effort to help him as you know not to subject the horse to the trauma of standing on an x-ray block or walking around without the protective benefit of the shoe. Farriers who are familiar with the silhouette of the hoof and can interpret SD, PA and DB on the lateral and DP view with shoe on can use this information to better enhance the healing environment. These three parameters are what all farriers should be aware of before trimming the problem foot, fabricating a shoe and applying it. Using this information in an effective fashion requires time and experience working with film. Farriers must first learn to read the silhouette of the hoof, be dependant upon veterinarians to take the views most informative to them and understand the importance of knowing how the rasp, knife and shoe influence the overall health of the foot. This is a tremendous job for all of us, to say the least. There are views that offer more information when taken with the shoes off. All 65 degree DP views and the tangental or skyline views of the navicular bone should be made with the shoe off in order to avoid unnecessary scatter radiation and superimposition of the shoe over the subject. Cleaning the Foot When farriers are present it is best for them to clean the foot up. How well it needs to be cleaned up depends on the answers you seek. All mud and debris should be routinely removed from the hoof, sole and hair along the coronary band and pastern. This will suffice for most all lateral and DP scout views when assessing balance and soft tissue parameters that can relate to several soft tissue lesions. When navicular problems, fractures, keratomas or subtle bone remodeling are suspected, the foot should be cleaned of all irregular tags. Exfoliated sole and deep crevices often found in the base of the frog should be trimmed in a fashion to help clean the air pockets that are often interpreted as fractures of the navicular bone. Visualize all areas that will be superimposed over the subject area and you will know how well the foot must be cleaned up. Prepare the foot for the answers you seek. Using your x-ray unit to confirm your tentative diagnosis can help you tremendously as you search for a solution. Taking film for the sake of seeing what you can find is not always productive, as often times it sets us up for misinterpretation of pre-existing lesions that may not have any significance at the current time. Radiographs without a history and a physical exam have limited information relative to the state of health of the foot. Of course there are radiographic lesions that are pathognomonic for several syndromes, but there is also a great deal of information that lies in the shadows, that when coupled with the exam and history can help us assure a more accurate assessment and open the door to options that would otherwise not be available. How to Perform a Venogram The equipment used at IEPC is a 100/30 MinXray portable unit, asymmetric 6/12 screens, Fuji Super HR-U 30 and 3M Ultra Detail film and a 6:1, 106 line/inch grid. Several contrast mediums have been used in the past, however we have found that higher concentration produces slightly more information. Reno-60® has been the contrast of choice for the past several years. A variety of catheters have been used. The 21-gauge butterfly is easy to use, easily procured and provides a consistent means of delivering contrast. Sedation of the horse, local analgesia of the foot and a tourniquet placed over the fetlock is required. The original venogram technique developed at IEPC was a collaboration with Dr. Chris Pollitt using his previous in vitro study model and has since been published with minor modifications. 2 The imaging sequence that has been routinely used is soft tissue lateral, lateral with grid, DP with grid, DP with soft tissue detail, followed by a soft tissue lateral. The procedure is technique sensitive in large part because the sequence of film must be taken within a time frame of 45 seconds following contrast injection. Tissue contrast injected retrograde into the palmar vein is quickly absorbed into the interstitial space, significantly reducing the value of the information obtained. The soft tissue lateral images have proven to be especially valuable because they allow us to see coronary papillae, circumflex vessels, solar papillae and acute and chronic lamellar leakage. The grid used with the higher MAS has proven to be a reliable means of imaging the terminal arch and its tributaries. The soft tissue and hard penetration grid views were implemented to allow us to evaluate normal vascular anatomy and structural alterations within the soft tissues and bone. The soft DP view allows us to evaluate the medial and lateral coronary supply and the medial and lateral circumflex network. The grid view offers further information concerning the terminal arch and tributaries. The soft tissue lateral view taken at the end of the sequence was implemented to allow for adequate filling time required to consistently image lamellar leakage, decreasing the possibility of missing significant structural alterations. More specific beam selection is required to image vascular lesions associated with White Line Disease and Keratomas. Techniques for imaging the equine foot will continue to evolve with increasing experience performing venograms. Tourniquet failure and perivascular injections are frequent complications encountered in the infancy of procedural skill development. Both complications result in underperfusion and can lead to grossly inaccurate interpretation and misuse of the information. Technique underperfusion should not be confused with stark loss of contrast caused by pathological vascular compromise. The distinction should be well understood before deciding the fate of a laminitic horse based on the information gathered from this valuable tool. Technique 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 proper 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 prevent twisting of 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 to far in to 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 by unloading the deep digital flexor tendon (DDF) Clamp a hemostat on the catheter. Quickly tape the hemostat to the leg using the loose end of the tape that secures the tourniquet. Take your series of film. All exposures should be taken within 45 seconds. Move quickly. Radiographic Views Lateral, soft exposure Lateral, hard exposure with grid DP, hard exposure with grid DP, soft exposure Lateral, soft exposure Soft 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 films. Acute and chronic cases will exhibit similar patterns, yet there are distinct differences between the two. Using the digital system, you may elect to take a mid-range penetration. Bare in mind though, all units have constant adjustment limits. The goal is to see the smallest vessels, tubules and solar papillae as well as the terminal arch, which requires considerably higher MAS. Remove the tourniquet and place cotton or gauze over the medial and lateral vessels. Tape in place for 5-10 minutes.

Equus Magazine October 2004 Issue Below is an 8 page article discussing advances in amputation and prosthetic devices. These are viable alternatives to euthanasia when a horse's limb is damaged beyond repair. Dr. Redden's amputation cases are featured in this article entitled, "An Artificial Leg to Stand On", which appeared in the October 2004 issue of Equus magazine. This article and picture are used with permission from Equus magazine. Complete Article If the Complete Article pdf is too large, each page is available below. Page 56 Page 57 Page 58 Page 59 Page 60 Page 62 Page 64 Page 65

2004 - 17th Annual Bluegrass Laminitis Symposium Notes How To Make It Happen; Evaluation, Strategy, Planning and Execution Written and presented January 2004 by R.F. (Ric) Redden, DVM "Making It Happen" requires a farrier and a veterinarian to prepare themselves for the mission. Preparing for a professional career has an initial "crank up" period. Vets normally attend four years of college followed by four years of professional school. This intense period is very demanding and requires very serious discipline and dedication. Vet medicine is a much more complex field then most people understand. Simply staying current with new concepts and techniques requires constant continuing education. Vet school prepares its graduates with a reliable means of thinking as a vet with an emphasis on small animal, food animal, equine, exotics, regulatory medicine, research and others. This base is a tremendous asset for anyone wishing to excel in any of these fields. Unfortunately, equine podiatry is not one of the areas of intense focus, so it leaves a major black hole in our profession. One vet stated that he went to school four years and learned that the foot was a primary cause for most all leg problems. However, the professors never got around to teaching them how or why this was true nor what to do about it. Considering the intensity of the four-year program, it is no wonder there is not time to fit a single new subject into the curriculum. The best we can offer a vet student is an insight into the field of podiatry and the incentive to pursue this field after graduating. Becoming focused on foot problems requires horsemanship skills, farrier skills, a passion for exploring the unknown and an enthusiasm for new ideas. Preparation comes with a price, and there are no shortcuts to a successful career. Vets must learn their way around a foot much the same way farriers do; on the job training. Training, shoeing and shoe making become quite easy once we have learned all we need to know about the basic formula. Understanding simple body language requires months to learn and years to develop. Without it, though, the thought process is stifled when under a horse for a routine exam. Simply working with an accomplished farrier for several weeks is a great way for most vets to gain exposure to the basics, and develop the feel and insight required for the simplest routine exam. What we don't know is the kicker. This is where ego lives and efficiency doesn't exist. Farriers on the other hand have a similar dilemma. The large majority of farriers throughout the United States, Canada, and most of the world (except Europe, Scandinavia and Japan) are self-taught or work as an apprentice for someone who was self taught. This is not entirely bad, but the learning curve is vertical many years and can plateau anywhere along the way depending on one's goals, appetite for challenge, business sense and dedication to the horse. Most farrier schools start at ground zero and are measured in weeks of study, not months or years. At best, there is nothing more than a quick glance at farrier science. Clients have little knowledge about the foot as well. They are holding the shank waiting for their vet and farrier to get their horse's foot fixed with no clue of the education, experience or skill of either professional. Yes, one or both of them may have a great reputation in their respective profession, but how does this prepare them for the mission at hand? Extrapolating one's expertise from surgery, medicine, reproduction, small animal, etc. and applying it to the foot of the horse is high risk at best. Shoeing and trimming top athletes for 10-15 years certainly doesn't teach the discipline of podiatry either. Unfortunately, many times neither party has a grasp on the subject. Therefore, controversy grows, there is gross miscommunication, and one profession begins to blame the other. This dilemma will only get worst if we fail to recognize the seat of the problem. Education and training in the field of equine podiatry is the answer. From this point on, we must concentrate on how we can all become more knowledgeable and effective in the field of podiatry. Let's examine the foot, and for a moment leave the hoof testers and the Carbocaine in the truck. Simply look at each foot from all angles, noticing the body posture and conformation, as well as what the horse is telling you about how he feels about the exam. The message he gives about what is wrong with his feet is loud and clear. Each foot will give you either subtle or strong messages concerning the unhealthy areas. Compare foot-to-foot, front to back. Mentally split the foot, front to back and medial to lateral. Check all the normal healthy areas, remember them, and then remember the areas of concern. Don't jump to any conclusions at this point, even if you are convinced the horse has an abscess or whatever. Listen to the complaint and then the history. Try to keep it brief by asking only important questions. Most owners and trainers will not be aware of what is important and will carry you through the whole morning bending your ear. Pull the shoe if necessary or indicated. If it hides pathology grossly or radiographically, it should be removed. Always ask permission to remove a shoe, and be careful if the foot has marginal quality. You goal is to leave the foot in better shape than you found it. I also like to ask if there are any financial restraints before I begin, even if the owner pulls up in a Mercedes. This makes a tremendous difference - Note: financial restraints seriously handicap your exam, so point this out and put it in writing when you make your conclusions. Don't be suckered into doing a $500 exam for $100 with everyone expecting the same quality answers. It doesn't happen. Pulling shoes from a hunter is a bit different than pulling the shoes from a world champion walking horse. Therefore, veterinarians may want to have the regular farrier present during an exam to pull the shoes. In addition, information concerning the unique characteristics of the foot can be very valuable. Farriers, it is best for you to have the vet present when you pull the shoes, as many feet will be a wreck if left unshod for hours to days. This all-important meeting is a tough one. This meeting will only be successful if there is a strong desire to solve the problem. We must leave the "what is convenient for me" out of the equation and start thinking outside the box. How can we make it happen? We can only be successful if we approach exams like the last vet and farrier did; together. Quick, down and dirty talk is what drives the market, but it doesn't make it happen! Think of all the foot exams as routine and you will miss the majority of them. All are unique, and most all problems are relative to the overall health of the foot. Therefore, the basis of my exam is to look for all the healthy areas. What is left over is what you want to further explore, as that is where the problem lies. Seldom do we find simple primary diagnoses with the foot. Most every problem is multi-faceted, and each area involved must be dealt with mechanically or surgically. My goal for any and all foot problems is to simply enhance the healing environment. Mother Nature does the rest! The secrets of my thinking process begin with foot reading. A few points of interest: Mismatching hoof angles means one foot is a club foot. Which one is it?Mismatching heel-tubules angles means one is a club heel and one is a slam dunk heel. How well you understand this determines where you go from here.Always relate to the strong image of the foot with healthy soft tissue parameters. You can only learn this range from studying radiographic information on several hundred feet of horses of different breeds, age and use. This is part of the learning curve. Most vets can spend 10 years studying feet. You must be focused on every foot you examine and add this information to your data base each day. How much sole does your horse have? 5-10mm or 15-20 mm? Most all farriers know if the sole is thin, thick or okay. None can say with accuracy just how thick it is or how thin it is, nor can they describe with consistent accuracy the palmar angle without the benefit of radiographs. Therefore, to make it happen, the first step is to recognize the characteristics of the start model. Simply recognizing the fact that if the soft tissue message is a major part of the information, we need to consistently gather data and film from the examination. This means we need to develop a meaningful, consistent protocol for gathering information. When we achieve this, we begin to see all feet in the same fashion, and the data banks of what is healthy and what is pathology becomes more clear. Opening up a foot or pulling a handful of film from the processor with Forrest Gump philosophy will not make it happen. Fresh out of school, I surely felt that x-rays were like a box of chocolates; I never knew what I was going to find. This thought process severely limits our ability to think outside the box. I soon realized if I continued performing any lameness exams in the same fashion, I would expect to get the same results. I needed to know more, so I developed a disciplined radiographic protocol that allowed me to see every foot in exactly the same plane. I developed over 40 different positions that now allow me to meet the goals of the client, the financial restraints, the history and what I find clinically. I seldom use diagnostic blocking to determine what part of the foot is painful because I can perform a much more accurate assessment by looking at the areas that are no longer healthy. This is where pathology reigns; excluding puncture wounds and fractures. All other soft tissue problems that make up foot lameness can be easily read, and my radiographs serve as a confirmation of my findings. I hope I can show you how easy it is to focus on the areas that are glaring at you, and how to use the soft tissue parameters to Make It Happen!

Indepth Equine Podiatry Symposium Notes Written and presented January 2009 by R.F. (Ric) Redden, DVM This disease is caused by bacteria and fungus involving the stratum medium (the white zone) of the wall. Anatomists many years ago named the terminal laminae the "white line" which was a terrible misrepresentation and has caused much confusion. The terminal laminae are yellow to brown in color, never white, but lie on the inner border of the white zone, the non-pigmented portion of the hoof wall. There have been numerous fungi and bacteria cultured from horn defects and it appears geographic location is a determining factor. Fungi are opportunists looking for a place to grow. It is my opinion that a scar, defect or structural weakness is present prior to all fungi invasion of the horn. Treating a large number of white line disease cases over the last 30 years, I have found that 100% of all unilateral cases involve the club foot or high heel foot. Many times it is only a grade one to two club, which is seldom recognized as a club foot. But looking at the subtle differences in the two feet visually and radiographically reveals typical club foot characteristics. Examining the history on several cases revealed that the majority had an abscess break at the coronary band as weanlings or yearlings due to typical excessive toe wear found in club feet. Those that toe in will normally have a white line disease lesion along the anterior-lateral quarter. Those that toe out tend to have a white line disease lesion along the anterior/medial quarter. Diagnosing A clinical exam can be conclusive, especially in the advanced stage. The solar surface will be void of horn wall in the area of involvement. The sole migrates forward, pushing the terminal laminae forward and proximal. The only way the defect can be observed is by lifting the sole. Tapping on the wall can create a hollow sound. Radiographs clearly reveal the defect, but radiographic interpretation can be deceptive. Radiographic lesions characteristic of white line disease are similar but strikingly different from those found with laminitis. Both frequently encountered syndromes can have significant capsular rotation, a greater than normal palmar angle, very thin soles and a lucent submural lesion. Stark differences in shape and precise correlation of the lucent zone clearly distinguish white line disease from laminitis. White line disease involves the horn side of the horn-lamellar (HL) zone while laminitis involves the lamellar side. Bacteria and fungi invade the soft, non-pigmented (white zone) portion of the horn wall at the ground surface, apparently along small fissure lines, disrupted areas of horn or along existing scar tissue caused by previous toe cracks or abscesses that have migrated up the wall. The invading organism quickly destroys the integrity of inner horn wall and creates an irregular shaped air density lesion that is routinely evident at the ground surface and has irregular borders that are often superimposed over bone. Close examination often reveals dirt, sand and debris in the confines of the air space. The debris enters the void via the small opening formed by the sole that has grown forward. Lucent lesions due to laminitis and bone displacement occupy space that is created at the junction of horn and laminae as the coffin bone is pulled away from the lamellar horn attachment. The shape of the lucent zone is relative to the direction of bone displacement. Pure sinkers routinely start with extreme swelling of the L side of the HL zone before sinking. The lucent zone has a very uniform border that closely reveals the path the bone has taken. Cases that rotate or have a combination of rotation and sinking also leave a lucent trail that describes the path of displacement. The proximal limits of the lesion have a rounded border at the distal end never extends to the ground surface, but it is confined to the limit of the inner sole even when penetration has occurred. Clinical Signs The clinical signs of white line disease can also be very similar to laminitis as both can have an elevated pulse, extreme heat, a dropped sole (centered on the foot or off to one side) and are very sensitive to hoof testers. History The history remains one of the most significant parts of any examination, especially concerning syndromes with similar clinical signs. Most white line disease cases are often diagnosed when very significant damage has occurred, causing large air pockets and often extensive bone displacement. The typical case is a sport or speed horse that develops acute lameness following a race. Radiographs reveal tremendous damage in a horse that has just raced very successfully. This is the key. Laminitis cases do not present in this fashion. They are always lame several days to weeks before lucent lesions are radiographically demonstrable. Farriers often detect the presence of white line disease when shoeing the sound athlete. The wall may sound hollow when subjected to the action of the nipper, rasp or hammer. Close examination reveals a small slit at the toe in which a large shoeing nail or screw driver can easily be inserted. Treatment Example 1: The athlete that is suddenly lame. These cases are a bit more straight forward than the one that has a large defect but is currently sound. Acute pain is apparently caused by direct trauma to the sole and bone due to the loss of horn support, which allows sagging of the bone, significant compromise to the vascular supply and excessive pressure of bone against sole corium. Venograms closely reveal the compressive nature of the focal displacement. Treating the syndrome is much like the toe crack case. Significantly reducing DDF pull will immediately unload the internal load of bone against sole corium and aid prevention of further mechanical horn tearing along the upper margin of the defects. The decision to remove the horn is dependant on several factors. First, it is important to consider the immediate and long term goals of the client. As a rule the cases with extensive loss of horn integrity and acute lameness need to be immediately taken out of training. All undermined horn wall should be removed, the exposed horn thoroughly debrided and a rocker rail shoe applied in a fashion that creates a zero PA between the wings of PIII and the foot side of the shoe and a self-adjusting PA of 15-20 degree with the ground. Recovery can take several months and I do not put horses back in training until the lesion has completely grown out, the medial-lateral balance is once again acceptable and the sole depth is measured at 15-18mm. Systemic, anti-fungal medications can be helpful but used alone do not offer favorable results. Example 2: The sound horse with significant white line disease lesions. These cases present a totally different picture than the previous example. Farriers and vets frequently put themselves in a precarious position when making the decision to remove the wall and clean up the larger defects that are found with a routine check up, shoeing or even following a pre-purchase exam. Before removing the wall it is imperative that the responsible party is fully informed of the significance of the lesion, treatment options and the risk of continued training if the lesion is ignored. This very important conversation is always based over past experience with the disease and becomes a judgment call for all concerned. Rule of thumb that helps me predict the client’s interest is the health of the foot. If the lesion only extends up to the level of the apex of PIII, I clean up from the bottom, pack the defect with oakum, apply a rocker action shoe and treat daily with a topical antifungal agent. The horse stays in full work and I monitor the defect radiographically at every reset session. When the lucent zone extends only 5-10mm above the apex and the hoof wall and sole are reasonably strong and healthy I will treat basically the same. A small hole is drilled in the outer wall at the most proximal limit of the defect. White, chalky material is removed from the bottom with a very small curette and the areas are packed with oakum and treated daily with antifungal agents. The horse is taken out of full training. Strenuous exercise is put on hold and the lesion is monitored closely for the following 6-8 weeks for signs of advancing or migration up the wall. Preferably the horse is shod with a high mechanical shoe that promotes accelerated horn and sole growth and is compatible with breed specific conditioning exercise. When the lesion is half way up the face of PIII I recommend the horse be taken completely out of training to achieve a more successful outcome. When the client elects to go against my recommendation but requests that I try to patch the foot up for one more race or event I offer to do so but with a written note describing the risk involved and the fact that the client is fully accepting the responsibility of the risks. There are clients who can defy all common sense laws of Mother Nature and get a few more starts or shows out of a horse that should not be in training. Catastrophic injuries and fatal consequences for horse and rider have occurred as a result of such thinking. As professionals we are responsible for good advice and concern for not only the health of the foot, but for the rider as well. Soundness and the ability to race and show successfully is not always an indication of good health. This disease clearly points that out.

he answer to safer, easier IV’s Make a frozen popsicle using a 20 cc. or 35 cc. syringe casing, water and a tongue blade. Holding the popsicle to the jugular for 30 to 45 seconds will numb the area prior to the needle stick. You will be surprised how the most difficult ones will respond to this simple technique. Dr. Redden uses this technique on most all weanlings and yearlings as a training aid. They learn to overcome their fear of shots and those that are already very difficult to inject are immediately more receptive. This little tip can keep you in practice another ten years as it makes IV's so much easier and safer. The tough ones can get you.

2003 - 16th Annual Bluegrass Laminitis Symposium Notes How To Treat Club Feet And Closely Related Deep Flexor Contraction Written and presented January 2003 by R.F. (Ric) Redden, DVM Products for Club Feet Before we begin discussing how to treat any foot problem, we must first take a closer at the details of the respective foot. Many years ago, I found a need to develop a very simple classification system that would allow horseman, veterinarians and farriers to better communicate. Using the graded scale of 1-4 allows everyone involved to be on the same page when discussing a particular case. Club feet are the result of mechanical imbalances that are most likely attributed to malfunctions within the deep digital flexor muscle belly. The muscle fibers normally receive an electrical stimulus that tells them to contract. This causes the fibers to shorten and subsequently move load. Apparently the imbalance is a problem at the synopsis (nerves/muscle cell unit), which results in the muscle receiving a continuous command to contract. This spastic muscle transfers the constant shortening, or pulling, to the tendon that is firmly attached to the semi-lunar crest along the posterior palmar surface of the coffin bone. Shortening the distance from the origin to the insertion point pulls the coffin bone around its articular axis. In very soft footing, the laminae and hoof capsules move simultaneously with the flexion of the joint. Anything that changes the free flow action creates a resistance that is directly proportional to the forces at play. Basic ways to increase the counter forces placed on the muscle, tendon, bone, laminae and hoof wall network are: 1. Lower the palmar angle without decreasing the digital breakover. Lowering the heel in an effort to treat the high-heel club significantly increases the tension within the network. 2. Increase the length of digital breakover. Extend the toe using a shoe or composite also increases the forces within the network. 3. Lowering the heel and extending the toe tremendously increase the tension on all structures. Listed above are three basic treatment plans that are often used in an effort to minimize the high heel/no toe growth syndrome. The counter-pull mechanical plan can be effective on low grade clubs, however it can create a devastating sequence of events for the higher grades. This reinforces the reasons to have a meaningful scale. It allows us to customize each treatment plan to the specific demands of each case. The grading system for a club foot horse is quite simple, it is broken down into four categories. For individuals who have used it for several years, it can be broken down into twelve categories, grades -1, 1, +1; -2, 2, +2; etc. Note the diagrams below and basic guidelines that will help you quickly develop an eye for all four grades. The following text corresponds with the images above: Grade 1 -- The hoof angle is 3-5 degrees greater than the opposing foot and a characteristic fullness is present at the coronary band due to the partial luxation of P2 and P3. Grade 2 -- The hoof angle is 5-8 degrees greater than the opposing foot with growth rings wider at the toe. The heel will not touch the ground when trimmed to normal length. Grade 3 -- The anterior wall is dished and growth rings at the heel are twice as wide as the toe. Radiographically, P3 exhibits demineralization and lipping along the apex. Grade 4 -- The anterior hoof wall is heavily dished with an angle of 80 degrees or more. The coronary band is as high at the heel as at the toe while the sole is below the ground surface of the wall. Radiographically, P3 is rounded due to extensive demineralization, and rotation may be present. When discussing how and when to treat club feet in horses, we must also look at the age and intended use of the animal. Treatments tailored for the unique characteristics and demands of each foot often reap more successful outcomes. The club foot syndrome can be found in foals one month of age. The lower grades, 1 and 2, are the most common. The majority of cases reach four to five months of age before noticeable differences are detected. Newborn foals that have significant deep flexor contraction are often up on their toes or even knuckled over with the more severe contraction. Most cases respond in a favorable fashion using a variety of treatment methods; tetracycline, toe extensions (taped or glued on), splints, cast, snap on fiberglass splints, air splints and stall confinement can be used very successfully to treat the foal with a contracted tendon. Keep a record of foals with contracted tendons and you will find a large majority develop a club foot with a grade of 2 or higher by the time they are five months of age. Treating early stage club syndrome increases the odds of preserving bone integrity and the health of the soft tissue growth centers. Therefore, it is very important that all responsible parties develop an eye for the early changes that clearly describe a grade 1 club. The first noticeable difference is the pastern alignment. It is pushed forward and will appear in the same linear plane as the face of the hoof capsule. Stand back ten feet and look at the negative space that borders the face of the hoof and pastern. The normal foot will have a pastern that is set back slightly and still be parallel to the anterior face of the hoof. The toe angle will be 5 degrees steeper than the opposite. The angle depends on the breed, age and the unique characteristics of the individual. I disagree with much of today's literature that describes feet on young horses as having 60 degree hoof angles. It is obvious to me that individuals who subscribe to that opinion have never actually measured the toe angle on many foals. It is rare to find a foal with a hoof angle less than 63-65 degrees, regardless of the breed. This angle doesn't start dropping for several months unless aggressive trimming techniques are used to remove the strong heel that is found on most foals. Looking closely at the sole surface of a club foot, the bars are beginning to turn inward at the heel and many times touch the frog. Compared to the opposite heel, there are stark differences in angles of the quarters. The heel tubules are slightly tighter with as much as 5-10 degrees difference. Using close up photography, with the projection angle perpendicular to the surface of the foot, you can train your eye to notice the subtle details. Treating the Club Foot, Grade 1 I like to push the heel back to solid, strong heel starting at the center of the frog area. I then rocker the toe forward from the same point leaving the center of the foot as a noticeable pivot point. Leave the frog and sole and put a smooth, but non-invasive, radius on the ground surface horn. This method promotes the flow of nutrients to the sole, which accelerates sole proliferation. This, in turn, protects the very soft and vulnerable palmar surface at the apex. Enhancing sole growth also stimulates anterior horn growth. This effect is the direct result of significantly reducing the tension on the deep digital flexor tendon by pushing capsular breakover to the middle of the foot. The tendon is not opposed by forces at the toe, therefore a lifting effect occurs within the capsule. This phenomenon can be clearly demonstrated with venograms. Re-examine the foot in ten days, if the heel and toe growth rate appear to be equal stay with this very simple, but yet effective, method. Trim the foot every two weeks to maintain the mechanical advantage necessary to offer equal toe and heel growth. Some grade 1 feet will remain as such for the duration of the horse's life without any treatment whatsoever. Others will proceed up the ladder to the higher grades; some very rapidly, others taking many months to reach the higher grades. At the onset, it is difficult to know which one will have a stronger tendency to continue contracting. Treating all of them very early certainly sorts this out very quickly. For many years, traditional methods have been prescribed for club feet as a whole (no grades considered). These methods focus on making the foot appear as if the club immediately went away. Using a good sharp rasp and a little imagination anyone can take enough foot away to make the remaining stump appear as if it never was clubby. The club is the same as it was before with one exception; the foot has far less natural horn protection, and the deep digital flexor load has been significantly increased rather than decreased. Increasing the tension on the deep digital flexor as it attaches to the coffin bone, laminae and horn network by excessive sculpturing can and often causes permanent bone damage due to simple internal download. The result shuts down the fimbriae that grow the sole, it compress the circumflex vessels tightly between the palmar surface of the bone and wall, it shuts down tubule production at the toe and enhances tubule growth at the heel. Ten days later, the heel growth exceeds toe growth, a slight dish forms at the toe and there is less sole than when the foot was trimmed and shod. Farriers that use the older, more traditional method designed to stretch the muscle and tendon need to be very aware of the case that doesn't stretch. Continued application of the stretch mechanics creates a thinner sole, more horn growth at the heel, and it can be cause permanent bone damage. Treating the Club Foot, Grade 2 & 3 Grade 2 club feet have very distinct changes that can easily be seen. For example, the heel growth pattern is twice as wide as the toe. When asked to stand with the toe of the club foot slightly behind the heel of the opposite foot, an air space will be present under the heel. Try passing a piece of paper under the heel, as the space is difficult to detect unless your eye is at ground level. A Grade 3 club foot will have basically the same characteristics. The growth at the heel may exceed the toe growth three or even four to one. The anterior face of the hoof capsule will have a distinct dish, which is the result of excessive internal down loading created by the resistance of the toe against the unrelenting pull of the deep digital flexor tendon. Successful treatment is dependent on the ability to adequately disrupt the pull of the deep digital flexor tendon. A set of soft tissue, pure lateral radiographs with wall and ground markers provides the information needed to better evaluate the sole depth, palmar angle, horn-lamellar zone, bone shape and load induced changes. Using the traditional stretching concept for grade 2 and grade 3 clubs places tremendous internal load on the soft, fragile apex. This triggers a cascading sequence of events. The bone actually begins to bend at the lower third, much the same way hoof capsules does for the same reason. The sole is also compressed, strangulating the nutrient supply to the solar plexus. This, in turn, stops sole growth. The next stage is bone re-absorption, which is often accelerated by the presence of soft tissue sepsis due to excessive wear and abscesses at the toe. Once the dished apex appears rounded off with roughened borders, the prognosis for athletic performance is significantly decreased. Therefore, it is critical that you make every effort to prevent the second stage fallout. Using the radiographs as a blueprint, we can design the mechanics indicated on the film. I like to draw a line parallel to, and 15-18mm below, the palmar surface of PIII. The line becomes the trim line. Often times, the toe is quite thin so little if any can be removed. I fabricate an aluminum shoe with a rocker rail, (note diagram) and apply it with Equilox. The belly of the shoe allows self-adjustment of the palmar angle, which relieves the pull on the deep digital flexor tendon. Subsequently, the blood flow to the deprived area of the sole and bone is enhanced. These cases often show a significant measurable increase in sole depth and anterior horn growth within three weeks post shoeing. Reset in the same fashion until favorable results are obtained. Favorable results are even growth ring patterns, the trimmed heel can load evenly when placed behind the opposite foot, and sole depth can easily be maintained at 15+mm. Those that fail to show a favorable response are considered for surgery. When To Cut the Check Ligament First, I ask the client what his/her goals are. Next, I explain that all inferior check desmotomy surgeries leave a noticeable and palpable scar. Many surgical sites are only slightly blemished, others can be very unsightly for no apparent good reason. Nevertheless, these scars are to be expected. The benefits must always outweigh the disadvantages when making the decision to perform surgery. The athlete's ability is rarely threatened with this surgical approach, but complications can arise that diminish the positive aspects of the procedure. Shoeing Prior to Surgery I have seen numerous cases that had the check ligament cut and nothing done to realign the natural load zones of PIII. Consequently, the check healed back at the same length and the foot remained the same. Cutting the check is a simple mechanical procedure designed to diminish the pull of the deep digital flexor tendon. Cutting it certainly accomplishes this goal, but failing to realign the palmar angle does little or nothing to improve the foot. The palmar angle is trapped in a permanent position with the semi rigid horn capsule. To gain optimum results one must allow the foot to quickly remodel around the readjusted palmar angle as the check is healing. The surgical gap is only present for a few weeks at best and soon becomes a permanent scar, which has little or no ability to be stretched. Getting the optimum stretch just prior to surgery compliments the surgery. Using the lateral radiographs as a shoeing guide, draw a line parallel to the palmar surface and 18-20mm below the wings of PIII. This is the position of the shoe once the foot is trimmed. Extend this line forward until it bisects a line drawn from the most proximal horn wall to the toe area creating a 50-52 degree imaginary toe angle. Feet that have been previously trimmed every ten days to two weeks will have very little, if any, heel to remove, but the shoe must set in the prescribed position in order to gain optimum stretch or gap once the check is cut. The zero palmar angle and 50-52 degree actual toe angle will be bit overkill, but years of experience with a large number of cases has taught me not to be conservative with higher grades as they have a tendency to drift back to the club syndrome given any chance at all. To apply the pre-surgical shoe, use a rasp to roughen the wall at the heels. Push the heel back creating a flat zone parallel to the palmar surface as described. Caution: Learn the landmarks that help you go from film to foot. The common error is to remove far too much foot in an effort to set the shoe on the toe. This creates positive palmar angles and severely compromises the circumflex network. Clean the toe area well. Look for splits in the sole wall junction that may be harboring potentially harmful bacteria. To be assured that you don't seal up these potentially hot areas with Equilox, use a small amount of Keratex Putty to protect them from the composite. I cannot over stress this step; abscesses under Equilox can be extremely painful and cause irreversible damage to the bone, as well as growth centers. Normally I use an aluminum queens plate shoe shaped much like a mule foot. This shoe is actually propped up at the toe. The Equilox fills the gap between the shoe and sole. Sole pressure is not a concern once the check is cut as the download is significantly reduced. This prevents the majority of internal compression. The foal must be sedated and the foot surface cleaned well prior to applying the Equilox. Once it is applied, hold the foot up until the Equilox has cured. In cold weather, warming the shoe and Equilox will speed up set time. Apply the support aid: Once the shoe is on, I don't allow the foot to be loaded until I have applied a large wedge of Advance Cushion Support to the bottom of the shoe. This wedge must be thick enough at the heel to replace the original palmar angle in relation to the ground. Setting the foot down without this large wedge puts tremendous load on the laminae, apex and sole simply due to the increased lever action of the toe extension and zero palmar angle. Once this wedge has been applied, the foal is ready for surgery. The procedure can be performed immediately or even days later, as the sensitive structures of the foot are well protected with the rubber wedge. Surgery - Inferior Check Desmotomy I prefer to cut most checks using local anesthesia, blocking above the knee, and a light sedation (Dormosedan .2 - .25 cc.) for most large foals. The elevated heel reduces the load on the deep digital flexor tendon, making it relatively easy to slide a retractor under the insertion of the check as it fuses with the deep. This junction is more distal than one would think and is not readily visible. Dissect with a pair of Metzenbaum scissors. A good thorough review of a post mortem limb prior to your first attempt is very helpful. I make a small incision (1-1.5 inches) just proximal to the anastigmatic branch. The lower incision makes it much easier to bandage, and it offers better cosmetic appearance because there is little or no muscle fiber in the insertion area. I leave the raised heel wedge on for a couple of hours following the surgery. This allows the foal to recover from general or local anesthesia without causing unwarranted stretch to the support ligaments, joint capsule and realigned joint surfaces. When the surgery is performed with the foal standing, I want the foal to have normal sensitivity in the foot before removing any portion of the wedge. Low grade clubs are not a big concern, but the higher grades the heel needs to be lowered gradually; this could take hours or days depending on the case. When removing the wedge, trim about one third of the rubber wedge off, re-tape and observe the foal for excessive soreness. If they are the least bit sore, wean the wedge down slowly. Twenty-four to 48 hours is normally all it takes. Slamming the heel down immediately following surgery can cause very serious damage to the support structures within the foot. Take a look at the pre and post op film. Note the close proximity of the navicular bone as it relates to the proximal, posterior border of PII. If the supporting apparatus of the navicular bone is part of the syndrome, stretching the area during recovery from anesthesia while the foot remains blocked can damage the navicular ligaments, navicular bone and impar ligaments. Post-op Care I normally confine the patient to stall rest on firm footing (no deep bedding) for 30 days. Afterwards, I graduate to a one acre paddock. Reset the shoe every 30 days using soft tissue detail, pure lateral film as a guide. I prescribe a prophylactic dose of broad-spectrum antibiotics for seven to ten days, and I bandage the leg with a very firm combine bandage. This bandage should be changed every seven to ten days for a period of 60-90 days. The longer the bandage is left in place, the less edema occurs. Over the course of 90 days, the bandage can be weaned off and normal turn-out exercise is resumed. Complications Less than optimum results can be obtained with any surgical procedure. A few commonly found problems include: 1. Failure to adequately realign the palmar surface of PIII. Omitting this step prevents a surgical gap in the check ligament following surgery, and therefore offers little, if any, relief to the growth center of the foot. 2. Failure to dissect the entire check ligament, especially when cutting high. The check is very thick and soft due to muscle fibers. It is easily split when gathering the entire check belly with a retractor. The check is crescent shaped and wrapped around the deep in the higher surgical approach area. Once it is split with the retractor or partially dissected, the remaining portion is difficult to locate due to its close proximity to the medial vessels and nerves. 3. Cutting the muscle fibers. Cutting these fibers promotes normal serum leakage, which adds to the scar. It can also foster an environment for post-op blood clots that can cause weeks of serum leakage and unsightly scars. Treating the Club Foot, Grade 4 This is a totally different situation than the lower grades, simply due to the degree of mechanical imbalance. The heel is higher than the top of the coronary band and most have a tremendous dish in the hoof wall. They also have a 15-40 degree palmar angle, excessive heel growth, little if any toe growth and advanced bone disease. Using the prescribed treatment for any of the lower grade clubs previously described, including the check desmotomy following re-alignment shoeing, offers little if any relief for the grade 4 clubs. I prefer to shoe these cases in precisely the same manner described above, but I elect to cut the deep digital flexor tendon mid cannon. This offers several advantages over the more conservative check surgery. There is little, if any resistance opposing the flexion of the coffin joint, which offers maximum relief to the internal structures of the foot. It is quite an easy procedure to perform on the standing horse using location anesthetic and sedation. Cutting the deep digital flexor also offers much better cosmetic appearance than the check desmotomy. Athletic ability doesn't appear to be threatened by early, successfully managed tenotomies. I have had horses perform at top level in many sports, with the exception of racing. Complications Due to the severity of the contraction syndrome, the support ligaments of the navicular can be part of the pathological process. The re-alignment process drastically changes the palmar angle, increases the forces on the impar ligament, navicular bone and supporting ligaments of the navicular bone when these structures are part of the syndrome. Allowing the horse to bear weight while blocked can literally pull the navicular bone away from its attachment to PIII. This can create a catastrophic avulsion fracture through the body of the navicular bone and/or rupture the suspensory ligament rendering the horse crippled. Slow and gradual removal of the rubber heel wedge tremendously decreases the risk of such post-op complications. Deep Flexor Contraction This syndrome is similar yet strikingly different than the club syndrome. It is more explosive in nature and can escalate to extreme contracture in a matter of days. The club syndrome, on the other hand, is much more gradual and may require months to reach the higher grades. Fortunately, most cases never even proceed above grade 2. The hoof capsule and bone characteristics are also strikingly different. The club foot develops a dish and bends the face of PIII creating a lip at the apex due to the relentless pull of the deep as it slowly pushes the heel upward onto the toe. Deep flexor contraction feet have a bull nose hoof capsule (bent back), and the coffin bone has a similar shape. The apex is turned back under the bone resembling the shape of a hawk's beak. The horn-lamellar zone will be much smaller at the apex than the more proximal one due to the forces at play and explosive nature of the syndrome. The contraction phase is very short, and the the heel and palmar angles can increase up to 45 degrees in a matter of days or weeks. Treatment Re-alignment as previously described and a mid-cannon deep flexor tenotomy (see video below) is my preference for all deep flexor contraction cases. The prognosis is quite good for slow sport, athletic soundness provided post-op management meets the demands of normal tendon repair.

Bluegrass Laminitis Symposium Notes Interpreting Venograms: Normal or Abnormal And Artifacts That May Be Misinterpreted. Written and presented January 2004 by Amy Rucker, DVM (Watch the Digital Venogram video performed by Amy Rucker, DVM.) Objective Becoming familiar with the range of normal venograms is difficult, but it is more difficult to become accustomed to artifacts that are induced by incorrect techniques. This presentation will attempt to discuss interpreting changes present on venograms. We will also review common findings of the pathologic foot. Consistency in procedure is the key to quality venograms! Changes in procedure usually result in artifacts or poor quality venograms. If you do every venogram the same way every time, you will gain a large amount of information. More importantly, following a consistent procedure allows you to compare venograms in order to assess progress or lack of progress resulting from your treatment. Normal Variations Because heel perfusion results from multiple sources and is palmar in origin, pathologic conditions of the foot seldom affect the appearance of heel vasculature. However, lateral radiographs will show compromised blood flow to a normal heel loaded by wedge pads. Raising the heel ten degrees significantly reduces the vascular fill in the palmar vessels and compresses the frog and sole papillae. The circumflex vessels, dorsal lamellae, coronary plexus, and terminal arch appear normal when a normal foot is elevated with heel wedge pads. Medial/lateral imbalance of the foot is apparent on the DP view. Horses with a jammed (proximally displaced) medial coronary band often have reduced fill on the medial coronary plexus when compared to the lateral plexus. This effect is exaggerated when a foot is wedged medially or laterally. Papillae extending into the solar corium are often not evident on a thin-soled horse. Although this horse may not be lame, the lack of sole depth and blood supply is far from ideal. The same phenomena is occasionally seen when a foot is bruised or compressed internally; Saddlebreds or Tennessee Walking Horses may have inches of sole and pad between P3 and the ground surface yet still be sore footed. Artifacts Perivascular contrast medium is the most common artifact we induce. Contrast can escape into the extravascular space if the vein is punctured multiple times during catheterization, the horse moves during the process, or the catheter comes out of the vein. A large pool of contrast media is evident on both the lateral and DP views at the level of the catheter in the palmar digital vein. The amount of leaked contrast must be taken into consideration as it may result in inadequate fill of the foot. Inadequate volume of contrast medium results from perivascular leakage, syringes coming loose from catheters, loosened catheter clamps or incorrect calculations in volume needed for the venogram. A four-inch foot will fill with 20ml of contrast; 5.5 inch feet require 24ml. A seven-inch foot will hold 40ml of contrast. Inadequate volume can be confused with poor perfusion. A characteristic narrowing of the blood vessels and lack of perfusion of the heel indicate that volume is the problem. Vessels have a "tree limb" appearance, becoming narrow in the distal aspect of the foot. A loose tourniquet will also cause an inadequate volume appearance. Radiographs will reveal contrast proximal to the tourniquet. Keys to placing a tourniquet include protecting the skin at the fetlock with Elastikon®, yet not using too much Elastikon® to pad the vessels beneath the tourniquet. Excess time to inject the contrast media and take radiographs will result in contrast media "leaking" into the corium and dermis. A fuzzy appearance at the margins of the circumflex vessels and dorsal laminae results if it takes more than 30 seconds to radiograph the foot. This artifact can be confused with leakage into chronic scar tissue. It is imperative that you time your venogram to distinguish between the two. A fully loaded foot with a long toe may not have fill in the dorsal laminae if the knee is not bumped to disengage the deep flexor tendon while injecting the second syringe of contrast. This artifact is difficult to induce in the healthy foot, but easy to induce in the laminitic foot. Venograms of the Pathologic Foot Reduction in vessel fill on venograms results from various conditions: I believe compression of vasculature by mechanical forces is the most important cause. When you review the vascular supply of the foot, it is apparent that all areas receive perfusion from at least two sources. However, rotation of the coffin bone within the hoof capsule will routinely cause compression of the circumflex vessels as the palmar surface of P3 moves distally. If the rotation is more significant, the margin of P3 moves past the circumflex vessels, compressing them between the wall and dorsal surface of P3. The coronary plexus will also be compressed by the extensor process dorsally and the ungual cartilages medially and laterally. Decreased fill in the dorsal laminae may be evident. The solar venous plexus may also be mechanically compressed, however the heels rarely appear affected unless the entire coffin bone sinks distally. When the coffin bone sinks, perfusion is reduced by mechanical compression, mechanical tearing of the tissue and vasculature, increased interstitial fluid pressure and edema, and vascular stasis. Increased sympathetic tone, vascular spasm, and arterial embolization will also reduce fill on a venogram. The Clubfoot Acute "Clubfeet" caused by deep digital flexural contracture may not have associated abnormalities of perfusion. If the condition were untreated, decreased perfusion at the tip of P3 would result. Clubfeet that develop over time have a dished dorsal wall and remodeling or lysis of the tip of P3. The dorsal laminae at the distal aspect of P3 will have reduced fill, as will the circumflex vessels. Acute Laminitis with Mild Rotation of P3 Initially you will see mild compression of the circumflex vessels, or rotation of the tip of P3 past the circumflex vessels. This is a common presentation among the chronic mild grass founders of Missouri. These horses often respond well to conservative treatment, only to repeatedly have flare-ups, because the initial damage never healed. If changes are mild enough, the circumflex vessels will remodel around the apex of P3 as the laminitis becomes chronic. Acute Laminitis With Moderate Rotation of P3 Compression may be evident in the circumflex vessels and the coronary plexus with reduction in fill of the dorsal laminae. If the coffin bone rotates quickly, a space is created between the dorsal wall and the dorsal aspect of P3, where the laminae are torn from the epidermis. The space is wedge-shaped, narrow at the top, and does not penetrate the sole. Contrast media will pool in this space. Chronic Laminitis With Rotation of P3 There are many variations of chronic laminitis. Remodeling of P3 may include mild lipping, or lysis of the tip until the bone is eroded through the terminal arch. Vascular changes also vary from mild to severe depending on the case. Characteristic of chronic scar tissue is a "feathering" appearance of contrast media into the dorsal lamellar scar tissue. The feathering occurs in the same area as the space seen with acute rotation, however the perimeters of the area are not defined and the contrast appears to feather into the tissue instead of pooling into the space. The circumflex vessels may be flipped up proximal to P3, or may attempt to remodel around the tip of P3. The dermal papillae may be irregular in orientation at the tip of P3, and may be exaggerated at the coronet where the dorsal hoof wall is thickened as the capsule is distorted. Rotation of P3 with Penetration of the Sole Any of the above mentioned changes might be evident. In addition, no vasculature is present distal to the tip of P3. When performing venograms on this foot, it is common to have a sticky, serous fluid leak from the penetrated area onto the radiograph block. Sinkers Sinkers may be difficult to identify. On lateral soft tissue radiographs, evaluate the distance of the extensor process from the level of the coronary band; compare front and hind feet. A foot that is sinking will have a Horn-Lamellar zone that is 20mm or greater, and the sole depth will be less than that of the other feet. A "halo" may be evident at the coronary band as the proximal and distal borders of the coronet become apparent. The DP view may reveal a foot that is sinking uniformly, or listing to one side. Venograms must be taken at light techniques to catch all the detail of the compressed vessels. The coffin bone of a sinker has fallen past the circumflex vessels, which are trapped at the periphery of the coffin bone and may not be evident. The palmar angle may approach zero, and the solar vessels will be crushed. The dorsal lamellar vessels will be compromised, and a rectangular pooling may be evident. The coronary plexus at the extensor process is not perfused, and may have reduced fill on the DP view at the medial and lateral aspects of the coronary band. Mild sinkers will have reduced distal perfusion on the DP view, but proximal compromise does not occur until several weeks of loading the coronet has compressed these vessels. Severe sinkers have reduced perfusion in the terminal arch and even the heel. Unstable Feet Previously I would take four views with my venograms: a standing lateral, elevated heel lateral, elevated heel DP, and a standing DP. If a foot is unstable, movement of P3 within the hoof capsule is evident: the HL zone may change, and a reduction in perfusion of the dorsal laminae may be evident. Most cases of laminitis have an increase in perfusion of the circumflex vessels and the solar and frog corium when the heel is elevated. Redden cautions against standing an acute laminitic, unstable foot flat on the ground, even for the few minutes it takes to perform radiographs or venograms. During that time the horse usually appears uncomfortable; if the horse is blocked and then stood flat, the horse is usually very lame when the block wears off. Enlightened podiatrists disengage the deep flexor tendon during the initial exam, and never let it pull at the laminae until the foot has healed. I now routinely radiograph horses in Modified Ultimate shoes, or remove their platinos and place them in the Modified Ultimates for radiographs and venograms. Note that the Ultimates will displace the radiograph cassette slightly from the hoof wall, and cause a small amount of magnification. Consider this when comparing previous radiographs without the Ultimates. If you have a laminitic horse that has recovered nicely and you are unsure if the feet have healed, you may try comparing flat and elevated heel venograms. Do not try this unless the horse has been sound for several weeks and all radiographic parameters have returned to normal. The flat venogram should be comparable to the elevated heel venogram with the only exception being a decrease in fill in the digital cushion area. Any other changes would indicate instability in the foot. Information in these presentations has been gathered from the "Valiant Project", which has received generous support from the following: Kim Abernathy, Betsy Arthur, Sarah Bailey, Shannon Baker, Mike Balke, Stacie Boes, Josh Bolte, Manda Boos, Kristin Campbell, Bobby Colley, Nick Coston, Kyle Creech, David Cross, Kellie Daly, Jenn Demko, Treena DeVault, Chris Downs, Elaine Dziuban, Tom Goss, Kelly Grabeel, Marcy Hammerle, Kevin Hatten, Brad Hill, Mark Hope, Laura Koenigsdorf, Raelynn Kemp, John Kreeger, Therese Kreutzberg, Kurt Kreutzer, Alison LaCarrubba, Jimmy Lattimer, Dean Morgan, Mark Mosbacher, Chris Nord, Shannon Reed, Margret Rogers, Beth Smith, Lisa Stephens, Keith Taraba, and David Wilson. Thank you! References Lyle, B.E. The Digital Venogram: Interpretation and Suggested Implications for Therapy in the Laminitic Horse. Proceedings Bluegrass Laminitis Symposium 2001. Redden, R.F. Classifying Laminitic Damage: How Using a Simple Scale Can Help All Concerned Understand and Project the Aggressiveness Needed, the Length, Cost and Future Outcome for What Lies Ahead. Proceedings Bluegrass Laminitis Symposium 2001. Redden, R.F. Equine Podiatry 101 Short Course. 2001.

2002 - 15th Annual Bluegrass Laminitis Symposium Notes Classifying Laminitic Damage: How Using a Simple Scale Can Help All Concerned Understand and Project the Aggressiveness Needed, the Length, Cost and Future Outcome For What Lies Ahead Written and presented January 2002 by R.F. (Ric) Redden, DVM Laminitis is one of the most complex disease syndromes facing the veterinarian and farrier. The disease is extremely complex and not well understood. And to compound the problem, the foot is actually a very poorly understood piece of the equine anatomy. The last couple decades have certainly changed the concept of "no foot - no horse" with the modern day horseman and professional. Advanced technology, current research and numerous articles concerning the foot have also fostered new concepts and ultimately a whole new mindset. Laminitis has traveled the same road. There have been tremendous advancements and increased knowledge about the syndrome; but unfortunately, even with all that is offered today in the prevention and treatment of the disease, little effort has been spent on classifying the degree of damage. I learned many years ago that seldom, if ever, do two horses have the same degree of damage. Likewise, feet are rarely affected the same on each horse even when the same mechanics and therapeutic regime are used. Several factors seem to influence the overall assessment as well as the progress rate and overall outcome. Just simply designing a detailed plan that adequately reverses the forces at play is all but a shot in the dark without first assessing the damage and identifying the precise areas compromised. Being able to grossly and radiographically assess the overall health of the digit requires a good working knowledge of the vast range of norm for all major breeds of horses. Training your eye to recognize the norm is quite simple if a rigid, methodical x-ray protocol is used for all radiographic exams. Picking lesions from x-rays that just might be the problem has inherent risk that often lead to misdiagnosis. Putting too much focus on the "abnormal" lesion can easily overshadow the benefit of observing the whole picture. The first mission in treating the foot is to develop an eye for foot characteristics. Become familiar with all sizes and shapes of feet that are breed specific. See them and feel them in three dimensions. The farrier has a tremendous advantage over the veterinarian from this perspective simply because they handle literally hundreds and thousands of feet annually. They soon develop the feel for what they normally see and begin to see what they normally feel. Conversely, most farriers do not have the knowledge and experience to interpret radiographic information. The result is that they often fail to manipulate the digit to gain maximum mechanical advantage for addressing hot spots, creating an optimal healing environment and reperfusing the digit. Veterinarians on the other hand have the academics, but only a few have the opportunity and time to develop a sense of feel for the normal foot. Therefore, it becomes difficult to relate radiographic lesions to the hoof capsule. Veterinarians and farriers who want to be podiatrists must learn to fully assess the foot internally as well as grossly. Without a working range of normal, subtle changes in soft-tissue parameters, as well as bone lesions, are meaningless. Mark Twain once advised that a riverboat pilot must learn more than is allowed for one man to know. Furthermore, he noted that to be a good riverboat pilot, one must learn everything he knows in another fashion every 24 hours. Watching for tree snags in an attempt to avoid sinking demanded unprecedented alertness on the part of all steamboat pilots. This holds true for the podiatrist, as every case is a challenge that demands a constant search for perfection. Lets assume that the range of norm is not an issue at this point, and we can go on to discover the slight variance of "normal" that are a reflection of the degree of damage to a given foot. Overall hoof conformation now plays a major factor. For example, Standardbreds, Morgans and some Arabs have a tremendous horn capsule. They have thick, heavy walls and dense, concave soles with lots of mass. Typical feet may have the following characteristics: Hoof Angle 53-56 degrees Heel Tubule Angle 45-50 degrees Sole Depth 20mm with a 10 mm cup Palmar Angle positive 3-5 degrees Digital Breakover 23mm Picture this foot. Draw it. Look for it. Memorize it. This is a strong, healthy foot given that all other intricate pieces of anatomy are normal. This foot can withstand a very significant insult to the laminae and still retain a normal foot given some sort of adequate treatment and a few months to heal. Let's look at another totally different type foot. This is a Thoroughbred weighing 1,000 pounds, race fit with the following characteristics: Sole Depth 1mm or less with no cup Palmar Angle negative 2 degrees Hoof Angle 40-45 degrees Heel Tubule Angle 15 - 20 degrees heel tubule angle CE 15 mm below the coronary groove This particular case also experienced a chronic toe crack, as well as a few migrating abscesses, when he was young. He has paper-thin walls that have been backed up into the white zone at the toe. This horse has a flat tire on a good day. Give him a little dose of laminitis and you have a total disaster. Determining the degree of damage to each respective foot is where a grading scale comes into play. My scale is very arbitrary, and I do not use it to come up with a specific number. Instead, I determine a range of damage based on several observable factors. It is nearly impossible to successfully treat a large range of damage without first determining how much damage is present and what you have to work with. Previous pathology or extensive stress on a foot also reduces the overall resistance of the digit. This makes it a high-risk case. In my book, Understanding Laminitis, I have the following basic scale: The 1 – 1000 scale could just as easily be 1 – 10 or 1 – 100, the significance of the 1000 scale is it emphasizes the large range of damage that can be found between, breeds, individuals and even feet on the same horse. The scale is there to develop a new mindset about how we talk about this complex disease syndrome. Having a much better feeling for the degree of damage, chronicity of the same and the sequence of cascading event that plague most all significant insult cases offers tremendous advantages for the veterinarian – farrier team that others are not afforded. When your working protocol is designed to attack the high scale cases then you have a plan. The failure to consider the large range of damage has brought bloodshed among farrier and veterinarians as they attempt to argue mute points concerning two totally different problems. If we are to speak about the success of a particular mechanical treatment we must not only identify the start model but also the degree of damage and specific areas of most damage. Zones of Concern The proverbial degree of rotation can be used as a perimeter indicator so long as we don’t get too carried away. I seldom if ever attempt to measure the degree of capsular rotation as it is a bit meaningless and quite arbitrary. There are not many feet with perfectly straight walls from the coronary ground to toe and none with a straight faced coffin bone. Draw your lines wherever you like, it doesn’t matter, you can easily see if there is 5 – 10 or 15 degrees, being more specific is a waste of time as it is not the damage along the anterior face of PIII that creates the major problem. For many years we have been taught that rasping the rotation away is a helpful adjunct to treatment. I don’t believe it and find no validity in removing the angle of capsular rotation. This is erroneously considered derotation and has no bearing on the outcome of the case other than to weaken the anterior arch of horn. But for the sake of describing perimeter variations we will use the broad brackets of 5 – 10 – 15 degrees as a means to describe rotation in the active rotating cases (not chronic, long term cases). Sinking We must be careful describing degree of sinking. Degree of sinking is relative compared to what? The distance between the top of the horn wall and top of extensor process varies greatly among horses. I find only the strong, upright foot to consistently have the extensor process quite close to the same plane as the top of the horn wall. Weaker, flatter feet with numerous types of pathology can be as much as 20 mm. below the horn wall and survive as quite sound animals. Therefore unless the extensor process is at the level of the horn wall on the first radiographic examination the significance of it being lower may have little validity if it has been there for some time. Regardless, marking the hoof wall with radiopaste points starting at the hard horn of the coronary band produces a very distinct marker for tracking the descending coffin bone, especially sinkers. I look for no sinking, 5 mm, 10 mm, 15 mm, and 20mm; this is actual movement from the start point not a one time assessment without prior knowledge of the norm for that individual. Sole depth is measured straight beneath PIII to the top surface of the shoe or ground marker on the barefoot horse; be as accurate as possible within one millimeter when possible. Make certain the primary beam is centered close to the palmar surface of PIII in order to accurately measure sole depth and palmar angle. It is the sole beneath the wing that is measured not a sagittal cut. Performance Thoroughbreds and Quarter Horses often are found with less than 10 mm. of sole, not that they are sound but they often remain competitive. They can go to 3 – 5 mm. and seem to survive it where a horse with 15 to 20 mm. compressed to 3 to 4 mm.is in serious jeopardy. Laminitic Warmbloods with 20 – 2 5 mm. of sole compressed to 15 mm. are seriously compromised and soon develop to high scale damage, therefore the start point is once again part of the assessment. Considering the sole depth with extensor process measurement can be helpful with comparative film when there is little sole, less than ten degrees and no change at the top, I call this the Belotta syndrome. The foot has been rasped off, sole thinned since the last film was made. The palmar distance looks like a sinker but the perimeter at the top has not changed. This is a very significant finding on a bilaterally lame horse that look very laminitic, e.g., can’t walk, and front feet out front, throbbing pulse, painful to testers or even thumb pressure, horn – lamellar zone normal, extensor process 5 – 10 below horn wall, 5 - mm. of sole – guess what? No foot, simply trimmed inside the comfort zone. Put them on thin soles then try to cup it out on barefoot horses and you have a sore baby that can take weeks to heal. Palmar Angle is measured by drawing a line along the wings of the palmar surface (not the toe area of the apex) as it relates to the ground surface. We also speak of it as it relates to the heel zone of the shoe. Several factors influence palmar angles: Club feet naturally have a much higher palmar angle than the opposite which can have a negative angle or caudal rotation. Ponies, mules and many others with very upright feet have a strong palmar angle (15 – 20 degrees). The angle changes constantly with horn growth and routine trimming and shoeing. Farriers that are conscious of the angle and how they can influence it have a tremendous advantage over their colleagues. Range of normal will vary somewhat even among light breeds. Light breeds with healthy, strong feet normally have between 3- 5 degrees in front and slightly higher behind. Many Mustangs will be flat (zero), most domestic horses that are zero have crushed their heels and have folded the heal tubules forward. Significant lamellar damage often precipitates rotation of PIII around its axis apparently due to the action lever of the toe resisting the normal pull of the deep flexor tendon. As the digit rotates around PIII the palmar angle increases. The palmar angle increases as rotation occurs, very chronic cases may have 15 to 20 degrees palmar angle and 30 to 40 degrees capsular rotation. Measuring capsular angle of rotation once noticeable, distorted horn growth has occurred is questionable as it is a reflection of horn and lamellar pathology, not rotation around the articulation. Race horses with a 5 degree negative palmar angle must actually rotate 5 degrees just to be horizontal. Without baseline film at the onset these very significant finding may be overlooked. The palmar angle is by far one of the most valuable perimeters for the podiatrist as it offers direct insight to the force of the deep digital flexor and many options that can significantly influence these forces. Having said that, let’s describe a high scale case of laminitis, right front grade 2 club foot, horn – lamellar zone 18/22 mm, 60 degrees hoof angle, less than 10 degrees capsular rotation, 15 degrees palmar angle, 2 mm. of sole depth sagging below the shoe and grade 2 bone disease, a venogram would finalize this assessment. The opposite foot has a hoof angle of 50 degrees, heel tubule angle less than 20 degrees (underun), less than 5 degrees capsular rotation, less than 5 degrees palmar angle, horn – lamellar zone 17/17 mm. (15/15 mm. norm), digital breakover 50 mm., extensor process less than 15 mm. If this is the first film how do we determine what is new and what is old damage? If this is the first few days of the syndrome we could be in big trouble. The club foot has significant bone damage characteristics of chronic apex loading; some of the rotational forces could be associated with the club which is quite normal. The opaque zones will help determine this if you can see it. Ten degrees is too much displacement though for a mid scale club, possibly though a few recurrent abscesses have thickened the horn – lamellar zone. How do we know where he is in the syndrome? Subsequent comparative film, coupled with clinical signs is helpful but may require 3 – 10 days to pick up any subtle changes. Secondly, digital venogram is extremely helpful when trying to determine how old a displacement lesion may be. Acute lamellar tears have a very characteristic pattern, old scars do also, remodeled circumflex vessels appear totally different from acute prolapsed vessels. I encourage any podiatrist to learn this technique, use normal animals to gain confidence, competence and a basic range of normal. Lucent areas: Sub wall and sub solar; where are they and how extensive do they seem to be? Especially the lucent lines that run the entire length of the sole and most of the wall, draining tracks – where are they and how extensive? What is the color of the exudate and how much draining is present on a daily basis. Gas density lesions can be in many areas of the digit, all these for a very specific reason. A first glance it is easy to assume that all lesions found in a specific location have the same etiology but closer examination reveals stark differences in shape and precise location. Pertinent facts concerning the history also become important as they often help describe the nature and longevity of the lesion. The sub wall lucent zones that can appear several days to weeks following a significant bout of laminitis occurs just within the stratum medium along the ectodermal lamellar layer. This air dense zone is thought to be nitrous oxide seen as the result of lamellar disruption. The characteristic shape has a smooth linear side, small radius at the most proximal end and a slightly larger radius at the distal end that stops adruptly at the inner sole margin. Even with penetrated coffin bones this zone stops at the inner sole margin. Often there is a lucent line that runs from the distal end of the lucency to the apex of PIII. This area decides the path of travel for the descending coffin bone. The lamellar lucent zone is quite different from that found with advanced white line disease. White line disease is the result of bacterial and fungal invasion of the stratus medium, the non-pigmented (white) zone of the wall. Therefore, the name is quite descriptive as it basically involves only the white zone of the hoof capsule. Anatomist years ago gave the terminal laminae a misleading name when they called it the white line. Possibly the color has changed over the past centuries but presently it is never white but yellow to tan in color in all horses. The striated lines are the end of the ectodermal lamellar junction of sole and wall. As the innermost horn wall deteriorates the terminal laminae are bent forward by the sole as the counter face of the wall is absent. The terminal laminae are most visible in the white line case as the sole has migrated at the outer margin of the wall. This is the first clue that pathology has occurred. There is little or no wall and no terminal laminae along the toe which is quite a different picture for laminitis. The terminal laminae become stretched and distorted as the effects of rotation disfigures the delicate network. The air dense zone that occurs with white line disease starts at the ground surface, small but demonstrable it can be seen at ground contact. The sides of the lesion are very irregular in shape and the apex of the lesion is often pointed with several distinct fingerlike projections. The prior lateral views often reveal a lucent zone that appears to extend into the bone but it actually is only superimposed over the bone which can be confirmed with other tangent views. Most all significant cases of white line disease will have capsular rotation, many times measuring 30 to 40 degrees. The inexperienced eye that is looking for rotation and air density beneath the wall will often be mislead by the similarities of the lamellar lesions. The stark difference are therefore of utmost importance. A closer look often reveals dirt, small stones and sand within the horn wall that has entered along the deficit at the ground surface. The weight of the horse closes this flap when loaded creating a one way ball valve effect. Once the very vulnerable ectodermal laminae become severely compressed by this space occupying, foreign body the horse shows signs of pain, other anatomical areas are compromised with extensive displacement that can occur in same planes that also create a painful response. Regardless most of all cases remain quite sound well after radiographic lesions are quite well established, a totally different picture is found with laminitis. Sub solar lucency occurs for several reasons; those found with laminitis are often due to extensive bruising and/or sepsis of the sole corium. These areas are often trapped with the sole layer as new horn is laid down at the inner face. It is often thought that many sub sole lucencies are abscesses and must be opened. The contrary is often more true. Abscesses that are the result of trauma can be seen in several areas of the sole long after the fact. Invading these areas on a horse that is quickly recovering from a bout of lameness can take weeks to months to heal. Therefore great consideration must be given to the exact location, distinct characteristics, longevity and clinical findings of each case. Coronary band separation This is another important zone to classify. With experience you will soon be able to put it in the right perspective. Ongoing, hot, swollen, painful, draining coronary bands, are super high scale, can be slough time. Also the moist more subtle separations that have a slight serosanguineous drainage are potentially lethal also. The dry separation looks scary but seldom causes a problem. Small suppurative ruptures seldom create a serious threat, I do not rate them but take note of where and how frequent they appear and should go into your data bank as an aid to prepare a treatment design. Venograms This procedure is technique sensitive but offers a world of information concerning the degree of damage and how it relates to the overall prognosis. The scope of this paper does not offer time to dwell on the large range of norm or large range of damage but I will list the unique characteristics that spell big trouble. I strongly suggest that you develop the skills for the technique using normal feet for several reasons; time is of essence, the bet film are taken within 30 to 45 seconds following injection to the dye. I like to take 4 to 6 views in this time frame. The contrast rapidly leaks into the interstitial tissue reducing the accuracy of interpretation. It is best to become familiar with several normal contrast patterns before attempting to read pathological changes. The most common error is tourniquet leak which will create a stark loss pattern and false negative data. Listed below are examples of contrast patterns that hold significant data and can be used as prognostic indicators. Note: it is vital that you obtain full digital perfusion before attempting to read the venogram. 1. Stark loss of contrast to the entire digit, this is a dead foot with no where to go. 2. Total loss of contrast along coronary groove, anterior face, circumflex and terminal arch; extremely grave prognosis. 3. Stark loss of contrast along coronary groove and/or medial or lateral cartilage and laminae due to medial listing or sinking. A very difficult case to say the least, long term aggressive therapy, best hope is for a yard ornament, pasture companion, broodmare (E.T), this is a tough, expensive venture. 3. Moderate to good perfusion along coronary crest and lamellar terminal arch. Prolapsed circumflex vessels and heavy loss of contrast along medial quarter due to medial listing. Reasonably good prognosis for future brood stock, still requires six to eight months recovery. Due to the many variables found between breeds, conformation, environmental influences and overall foot management programs, I encourage you to become competent with the procedure and develop a working knowledge of normal feet before attempting to use the venogram to make life and death decisions. Failure to fill the digit due to leakage can produce a tree top pattern, the vessels in the heel zone are very distinct and more sparse than normal and taper out much like tree limbs. This pattern can be very misleading to the novice eye. Using a meaningful grading system also helps me be more focused on many separate aspects of the syndrome that I otherwise may overlook. As the case proceeds I constantly look for areas of improvement and also stay cognoscente of the areas that are deteriorating, often as one foot gains ground the other will lose ground. Full evaluation of the case on the initial visit is very important as the career, life and death decisions must be made which can be devastating news to clients. I feel as veterinarians, we have a tremendous responsibility to offer viable options to our clients concerning any and all life threatening syndromes. To have a list of meaningful options we must first assess the damage taking into consideration all the points mentioned above. Once we have accurately defined the degree of damage we must use our personal expertise and knowledge of the subject to offer options. The big question; how do we do that when we have had little or no good experience treating this devastating disease process? There are numerous veterinarians and farriers that have a good handle on this syndrome, use them, learn from them and call for help if needed. Study the film, history and evidence presented, we must realize that the career or life of this patient is left in our hands, are we qualified to take that responsibility? If not, we must become competent or refer them to those that are. Twenty-seven years have passed since I received the outstanding student award in equine medicine and surgery and I feel as though I am finally qualified to treat acute and chronic laminitis. The road to this goal set many years ago has been long, treacherous and humbling. Every single case, every foot has it’s unique characteristics, damage and response to therapy. A basic question that clients often ask; how bad is the damage? I often answer compared to what? Then I proceed to determine the damage compared to a normal foot, compatible with the breed and other particulars of the case. The expense of fully evaluating a laminitic case can be very significant and must be discussed before proceeding. Yes, we can pull out an array of suggested treatments and just go for it without a clue what to expect. Many cases have the potential of being high risk, will hold there own, appear to be doing just fine for six to eight weeks. Apparently the foot has a tremendous reserve not offered to any other part of the body. It can withstand long periods of circulatory compromise or collapse with little or no apparent ill effects. This alone is the big killer, as most all mid to high scale cases will appear quite content and maybe only slightly lame on a very minimum dose of Bute for several weeks, then suddenly they are extremely painful. Films taken at this stage often reveal serious PIII displacement. I must caution, using only the attitude and visual assessment of the animal to determine degree of damage is potentially lethal. I encourage all podiatry focused farriers and veterinarians to become dedicated to learning all they know in a different fashion every 24 hours. Learning is contagious and raises the enthusiasm levels of all concerned. Compromise the circulation to any other part of the body to the same degree that the feet suffer and it would be obvious that the horse was in trouble. The foot is quite different and looking at its amazing function it doesn’t surprise me. The highly specialized cells that form the durable digit apparently also have the ability to function for an extended period of time under very adverse conditions with significant loss of circulation. Take good film every five to six days, track your progress or regression before the horse tells you that the foot is going south.

The sole depth is also a critically important soft tissue parameter that can be measured easily and accurately on a true lateral radiograph. Studies report that most light-boned horses require 15mm of sole. An inadequate amount of sole can lead to compromised blood supply and subsequent soft tissue damage. Sole Depth To measure sole depth, simply locate the apex of the coffin bone and draw a vertical line from the solar surface of PIII to the ground surface. Note: If the horse is shod, draw the line from PIII to the top of the shoe. The length of this line in millimeters is the sole depth. In this case, the sole depth measures 4mm. Sole Depth & Cup Some horses will have a natural or man-made cup in their foot. This cup will appear radiographically as a radiolucent (black) area because it is an air pocket under the sole. To accurately measure sole depth, you need to measure the distance from the solar surface of PIII to the top of the cupped area. You then measure from the top of the cup to the ground surface or shoe, respectively. In this case, the sole depth measures 9/6.

2003 - 16th Annual Bluegrass Laminitis Symposium Notes How To Use Self Adjusting Palmar Angles To Treat Heel Pain Written and presented January 2003 by R.F. (Ric) Redden, DVM Traditionally we have been taught to speak of rotation as the most meaningful single pathological indicator within the hoof capsule. Owning and operating an exclusive equine podiatry practice for twenty plus years I must say I never have felt this particular radiographic perimeter to have any significant meaning. It often overshadows more important perimeters that offer endless information concerning drastic changes within the foot. Let's look at a diagram of a radiograph with the most important perimeters. The horn - lamellar zone would be the thickness of the horn, plus the laminae measured in two distinct locations. Any discrepancy in these figures would include a negative or positive capsular rotation or possibly over sculpturing of the horn wall. Neither of which will cause the horse to show the clinical pain that is exhibited with acute laminitis. Palmar angle: Draw a line along the palmar (plantar) surface of PIII, I like to use a line along the wings as they are the natural load zone, and measure the angle they make with the ground surface. This angle becomes very meaningful when dealing with most all foot problems. Using this angle we can be very precise as we manipulate the foot in an effort to enhance the healing environment. Sole Depth: Drop a line off the apex to the shoe surface or opaque wire that is in the top of the x-ray positioning block. If cup is present measure it as well and record, e.g. 15/3 = 18 mm. depth, 3 mm. cup = 15 mm. pure sole. C.E. (Coronary band - extensor process): Draw a horizontal line through the coronary crest, another through the top of the extensor process. The distance between these two lines is the C.E., a very significant perimeter to monitor with laminitis. How do we use the palmar angle to influence the mechanics? First let's consider the support sling of the digit. The deep flexor cradles the navicular bone pushing it against the articular surface of PII and PIII, attached by a very secure anchor to the semi lunar crest of the coffin bone which in turn is anchored to the wall with a very vascular - sensitive lamellar network. The pressure exerted on all these structures is influenced by body weight, speed, footing, conformation and the unique way in which the foot lands, torques and loads. The details of how the foot maintains a healthy state of equilibrium is based on the fact that all members or structures of the support mechanism perform as a healthy, fully functional unit. When one member fails the next one is challenged and soon a cascading series of events is well on its way. One should look at the palmar angle as if it were an idle pulley, working in the middle of a belt drive. Adjusting the tension on the pulley increases the load on the belt as well as the end points. The palmar angle does much the same, but it is located inside the belt so to speak and when the palmar angle is lowered pressure is applied to the tendon, bursa, apex, sole corium, laminae and horn wall. The slightest adjustment greatly effects the circulation as well as sensitivity of the digit. Coupled with the effect of the support outside the sling is the digital cushion, frog, sole, buttress and horn wall. All of which function as energy sink while protecting the sensitive structures. Let's take a look at the hot spots or excessive load zones with a typical pathological case. Navicular disease we will simply call heel pain as it is a multi facet syndrome as a rule with several sensitive structures involved. Using a lateral radiograph, (farrier friendly view of soft tissue detail, pure lateral radiographs with wall and ground markers), let's look at the effects of chronic hot spots. Most cases will exhibit excessive pain to hoof testers with placement over the center of the frog. Many also show pain across the heels, and will resist thumb pressure when pressed deep into the heel bulb area. Most will block with a heel block and often an intra-articular when given a few more minutes to soak in. Most do not like to walk or trot down hill. Most hate it with a passion and do not like to turn in a tight circle especially on hard footing. Discounting the fact that we are looking for a diagnosis, let's consider looking for hot spots and a mechanical solution that simply takes the pressure or load away from the heel area significantly improving the healing environment. I do not need a diagnosis to feel good about fixing a lame horse. I need a solution and so does my client. Let's review a typical radiograph; toe angle 50 - 52 degrees, sole depth 15 mm. (no cup), zero palmar angle, horn - lamellar zone 15/15 mm., C.E. (coronary band - extensor process) 15 mm. with proximal wall bending (high dish just under the coronary band). Radiographs reveal slight lipping at the apex, mild to moderate pedalostitis along the wings of the coffin bone, several small lucent areas superimposed over the body of the navicular bone (seen in several grid views). Many very similar cases will have distinct osteophytes within the impar ligament, spurs on the wings of the navicular or possibly no radiographic lesions but with an identical history. How significant are the radiographic lesions? It is debatable depending on the precise location and effect on surrounding sensitive tissues. Regardless, it really doesn't matter as we have a very consistent means of reducing the pressure to this area. Traditional methods of treating heel pain has been eggbars with slight heel elevation and a pad of some sort, all of which have merit but very low on the mechanical scale. The eggbar supports the tendon apparatus not the heel. It actually increase load on the heel which supports the tendon, but this slight benefit reduces load over the bursa and bone. The wedge can act to decrease pressure over the bursa area also, depending on the relationship of toe angle, navicular bone angle, sole depth and palmar angle. Raising the heel can have a negative effect when only a few degrees are put on a foot with negative palmar angle. Eggbars are so popular because they are inexpensive, easy to apply, and often offer immediate relief of pain to some degree, a horseman's dream. Unfortunately they seldom if every improve the quality, mass of foot, and most often slowly crush the heel tubules reducing mass of cushion and wall strength. Sole depth remains constant (normally thin) therefore the mechanics are not sufficient to offer a better healing environment. Most eggbars are a temporary Band-Aid® that offers temporary relief. The palmar surface of the navicular bone can act as an idle pulley also. It is greatly influenced by pastern alignment. The proximal border of the bone is firmly attached to the back of PII. Broken back axis can increase the palmar angle of the navicular bone while the palmar angle of PIII becomes lower. This is not a good deal as many sensitive structures become part of this syndrome. Very simple mechanics designed to significantly raise the palmar angle of PIII shifts load away from the apex, navicular bone and lamellar zone toward the heel and can have a profound effect on the hot spots. Considering the start point of the existing palmar angle, the goal is to raise it several degrees above the normal palmar zone of a healthy foot with similar conformation. The palmar angle on a large majority of normal feet will fall in the range of 3 -5 degrees on front feet and 5 - 8 degrees on hind feet. Unfortunately a large number of performance athletes have various degrees of heel compression which can be seen as a diminishing palmar angle. This can be confusing to many as it is normally seen, but what is actually normal and healthy can be quite another finding. Grade 2 clubs and higher will naturally have larger palmar angles unless they have been trimmed and shod in a fashion that diminishes heel mass. I have found that wedges push the palmar angle into the desired sweet spot but increase the load on the heel tubules and soon they begin to breakdown. Using breakover or pivot well under the foot offers self adjusting palmar angles. The horse pulls the heel up with the easy toe action by shifting load quickly to the toe. The mechanical efficiency of the shoe can be scored by giving the shoe a point for every two degrees it raises the palmar angle. This is static load evaluation (standing equally on two x-ray blocks) reviewed radiographically. Being able to see this magic relationship at speed and all stages of the load phase would be nice. Let's take an example. Start angles negative five degrees (apex tipped up) put on a rock-n-roll shoe that brings the starting palmar angle up to positive 10 degrees. This would be a 7.5 point shoe. With an acute laminitis case, I like to have a 20 degree palmar angle, therefore we need 25 degree raise or a 12.5 shoe for the foot that is negative five degrees. Traditional shoes with a rocker toe or rolled toe have very limited mechanics as the breakover is limited to the toe branch of the shoe and when this is placed behind the apex the level of mechanics goes up and they move as a unit. We found drastic radiographic differences month after month. The palmar angle, sole depth, and digital alignment relationship become part of the formula as well. Regardless, any and all shoes designed to reduce breakover have positive mechanical properties. How much depends on the previous location of the pivot point and the unique characteristics of the start model. If we look at a foot (regardless of the start model characteristics) shod with a heavy square toe versus the same foot shod with a rock-n-roll shoe, moderate belly, placed directly below the center of articulation of the coffin joint. Photographs and radiographs clearly reveal the stark difference in the effect on the palmar angles. The square toed shoe doesn't change the palmar angle unless the horse moves forward, this is the only time he feels the effects of the mechanics. Not bad, certainly helps performance but is slow to improve sole depth, heel mass and realign tubules. Why? It only works when the horse is moving, if movement is the greater part of his day - great, things will happen. If not, the radiographic perimeters do not change. The rock-n-roll shoe immediately changes the palmar angle at the will of the horse, placed as described the horse has a choice of load zones and they are not going to purposely increase tension on hot spots. If he sleeps standing all day and doesn't move a foot the horse is constantly providing a better healing environment which is easily demonstrated by accelerated sole growth, improved tubule alignment, buttress remodeling, horn growth and overall foot mass. The clinical effects of altering the palmar angle can be very rewarding with many of the common syndromes that are merely hot spots or over stressed areas that have become dysfunctional due to disease or injury. The genetics of the beast has a very intricate healing protocol that we understand a little better all the time. Give Mother Nature a chance to do her thing simply by removing the handicaps and things start to happen. I like to think of healing with the hope of a cure. Many horses can heal sufficiently enough to not feel pain but are never cured of the original problem.

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How to Weld Aluminum Inserts Foot Preparation Trim the foot with a 4-point trim, push the heels back and rocker the toe whenever possible. The rail shoe is then rockered and fitted to the foot. Frog Insert Placement The frog insert should be sized slightly wider than the distance between the heel branches of the shoe. It needs to fit snug inside the heels. After tapping the insert between the heel branches, lay the shoe on the foot and press the insert down onto the frog. This will raise the shoe off of the heel of the foot. Proper position of the shoe and insert will result in a 1/8” gap at the heel when the insert sits firmly on the posterior 2/3 of the frog. When happy with the placement, remove the shoe carefully so the insert remains in place. Welding Preheat the shoe and insert that are being welded together. If the shoe smokes the apron, then it is very close to welding temperature. Place the shoe and insert on a firebrick, instead of a metal surface, during the welding process (a metal surface will draw the heat from the shoe). Using a nice feathered flame, begin heating the large, thicker areas of the shoe until the surface becomes dull gray or milky. At this point, begin pushing the heat toward the weld site. Be sure to keep both the shoe and the insert at the same consistent temperature. Keep the rod close to the flame, but not in the flame, while you are heating the shoe and insert to welding heat. Once at the necessary temperature, place the rod between the flame and the shoe. This prevents the shoe from overheating and allows the rod to flow nicely. If the melted rod beads up and runs off the side of the shoe, then the weld area is not hot enough. In this case, simply let the weld area cool for a few minutes and repeat the process. Benefits Proper placement of the insert and shoe provides excellent positive frog pressure. Tack the shoe on using 2 nails,and set the foot on the ground. Inspect the foot to ensure the 1/8” gap is closed and that the horn tubules are fully loaded on the surface of the shoe. This technique is great for horses with low-heeled feet. It is also critical to maintain a tough, dry frog if it is to be an efficient load-bearing surface. To foster this environment, place a piece of industrial grade paper towel between the frog and the frog support insert. Recommended Items Henrob 2000 The Henrob 2000 is an excellent torch for welding aluminum. It runs on 4 pounds of gas and 4 pounds of air, and offers a very localized heat source for precise welding. It also offers a tip that enables the user to cut aluminum up to 1/2 inch thick, while leaving a clean, finished edge. Flux Cored Aluminum Welding Rods are perfect for general aluminum welding. More specifically, they are perfect for welding aluminum frog supports into any of our aluminum horseshoes. These rods are easy to use and contain an extremely active flux formulation that helps prevent oxidation at the weld areas.

Indepth Equine Podiatry Symposium Notes Written and presented January 2009 by R.F. (Ric) Redden, DVM Canker foot carries a wide variety of meanings. The basic characteristics of the disease are white, proliferative finger-like projections along the coronary band, a musty (fungal) odor and/or deep necrotic, non-sensitive involvement of the sensitive frog, digital cushion, sole corium and laminae. There is very little if any useful data in our current text books to help define the various stages of canker or the many different forms it can manifest. Older texts written before veterinary medicine was a reality are also vague, designating many different pathological processes as canker. Canker falls under the broad category of pododermatitis, which is descriptive to some degree but very misleading for the case with very extensive necrotic damage to the deep structures of the foot. The fact is, this disease occurs throughout the world yet remains quite a mystery, as we do not understand the challenges of the various forms that all appear to be related. Over the years I have dealt with many cases categorized as canker, from its initial to advanced stages. Incidence Contrary to popular belief, in my experience this disease is not limited to horses kept in low hygiene conditions. Some of my most difficult cases have come from top level racing and training stables that maintain the highest level of hygiene. It does not appear to be contagious either, as I have only seen one instance in which more than one horse from the same farm or stable developed canker. In that case, several show quality Clydesdales were presented to me with very extensive, advanced lesions, some in one foot and others in all four. They were from a farm in Ohio that had previously been a major hog farm, but any possible connection would be speculative. Draft breeds are apparently more prone to canker, possibly because of the long feathers and dense, coarse hair that is characteristic of the breed. The lack of air to the skin in the lower leg and coronary band along with the cumulative effects of bacteria and fungus that persist in this area could be a direct cause of the increased incidence in these breeds. However, it certainly does not explain why other breeds that have extremely short hair and often get daily baths can have such a serious incident, often appearing to originate within the digital cushion and frog sulcus. I have seen this condition in warm bloods, Thoroughbreds, Standardbreds and only a few mixed breeds. Possibly other breeds have this condition with the same incidence, but I cannot say that from experience. Clinical Differences Between Thrush and Canker During the initial stages of canker, most horsemen almost invariably feel they are treating thrush that simply won't go away. The majority will use caustic agents to dry it up, which works quite well in most thrush cases. However, when canker is the culprit, products that burn or cauterize the sensitive tissues seal the canker inside, frequently causing it to spread throughout the digital cushion. Thrush is caused by an organism initially referred to as xerophilic Nectria, but now called spirochaeta. Both terms have destructive connotations, but they are simply low virulent organisms that have frog lysing properties when conditions allow them to multiply. Thrush starts along the sulci of the frog. The deep crevasse that appears periodically in a variety of foot stereotypes can harbor moisture and causative organisms that find it ideal for growth. The result is thrush. The area is tender to a hoof pick but does not cause a lameness concern. The unpleasant odor is typical of this organism. Canker also has a rank odor, but it is more of a musty odor that we commonly find when fungi are involved. Characteristics Canker appears in many forms and has been thought to involve the skin of the lower leg as well as the foot. I will focus on the disease as it affects the foot. Canker may involve one foot or all four. The very mildest form appears as an inflamed coronary band with a villainous growth of tissue that appears as soft, white projections with a fungal odor. More extensive cases can have a non-sensitive, necrotic appearance that can destroy the sensitive frog, digital cushion and sole corium in various degrees. It can also appear as a yellow, cheesy layer of tissue that involves the sensitive frog and digital cushion. Both problems get very little respect at the onset as the horse is not lame. Thrush can be successfully treated simply by cleaning up the foot with soapy, hot water and packing dry gauze in the deep confines to prevent air from getting to the deeper areas. I prefer to use a 50/50 solution of iodine and glycerin to treat thrush, as it doesn't burn the tissue and quickly kills surface organisms. Canker on the other hand, does not respond to this treatment, and as stated goes rampant when sealed behind caustic burns. When canker appears in the heel area or reaches the surface through an existing quarter crack or angle of the heel, some may mistake it for an abscess and treat it as such. However the horse seldom shows any sign of lameness and a large majority of cases continue in training relative to the size and extent of the lesion. This is non-typical of any and all abscesses that most always cause a painful response. Etiology As a rule, it is helpful to know what organism we are dealing with, but with canker that remains a mystery. We can culture corneybacteria, which is most likely a contaminant. Spirochaetas are also routinely found within the necrotic tissue. Other researchers say it closely resembles neoplasm. The bottom line is that we have no clue how this problem starts or why it is manifested in so many different forms. Treatment Mild invasion In the early stages the hair along the bulbs of the heel and coronary band will stand out instead of lie down over the coronary crest. Looking closely you will see small, white hair-like projections that can easily be removed with an abrasive cloth or tool. There is a distinct odor typical of fungi once this tissue is debrided. The hair-like projections can be removed every day and still reappear the next. The coronary band can also appear quite hyperemic and can easily bleed with abrasive massage. When this stage appears it behooves us to closely examine the frog and adjunct horn tissue for any involvement. Often the organism will be embedded deep within the sensitive frog and digital cushion and can only be detected in a very small area on the surface. Clean hooves daily with hot, soapy water. Physically remove the surface hair-like projections with abrasive action. Cover the diseased area with a thin coating of tetracycline sulfamethazine paste. Tetracycline is apparently effective in eliminating the spirochaeta, and SMZ is a broad spectrum antibiotic for commonly found bacteria. This product was developed by my colleague, Dr. Carrie Long, and I now use it on all my cases. Moderate invasion A small, thumb-sized area of tissue with a yellow, cheese-like appearance that does not appear to be part of the frog or digital cushion is indicative of a more moderate invasion of canker. This area needs to be surgically removed to include a couple of millimeters of surrounding healthy tissue. I have had little luck being conservative when the digital cushion is involved. On occasion, even the smallest surface area will only be the tip of the iceberg. The entire frog and a large majority of the digital cushion and sole corium and even laminae in the heel and quarter area may also be involved. Apply a hospital plate shoe prior to surgical debridement. The plate serves as a bandage and offers a means to apply pressure to the surgical site, which is a prerequisite for healing. Pressure also suppresses granulation tissue. I've found this to be one of the most important aspects of treatment. Using a tourniquet and local anesthetic, surgically remove all diseased tissue plus a thin layer of healthy tissue. Pack the area firmly with gauze soaked in 2% Betadine. Change it daily. Severe invasion When the non-sensitive frog and surrounding horn is undermined, the organism has most likely penetrated deep within the foot. It is not uncommon to expose the DDF simply by debriding with dry gauze. I often wonder how the horse can remain non-painful as such a devastating organism destroys the foot. Trim the foot, avoiding all necrotic tissue until the shoe is applied. Apply a hospital plate that reaches up around the bulbs of the heel. This is important as most advanced cases also involve the bulbs, necessitating firm pressure post surgery. Sedate the horse and block the foot with an abaxial block.Apply a tourniquet. Using a pair of Allison forceps snapped onto the tissue that needs to be removed, start in one area and attempt to dissect the diseased tissue from the underlying healthy corium and cushion, taking approximately 2mm of healthy tissue. Removing it in one piece greatly facilitates our ability to get all of the diseased tissue. Know before you start that this is not a little debridement. You may be removing a large majority of the structures of the entire posterior half of the foot. Be very careful not to involve the navicular bursa, tendon sheath or coffin joint. Pack the area with 2% Betadine soaked gauze and fill the remainder of the area with Advance Cushion Support before applying the hospital plate. Note there will be considerable hemorrhage once the tourniquet is removed. I prefer to over-pack the foot for the first few hours post op, then remove a very small area of gauze or trim the plate side of the ACS. We need the excess packing only until hemorrhage has ceased. Too much pressure for 24 hours traumatizes the sensitive tissue, but too little allows granulation tissue to grow rampant. Experience will help you get it just right. Remove the plate, rubber and gauze on day two. I prefer peroxide as a means to soften the clot adhering the gauze to the sensitive area. Make a paste using LA 200 tetracycline and SMZ tablets. Put a thin layer on a gauze pad and cover the area. Fill the remainder of the foot with ACS. Cut the bottom 1/3 of the ACS off with every change and add a new layer of ACS that will fit the conformation of the surface as it heals. Then make a new filler pad when indicated. This continually suppresses granulation. Keeping direct but firm pressure assures optimum results. The most severe case requires a minimum of 60-90 days to heal. Most cases go on to be sound athletes. Occasionally the growth centers of the horn are drastically distorted, resulting in a variety of horn growth abnormalities. This sounds like a radical approach to a problem that doesn't make the horse lame. Keep in mind the majority of my cases have come to me as a last resort following months of more conservative treatment.

Written for the International Equine Veterinarian March/April 2013 Issue by R.F. (Ric) Redden, DVM Radiographs are an essential part of most physical exams of the lower limb and foot, whether the focus is a pre-purchase, exam or soundness issue. Veterinarians are responsible, licensed and required by state law to take and interpret radiographs, make a diagnosis and formulate a treatment plan, which is a straightforward process that does not require the input of other professions until the exam is focused on the foot. Farriers share a significant responsibility for the overall health of the foot in spite of having limited or no formal education in farrier services or veterinary medicine, and are expected to maintain strong, healthy feet, prevent imbalance and its ill effects and treat and correct many commonly occurring problems that can threaten the career or even life of the horse. Veterinarians, even though licensed to treat the foot, as a rule have very limited or no farrier experience or skill however are expected to have as much working knowledge of the foot as the farrier and vice versa. Caring for the equine foot is an overlapping, duel responsibility that requires a totally different mindset, level of knowledge and skill that encompasses the basic principles of each profession. Veterinarians and farriers who accept the responsibility of treating career and life threatening foot problems need to take this responsibility very seriously and constantly strive to strengthen the weak areas of their respective knowledge branch and experience. Radiographic information is the missing link that can help bring farriers and veterinarians to the same page. By taking the standard recommended radiographic views a step further and educating farriers to read and understand radiographic information, we develop a "platinum" standard of care that can increase the accuracy and degree of information a vet/farrier team can use to improve their ability to care for the foot. Bridging the gap with platinum standard radiographs The farrier with years of extensive experience trimming, shoeing and forging develops an eye for detail that can only be gained through hands on day in and day out. However the most valuable information is most often not available and many have not had the opportunity to work with veterinarians willing and eager to teach basic radiographic interpretation. Therefore they are limited at best when attempting to sort out an internal problem by altering the shape and balance of the capsule. Developing my exclusively equine podiatry practice and clinic three decades ago led me on a pursuit for knowledge and success with a multitude of career and life threatening foot syndromes. Every case demanded more and more information, better interpretive skills, improved planning and better execution of the plan. I had to develop a more meaningful approach to gathering radiographic information that would give me answers to questions raised by routine radiographic views. This search opened my eyes to the mechanical formula that is the direct link from film to rasp, and how important it is to understand the effect internal structures of the foot have on the outside. The next step is teaching this information to other veterinarians and farriers. Putting everyone on the same page allows us to develop common goals and an efficient way to achieve them. Simply put, veterinarians and farriers who study together can greatly enhance their knowledge and perception of the radiographic information they need to make it happen. What follows is confidence and understanding: the hallmarks of success. Designing and utilizing the platinum standard Standard, recognized radiographic views are informative but limited relative to the information required to understand the mechanical requirements of a foot. Beam orientation and other factors affect specific areas of interest. Therefore we must modify our protocol in order to get the most accurate film with the best information to base our interpretation and decision making from. I refer to this consistent, dedicated protocol as the 'platinum' standard of hoof care. The farrier friendly lateral view: Beam orientation is crucial for accurate measurement of soft tissue parameters that are of the greatest concern. The primary beam should strike the hoof in a horizontal plane between the palmar rim and ground surface and perpendicular to the sagittal plane. Lining up the heel bulbs works well when they are relatively symmetrical. Proper beam orientation will reveal one branch of the shoe, as the primary beam superimposes one over the other. Zero film/subject distance minimizes magnification. Opaque wall marker (paste preferred) from the hairline of the coronary crest to the toe is required for traditional as well as digital film to assure accurate horn-lamellar (HL) zone and coronary/extensor process (CE) measurements. Both feet should be placed on blocks in their natural stance regardless of conformation. Figure 1: Low beam projection ensures only one branch of the shoe will be visible on the lateral radiograph. This beam orientation makes it possible to accurately and comparatively measure certain key soft tissue parameters such as sole depth and HL zone (provided radiopaque paste is present from the hairline to the toe). DP view Low beam orientation just like the lateral. Two block technique.Head held straight and forward; as the head moves so do the digits and articular surface. No wall marker. Figure 2: A low beam projection DP view allows accurate assessment of medial/lateral balance and sole depth under each wing of PIII. There are several parameters that are important for the farrier to know, as each is altered with every trim and shoeing procedure. When pathology and imbalance requires specific mechanical benefits, it is vital that the farrier know what they have to work with and what, if any, limitations need to be addressed before they start. Those parameters are: Sole depth (SD): Measure the vertical distance between the apex of the coffin bone and ground or shoe surface, to include the cup of foot if present. Palmar angle (PA): Measure the angle made between the palmar rim and the ground. When the apex is eroded or altered by load and/or pathology, measure along the straightest part of the wings. Digital breakover (DB): Measure by dropping a vertical line from the apex to the ground surface, then measure the distance from this line to where the toe or shoe leaves the ground. Bone angle (BA): Farriers as well as veterinarians and horsemen need to be well aware of a foot's bone angle. Many think all feet are alike inside and should therefore look alike and match outside, but this is a misconception at best. Bone angle can vary from 35° up to 65° and often varies 5-10° between feet on the same horse. The farrier need to know this when asked to match feet that are grossly different. Farriers worldwide are eager to do a better job and know more about the foot they are working with, and most realize that specific radiographic information would help them make better decisions concerning trim, shoe fabrication and application. Other parameters of paramount importance for a veterinarian's interpretation of the overall health, balance and ill effects of various pathological syndromes include: Horn/lamellar (HL) zone: Measured from the face of the coffin bone (just below the extensor process) to the face of the wall, which is marked with radiopaque paste from heel to toe. Paste clearly delineates the surface of the wall along with all growth rings. A lucent area will always exist between the paste and the visual hoof wall, even with digital film. Therefore accurate measurements cannot be taken without paste. The HL zone is measured in two places, at the apex and just below the extensor process, and can only be accurately evaluated with zero film/subject distance and a wall conforming opaque wall marker. Dermal/epidermal (DE) line: This is the opaque linear zone lies between the face of the wall and the face of the coffin bone. It is apparently formed by the increased density of epidermal lamellar leaves along the face of the wall. This zone can be an efficient tool for monitoring lamellar health, e.g. acute laminitis; bone remodeling, e.g. club feet; and load induced syndromes. Coronary band/extensor process (CE): CE is measured by drawing a horizontal line across the most proximal paste marker and another across the peak of the extensor process. Then measure the vertical distance between the two lines. This parameter can only accurately be used as a comparative zone as it varies from only a few millimeters up to 35mm in sound horses, with the large majority being 10-15mm. It is not indicative of sinking unless this zone increases during the active stage of digital displacement due to laminitis. Tendon surface angle (TSA): This angle is measured along the distal half to third of the tendon surface of the navicular bone and varies considerably between feet on the same horse. It can be used as part of the mechanical design requirements for various foot problems. Figure 3: Routinely measuring these parameters greatly enhances the eye for subtle changes that occur due to growth discrepancies, effects of trimming and shoeing and pathology. The information we gain from these parameters helps us better understand the mechanical formula and how we can use it to maximize foot health. Foot focused veterinarians and farriers who routinely measure these parameters on all lateral and DP views, especially before and after shoeing, soon become very proficient in correlating external landmarks with internal parameters and vice versa. This is the only way I know to learn how to read the foot, and it requires time and repetition. Once the parameters are better understood and ingrained in the minds of the team, the mechanical formula becomes very obvious and tissue response to various mechanical applications are easily fitted, measured and monitored along with the positive or ill effects reflected in the capsule (wall, sole, bars, heel tubules), digital cushion and frog mass. The bottom line is that farriers dealing with problem feet are working with one arm tied behind their back them if they are asked to make career or life threatening decisions with a rasp without any clue as to what they have to work with and what is required to make it happen. Veterinarians and farriers who work together and routinely use the valuable information obtained from the platinum standard soon learn the potency of mechanics and the limitless options that can enhance the healing environment, ultimately solving many problems that once seemed insurmountable.

Written and presented July 2006 by R.F. (Ric) Redden, DVM Introduction The present day full rocker motion shoe has a convex ground surface and is designed to offer a self-adjusting palmar angle (PA). For optimum results the most prominent point of the convex surface is placed directly beneath the center of articulation of the coffin joint. The design and degree of rocker dictates the range of PA adjustment. The ability to adjust the PA while in the static state sets the mechanical action of this shoe well above those that do not influence the static PA. Square toes, rocker toes, rolled toes and flat shoes set back under the toe to decrease breakover effort can offer advantageous mechanical action when the horse is moving, but fail to allow self-adjustment when resting. The rocker action has a profound effect on solar fimbrae reconstruction and subsequent sole growth, apparently via the altered Deep Digital Flexor (DDF) tension. Flat shoe enthusiasts consider the shoe radical or extreme as it differs greatly from the more recent traditional shoe. However, blacksmiths in the 14th century were forging a very similar full rocker shoe throughout most of Europe for many problems similar to what we encounter today. Unfortunately, the shoe was not described at the time of popularity, simply because there were no authors, editors or printers publishing books during that era. Today, it has once again become an extremely valuable tool for treating foot ailments that are influenced by the DDF. Indications Sport and speed horses are frequently diagnosed with caudal heel pain and long toe, underrun heels. Clinical and radiographic examination reveals that a broken back digital axis is a common finding in horses with crushed heel syndrome. It is common knowledge that horses suffering from the long toe, lower heel syndrome require less breakover to combat the effects of long toe. Backing the toes up has been considered a reliable means for aiding breakover. Unfortunately, pulling the toes back has very limited mechanical advantage. Removing the face of the wall back to the stratum medium gives the illusion that the toe angle has improved, though the PA and heel angle have remained unchanged. Wedge shoes and pads are frequently used to correct the low toe angle hoof as they are an effective tool for correcting the PA to some degree. The positive effects of the wedge can often be seen immediately. Unfortunately, the downside of raising the PA with a wedge too gradually from toe to heel is that it invariably crushes the digital cushion. Use of wedge rim pads or wedge shoes allows the frog and cushion to fall through the shoe, further compromising the heel tubules. Despite the long term ill effects of this method, the concept remains popular simply because the technique of backing the toe up and using a wedge system greatly enhances the appearance of the foot. The thought that if it looks good it must be healthy is a common misconception. The full rocker motion shoe has numerous mechanical advantages that allow self-correcting digital alignment. The rocker action greatly enhances the static stance phase that does not occur with flat shoes, square toes, rolled toes and shoes set back under the toe. The advantage this shoe has over all other flat shoes is the ability to quickly and easily alter tension in the DDF. Load forces are constantly being transferred from areas of inflammation to less painful, healthier areas of the foot. Therefore, from the clinical as well as radiographic follow up, the shoe has the capability to enhance the healing environment for a variety of foot problems that are influenced by the DDF. The majority of foot pain is illustrated by the force of tension or compression. Most problems occur in the toe or heel. Apparently, as the PA rocks forward, this shoe relieves tension forces on the laminae and therefore the sole compression. During the same action the heel tubules are compressed and tensions over the navicular bursae, navicular bone and associated ligament attachments are reduced. Thin soles, white line disease, full thickness toe cracks and laminitis are syndromes that affect the toe area. Reducing tension forces on the wall, laminae and compressive forces on the sole corium aids healing by enhancing perfusion to vital growth centers of the sole and horn wall. Venogram studies suggest that direct correlation exists between increased perfusion and growth center stimulation. The crushed and underrun heels and inflammation of the heel apparatus in general is a major cause for chronic heel pain found in most all breeds. The shoe offers a means to shorten the stance phase while moving and resting, apparently reducing compressive as well as tension forces within the heel area, which subsequently reduces pain. Specific Uses of the Shoe Thin hoof walls and thin soles are frequently encountered on performance or speed horses. Farriers are often accused of removing too much foot. Perhaps some do, but the competent farrier knows when there is no foot to be taken off. In these cases, close observation will reveal 3-4 sets of nail holes in a foot, confirming that no foot has been removed and little growth has been present for the past several resets. Farriers routinely brush the dirt and broken horn tubules off the ground surface and either try to find a place to secure a rail or use composites to attach the shoe. Foot mass diminishes for many other reasons than a visit from the farrier. Lack of demand on the foot, excessive moisture, nutrition, speed and other man-induced demands on the foot have cumulative effects on the strength of feet. Inherited and congenital weakness compounds the problem, as the reserve offered by a strong, upstanding hoof capsule is simply not there. Using the full motion rocker shoe as a tool to aid quick mass recovery is one of its most promising assets. Venogram studies by Redden1 suggest that healthy, vascular supply to the sole corium and heel apertures requires 10-12mm of space below the palmar plantar surface of PIII. A PA of 3-5 degrees is required to sustain the solar papillae that are responsible for sole and other sensitive structures of the heel apertures. Sole proper and horn wall structure play a major role in protecting those vital growth centers. The minimum depth of sole required to adequately protect and support the vascular supply is breed and use dependant. A minimum of 5-8mm of sole (non-sensitive) is considered adequate in most light breeds. Therefore a healthy foot on a light breed horse should have a minimum sole depth of 15-18mm measured radiographically from the ventral side of the apex to the ground or shoe surface. This measurement does not include a 3-5mm natural cup of the sole that can also be measured radiographically. Most all horses lose hoof mass once in training, as sole depth diminishes. Farriers often feel obligated to cup the sole to reduce sole pressure on the shoe. However, cupping the sole that is losing mass soon becomes counterproductive. Cupping the foot that doesn’t have a cup is detrimental to the foot as the protective, supportive function of the sole is greatly reduced, setting off a cascading series of events that further weaken the capsule. As the sole thins the wall follows pursuit. Stimulating accelerated sole growth likewise stimulates rigid horn wall growth. Further studies are needed to better understand the mode of action. Anatomy of the Shoe Any shoe can be forged with a convex ground surface. The depth of the shoe branch and the design, e.g. flat, wedge, rail and the degree of convexity, determine the mechanical potential of the shoe. To help simplify mechanical action, the author has developed a scoring system. For every 2º the PA is altered in the static state the shoe gets a score of one. For example, the shoe required to raise a pre-shoeing PA of negative 4º to a post-shoeing PA of positive 6º would be a 5 point shoe. The shoe is designed to set solidly on the anterior quarter of the foot referred to as pillars by Duckett and the posterior quarter, which is located on either side of the foot at the widest part of the frog. The degree of convexity or rocker will depend on the predetermined goals, the problem you wish to solve, the mass of hoof present (sole depth and horn quality), and the PA, The breed, gait and intended use must also be considered. Informative soft tissue detail lateral and AP radiographs are required to accurately design and fit the shoe to meet the mechanical goals in mind. Post shoeing radiographs are required to confirm whether the mechanical goals were met and to set the new base line, which is needed to accurately record progress. Shoe Attachment Several methods of attachment are available depending on the severity of the problem, and rehab vs. continued training. When adequate foot mass is present the nail pattern is placed in the center and either side of the most convex part of the shoe. This attachment site assures that the shoe moves at the same speed as the horse and is not trapped on the ground as the foot breaks forward. Nailing in front of the widest part of the foot has long been advocated for flat shoeing. This concept is thought to prevent entrapment and contraction of the heels. Further studies are needed to confirm the validity of this concept. Flat shoes nailed anterior to the widest part of the foot are often stationary as the heel comes up in an attempt to start breakover. This “loose shoe” appearance will invariably create large oval nail holes in a matter of days and weaken the wall adjacent to the nails. The full rocker shoe attached at the center of the convex surface shows little or no nail hole wear from reset to reset, indicating it is not resisting the movement of the foot. Adhesives - The shallow foot (less than 15mm of sole with a zero or negative PA) cannot be trimmed to meet the convex shape of the shoe. Therefore to apply the desired mechanics the shoe can be set into a bed of composite and held off the ground until it has cured. Nail and Adhesive – A combination of adhesive and a couple of nails also works well for the shallow foot. Caution is due. Driving nails through the cured composite can create problems by deflecting the nails. Cleaning up the nail holes before the composite cures is recommended. Trimming the Foot The depth of sole and the PA are basic deterring factors for all trims regardless of the goals for the shoe. For example, there is very little to trim on a thin soled horse (less than 15mm and with a zero or negative PA). Determining how to fit a rocker rail to this foot requires rasping the toe (ground surface) at a very low angle (10-15 degrees) in a plane perpendicular to the long apex of the foot. The goal is to produce a flat, smooth plane across the sole well in front of the location of the apex of PIII. Removing sole directly over the apex of this foot is not conducive to better soundness. The heels are then backed up from just behind the widest part of the foot to very close to the widest part of the frog. Removing the section of horn tubules that are bent forward and folded towards the midline of the foot offers a more solid end tubule loading and significantly increases shoe/horn contact. Caution is advised when fitting a full rocker shoe to this type of foot. The frog should not be touched. Fortunately, most thin soled, underrun heeled feet will have a wide, thick frog that protrudes well below the bearing surface of the heel tubules. To effectively push the heels back with a prominent frog, the rasp must be worked along the sides of the frog. Removing frog to get to the heels is a common error and often the cause of post-shoeing lameness. Fitting the Shoe Deciding on whether to rocker a flat shoe, rail, wedge or a full rocker shoe depends on the complaint (ailment), whether the horse is rested or trained, and what degree of mechanical action is needed to adjust load and/or internal tension from areas of influence to sounder parts of the foot. Once the shoe is selected it is fitted to the shape of the foot allowing approximately 1/8 inch of extra width on either quarter. Using a rocker jig or the step of the anvil the ground surface is forged, creating a smooth, convex ground surface. When forging, start the rocker at the heel and work forward to assure the most optimum point of convexity is at or slightly behind the widest point of the foot. Once the desired amount of rocker has been applied to the shoe lay the heels of the shoe (ground surface) on the face of the anvil and soften the last 1-1 1/2 inch of the branch. This is a vital step. Allowing the convex surface to continue into the bulb area will invariably cause post shoeing pain. This is a common error that many farriers fail to detect. When the shoe is fitted properly there will be an air space between the toe of the foot and the toe of the shoe, and the shoe will sit solidly on the four points of contact. The shoe will not sit on the quarters. When a large air space is present (4-5mm) the shoe will require a bed of composite to offer adequate foot/shoe contact. Nailing with a small 2-3mm air space under the quarter does not pose a problem. How to Determine Radius of Convex Surface The principal design of the shoe offers a variety of mechanical influences on the PA. One of the goals of the shoe is to re-establish healthy digital alignment. The majority of horses do not have matching feet, PA, bone angle or toe angle, therefore the mechanical demand will be different from foot to foot. Normally when used as a rehabilitation shoe on a case that is not in training, the higher score shoe would be used with the goal of promoting accelerated sole and horn growth while the horse is out of training. For example, the performance or speed horse that has a sole depth of less than 7mm or a zero to negative 5 degree PA and very poor quality, thin walls can benefit greatly with a couple of 4-6 week periods using a 5-7 score shoe. This would be considered a moderate rocker. Many times hunters, jumpers, cutting horses, reining horses and other slow sport horses can go back into training with the same degree of rocker once the foot mass has been restored. Some compete well with new foot mass and the same mechanics, where others need slightly less mechanics. Tendon surface angle (TSA), heel and toe angle may differ greatly between two feet on the same horse. Therefore, slightly different mechanical action is indicated for each respective foot to correct digital alignment. For example, the club foot with thin sole and a zero PA will need only slight to moderate rocker to achieve desirable PA. The opposite foot with a negative PA will require a higher score shoe to offer the same self-adjusting healing alignment. The score of the shoe is influenced by the shoe design, how much rocker is in the shoe and where the peak of the rocker is located. Moving the rocker from the widest point towards the heel increases mechanical score. Speed horses – When race horses are diagnosed with sore feet, pedalostitis, heel pain and often quarter cracks, the trainers are looking for a quick fix. Re-establishing sole depth and rejuvenating crushed digital cushions with horses in full training is a much slower process than in the horse that is laid up for a few weeks. A much lower profile shoe (less mechanics) is used on speed horses that remain in full training. Using a very low mechanical shoe on a horse in training will yield small improvements in sole depth, heel mass and horn growth; therefore the speed of progress is limited. The low profile rocker is placed on the foot in the same fashion. Normally it is glued on with composites for the first few shoeings, and the peak of the convex surface is positioned in a fashion that offers center to toe loading when static. Most low score shoes can change the PA 4-6 degrees without taking any foot off. The author recommends all speed horses be shod a minimum of 4-6 weeks before going at race speed. This offers healing time (though limited by training speed) and gait adjustment. Once reset, the foot mass, digital alignment and muscle soreness associated with extremely low PA has normally been improved and the horse has adjusted to the shoe. Informative venograms are very useful as a tracking tool as they clearly reveal the speed and degree of solar fimbrae reconstruction, which appears to play a major role in healthy sole growth. Results The full rocker motion concept shoe has been used frequently over the past several years by the author in his exclusive podiatry practice. Long Toe, Underrun Heel All breeds world wide with a long toe, underrun heel condition appear to be prone to losing heel mass once put into strenuous training. The author has treated numerous cases in Thoroughbreds and Standardbreds (race and brood stock), American Saddlebreds (show and brood stock), Morgans, Tennessee Walking Horses, Quarter Horses, several warm blood breeds and cold blood crosses. The typical long toe, underrun heel has a broken back digital alignment. The severity of the imbalance is relative to the palmar angle and level of pain. The mechanics are adjusted to meet the digital alignment in the static plane. Foot trim and shoe attachment is critical and should only be performed by farriers with good working knowledge of the internal structures of the foot. The availability of pure lateral, soft detail AP and lateral radiographs can offer valuable information for the farrier who can accurately interpret the radiographic soft tissue parameters. Take caution, as farriers who work without the benefit of current film, or find it difficult to interpret the information provided by the film may find it very difficult to find success with this concept. The heel and toe are often compromised by excessive and direct load when overzealous trimming has preceded an improper rocker shape and/or application. Tremendous sole growth occurs within weeks when the horse is out of training. Training horses require less mechanics (lower score shoe) and therefore respond much slower. The speed of the accelerated sole growth apparently is due to the ability of the shoe to enhance perfusion to the sole corium. The effects of the shoe on the solar papillae can be monitored via digital venograms. As the papillae reappear, normal, anatomic space and sole production is evident. Crushed Digital Cushion The underrun heel is the result of cushion compression without recall. As the support cushion becomes compressed and compacted the PA decreases, in turn producing a broken back digital alignment relative to the degree of PA decrease from the norm of the individual. The unique conformation of specific breeds influences the correlation of PA to digital alignment. The majority of individuals within the domestic breeds require a minimum PA of 3-5 degrees in order to maintain digital alignment. Exceptions normally have a coffin bone angle that is lower than normal. Speed horses are frequently examined with less than 7 mm of sole and a zero to negative 7 degree PA. This degree of imbalance is not compatible with longevity and is often associated with compensating leg injuries and catastrophic breakdowns. Cushion regeneration and heel tubule realignment is aided by custom fitting a positive pressure frog plate to the custom fit rocker shoe, whether it is flat, rail or full rocker. The frog must be tough and remain dry and tough during use if the shoe in order to be used as a support member. The frog with high water content is soft and vulnerable to compression and compaction, greatly limiting its ability to support direct load. White Line Disease Using a 6-10 score rocker rail fitted with zero PA between the foot side of the shoe and wings of PIII from the widest point of the foot to the heel and a minimum of 20mm between those two surfaces offers an effective adjunct to therapy. The mechanics of the shoe provides adequate reduced DDF tension, directly reducing internal stress on the horn wall. Often this mechanical advantage helps promote new horn growth without fungal invasion. Accelerated sole growth also appears to aid recovery as most white line disease cases have very thin soles due to impaired papillae function. Radiographs taken when the shoes are reset clearly distinguishes the case that fails to be responsive and requires aggressive wall removal to aid debridement from the case that is responsive. The shoe can be altered in a variety of ways for the case that requires major wall removal. Used with a positive pressure frog plate, the rocker rail provides a reliable means of protecting the vulnerable sole and coffin bone while enhancing sole and horn growth. Most all therapeutic shoes can be applied without nails, which can enhance wall regeneration. Chronic Laminitis The full rocker shoe has been used very successfully to treat numerous stages of laminitis. The author does not recommend this shoe for the very early stages of laminitis as other more non-traumatic, higher mechanical devices are available. The mid to high scale case may require several weeks to start growing sole while wearing an Ultimate® before going to the lesser mechanical shoe. Chronic laminitis months to years old have benefited from the shoe when fitted with a zero PA between the wings of PIII and the shoe is rockered to meet the mechanical requirement that is relative to existing PA. The goal is to shift load to the heel and away from the apex. Therefore the PA, when shod, should be elevated or greater than the starting PA. Full Thickness Toe Cracks Full thickness toe cracks, thin soles, and frequent abscesses that break at the coronary band are frequently encountered in brood stock. The shoe has been used successfully on numerous cases. The majority of feet treated have 10-15 mm of sole growth and _ inch to _ inch of new horn growth proximal to the crack within 30-45 days of application. The mechanical advantage of a 6-10 score shoe is readily evident with these cases. The author advises farriers to develop the technique and hone their skills with this shoe on chronic toe crack cases. The horn response is dramatic over a short period of time and the risk of unknowingly violating the basic principle of the concept is much less than with thin wall performance horses. Navicular Syndrome Pain arising from the navicular bursae, or navicular bone, and associated ligamentous attachments is apparently due to load and tension sustained by these sensitive structures. Load and tension are apparently influenced by the direct action of the DDF. Reducing DDF tension with a self-adjusting PA has been a useful means of reducing pain in the navicular area. Conclusion The Rock ‘n Roll shoe has been a reliable adjunct to therapy for several foot problems. The shoe concept has been very beneficial for cases that have problems associated with less than optimum foot mass as it consistently accumulates sole and horn growth, enhancing the protective function of the horn capsule. Sole mass is often restored to adequate levels in 2-3 shoeing periods. Crushed digital cushions responds well when the shoe is used with a positive pressure frog support. Young horses respond more favorably than older, more chronic cases. Best results are obtained when the horse is out of training, as higher score mechanics can be used with the resting horse. Training animals can benefit from the shoe provided the mechanics elected are compatible with gait, speed, terrain and training needs. The shoe has offered beneficial results with several syndromes that are directly influenced by the DDF. Used as a means to offer self-adjusting internal load shift, the shoe can be used as a diagnostic tool and enhance the healing environment. References: 1. Redden RF. The use of venograms as a diagnostic tool, in Proceedings. 7th Bluegrass Laminitis Symposium, 1993; 1-6.

2009 In-Depth Equine Podiatry Symposium Notes Written and presented January 2009 by R.F. (Ric) Redden, DVM Toe Cracks Full thickness toe cracks are frequently found in brood stock and a few sport horses. The cracks are the result of mechanical failure. Normally the anterior/posterior balance is off the scale, and the horse has a long toe, underrun heel and dropped soles. A club foot can develop an abscess in worn areas of the toe that have been invaded by bacteria, which invariably breaks at the coronary band, resulting in a permanent scar. The wall fractures due to internal bending stress and the lack of anterior hoof capsule integrity. As the deep digital flexor (DDF) transfers load to the bone, the bone pulls on the laminae that were once secured to a very strong but now weakened wall, and the system fails. The laminae pull causes closing of the crack when the foot is loaded. The sole sags as the bone travels away from the normal arch of the wall, to seek ground support as the wall can no longer maintain the natural internal balance. Many people are surprised that center toe cracks do not open when loaded, as the cow's foot would. It closes and closes very tightly, folding the sensitive laminae in on itself, perpetrating a permanent scar that becomes thicker and more invasive every time an abscess breaks at the coronary band. The sensitive tissue at the top of the crack becomes a painful area. A thin sole and traumatized apex also contribute to the painful condition. Treatment The best option is an example of physics 101: Stop the movement of the two wall sections on each side of the crack and it will heal. There are two basic ways to stabilize the wall with rigid implantation. Pull the crack together and lace or band, or hold it apart and lace and band. I prefer the latter as this is the more natural anatomical position of each side of the crack, and it prevents the inevitable scar that forms when the crack is pulled together. The DDF influence is the major force influencing movement in the wall, laminae and bone. Therefore the major goal regardless of bands, stitches and so forth is to significantly reduce DDF tension, as it continues to be a key player even when the wall is made less flexible with the band. This can be accomplished by creating a 20 degree palmar angle (PA). Using only wedges to produce the 20 degree PA will reduce DDF tension, but also crush the heel very quickly. Wedges and high breakover mechanics will accomplish the same with less heel crush. Add contact sole support (no positive pressure) and sole sag is significantly diminished. Add positive frog and buttress support to help open the contracted heels and you have a highly functional shoe. Once shod in this fashion, the breakover will be directly beneath the center of articulation. The toe is only backed up at the ground surface. The dish will grow off as new horn grows in line with the face of PIII and the new horn wall will remain intact as long as the DDF tension is adequately reduced. As a rule, I no longer band toe cracks unless the described rocker action shoe that provides a 15-18 degree PA fails to promote strong horn growth without evidence of the crack. Very extensive toe cracks that occur in thin wall, poor quality feet may require a metal band to hold the crack apart. The goal for the shoeing concept is to prevent the crack from being pulled inward, closing the gap. If a band is required, I use a 10 gauge strip cut in the shape of the curvature of the wall. Drill three to four 3/16 inch holes in the plate on either side of the crack. Pick the foot up (unload the DDF) and hot seat the band onto the foot. Burn it in good, then place the screws in while the foot is totally unloaded. Four 1/2 inch number 8 pan head screws on either side of the crack work well. Dr. Redden's Toe Crack Treatment Loading the foot or closing the crack can also aid healing, but invariably creates a thicker scar as the laminae is folded tightly on itself. Quarter clips look great on paper but do nothing to stabilize the crack, as it does not open when loaded. They do, however, help hold the shoe on. The high score rocker rail shoe accelerates sole growth and subsequently toe growth. This shoe is often all that is needed to prevent new horn from being torn along the old scar. Chronic cracks that have caused several abscesses at the heels and coronary band will show signs of each blow out. Normally I will band these as well, to assure optimum mechanics. Radiographs used as an initial planning tool and for subsequent resets are an invaluable resource for the vet/farrier team. Prognosis is good for all toe cracks regardless of chronicity or severity.

Digital breakove r (DB) is yet another soft-tissue parameter that Dr. Redden measures as part of his radiographic protocol. It is easily measured on a true lateral radiograph taken with soft tissue detail. This particular measurement is important because digital breakover directly effects the tension on the deep digital flexor tendon, and subsequently the laminae, sole corium, navicular bone, navicular bursa and surrounding ligaments. Follow these steps to accurately measure digital breakover: Step 1 Locate the apex (tip) of PIII and draw a vertical line to the ground surface. Step 2 Locate where the horse's toe or the shoe no longer touches the ground. Step 3 Measure the horizontal distance between these two points in millimeters. In this case, the digital breakover measures 16mm. If the breakover is behind the apex of PIII, then it is referred to as a negative digital breakover.

International Equine Podiatry Center Written June 2010 by Whitney Rohrer for R.F. (Ric) Redden, DVM A twenty year old mare grazes on lush bluegrass in the horse country of Versailles, Kentucky. Despite her age, she's still spry as a fox and races around her paddock like a three year old when the mood strikes her, even kicking up her heels for good measure. She'll only allow herself to be caught if she feels like it and nickers to go out if she stays inside too long. She's not a royally bred thoroughbred, high value broodmare or a flashy retired show horse. In fact, there's not much about her that's remarkable except for one small detail. She only has three feet. (See the WKYT video of Josie in action.) The horse known as Josie has been a longtime fixture at Dr. Ric Redden's International Equine Podiatry Center, where she has lived with a prosthetic for over 18 years. She came to Dr. Redden as a two year old filly after tangling her left rear foot in the guide wire of a telephone pole while trying to evade some aggressive dogs. The accident all but severed her foot at the pastern. Josie's owner, facing recommendations of euthanasia, took the advice of Dr. Dwight Hooten and decided to donate her to Dr. Redden's charitable organization in hopes that there might be an alternative. The alternative was an amputation procedure to remove the remaining attachment of her damaged foot at the pastern. It wasn't going to be easy, though. While her injury location made her an ideal candidate, there was another problem they would have to overcome. "Josie was barely broken to lead when she came to me," Dr. Redden recalled, "which posed a few problems. You need a horse that is cooperative and easy to work with to get the best results, as they have to be willing to tolerate the sling for changes and trust the people who are caring for them. Fortunately it didn't take her long to learn that we were trying to help her, and when she gave us a chance she learned that life wasn't so bad. She's been great to work with ever since." Redden had performed 6 prior amputations, but with Josie he decided a new technique he had developed had the potential to offer her a healthier, tougher stump and better quality life. "I had run into problems before where even though the stump healed with the center flap, it simply wasn't tough enough to withstand the rigors of loading," Redden explains. "I used a small piece of germinal frog tissue as an autogenous graft that I hoped would provide her with a natural, tough stump pad, and she's still here 18 years later to tell me it worked." It worked so well in fact, that Redden now uses the procedure on all of his amputee cases, with a great deal of success. The healing period for the surgery and frog graft procedure took five months, during which Josie was fitted with a temporary prosthesis that was changed every 2-3 weeks until the stump had healed, the swelling had gone down and the transplanted frog was strong enough to support her weight. At that time she was fitted with an elaborate permanent prosthesis with a flex foot and leather top. It was constructed lightly in order to be more comfortable for her, which turned out to be a mistake. "I was hoping she would be comfortable enough to walk around, maybe trot a little," he laughs. "When I put her in the paddock and unsnapped the shank, she took off at a full gallop. She was so happy to be running again. It was one of the most rewarding moments of my life." Josie in fact ran hard enough to pulverize her prosthesis, so it was back to the drawing board. Since then Josie has worn several different designs, including more expensive models that were vacuum modeled and custom fit. Today, she wears a fairly simple clamshell prosthetic that Redden made in his own shop out of cast material, aluminum struts, a foot plate and high tech, shock absorbing silicon. It's easy to change and fairly low maintenance. Josie's amputation has given her 18 years of life she otherwise would not have had, and she makes the most of it. In fact, she seems to enjoy herself more than the average horse. About once a week she is brought in to have the prosthetic removed, stump cleaned and bandage changed. The biggest challenge of this process is not changing the prosthetic, but bringing her in. "She'll drag you into the barn as if to say, 'Let's hurry up and get this over with, I've got things to do.' If you aren't careful she'll run right over you." And don't make the mistake of leaving the gate open behind you when you go in to get her. "If she spots it open you're in trouble. She'll rip right past you and beat you there." It's not all fun and games, though. During Redden's teaching symposiums and Equine Podiatry 101 classes Josie provides a teaching opportunity for veterinarians and farriers around the world, who learn how to design and create a prosthesis that best meets a horse's needs and how to care for amputees. They can also see the benefits of the frog graft, which has served Josie well over the years. Her stump is tough and durable, and actually needs to be trimmed every 2-3 weeks or her prosthesis won't fit. "It's an eye opener for a lot of people who come here," Redden says, "because the mindset out there makes them expect to see an old cripple out in that paddock. When they see Josie and see how happy and low maintenance she is, their whole outlook changes. It's very rewarding." While amputation is not widely practiced - there are only a handful of veterinarians with experience - it offers an alternative to euthanasia and can certainly result in a happy ending. The financial and mental commitment involved is significant, and requires dedicated owners and caretakers. Multiple surgeries can be involved, complications can be expected, and fitting the horse with a final prosthesis is often a trial and error process. And amputation certainly isn't always an option. "Many of my cases have been poor candidates, as the opposite foot already suffered from contra limb laminitis when they were admitted," Redden recalls. Contra limb laminitis is a big concern with any catastrophic injury. Therefore he routinely monitors the health of the blood supply on the good foot and uses high level mechanics to protect it. According to him, the best candidates are athletic horses, such as race or performance horses, that have suffered a catastrophic injury to a hind leg. "Front legs are a bigger challenge," he explains, "especially on large horses." In addition to the logistical challenges, there are financial ones. "Some of my cases had very limited financial ceilings that did not offer the care the horse needed," Redden says. Despite these challenges, Redden has had several cases besides Josie go on to live long, happy lives. One, a Missouri Fox Trotter stallion, has worn a hind leg prosthesis for nearly 16 years after having his leg amputated just below the hock. Blackie, a walking horse, was amputated at mid-cannon on his left front leg and is still content with his prosthetic today. He even survived chronic laminitis on his other foot, which was dealt with at the time of surgery by using high level mechanics. It's not for the faint of heart, but the rewards can be terrific. Just ask Josie.

R.F. (Ric) Redden, DVM. Venogram technique, indication and interpretation, in Proceedings. Bain Fallon Memorial Conference October 2006; 28-35. (Watch the Digital Venogram video performed by Amy Rucker, DVM.) Introduction Since 1992 venograms have been used at the International Equine Podiatry Clinic to evaluate horses with lameness problems localized to the foot. This retrograde contrast study can demonstrate structural alterations of the venous as well as arterial supply within the soft tissue and bone early in the course of the disease before the effects of vascular compromise are detected radiographically.1 Venograms have proven to be a valuable tool for making specific diagnosis in horses with foot disease, injuries and diminished horn production. They have been particularly advantageous for treating laminitis as they allow us to identify structural alterations of the solar papillae, lamellar vessels, coronary plexus and terminal arch that can not be seen with other imaging techniques. This has allowed us to follow progressive deterioration of the disease in cases that otherwise might have been considered clinically stable. Before venogram imaging, radiographs were the only images used routinely to evaluate laminitis and other foot disease syndromes. As a result, veterinarians have been limited to evaluating the significance and severity of the disease during the acute phase, meaning the greatest window of response cannot be effectively utilized. A large majority of cases with significant insult deteriorate, ultimately leaving the horse crippled or resulting in euthanasia. Venograms have added to our knowledge of laminitis and other common foot problems, in large part because for the first time we can see the structural components of the vascular supply to the horse's foot. This procedure is relatively easy, uses basic radiographic equipment and can be performed on the standing horse. Equipment and Technique The equipment used at IEPC is a 100/30 MinXray portable unit, asymmetric 6/12 screens, ultra detail film and a 6:1, 106 line/in grid. Several contrast mediums have been used in the past, however we have found that higher concentration produces slightly more information. Reno-60® has been the contrast of choice for the past several years. A variety of catheters have been used. The 21-gauge butterfly is easy to use, easily procured and provides a consistent means of delivering contrast. Sedation of the horse, local analgesia of the foot and a tourniquet placed over the fetlock is required. The original venogram technique developed at IEPC was a collaboration with Dr. Chris Pollitt using his previous in vitro study model and has since been published with minor modifications.2 The imaging sequence that has been routinely used is soft tissue lateral, lateral with grid, DP with grid, DP with soft tissue detail, followed by a soft tissue lateral. The procedure is technique sensitive in large part because the sequence of film must be taken within a time frame of 45 seconds following contrast injection. Tissue contrast injected retrograde into the palmar vein is quickly absorbed into the interstitial space, significantly reducing the value of the information obtained. The soft tissue lateral images have proven to be especially valuable because they allow us to see coronary papillae, circumflex vessels, solar papillae and acute and chronic lamellar leakage. The grid used with the higher MAS has proven to be a reliable means of imaging the terminal arch and its tributaries. The soft tissue and hard penetration grid views were implemented to allow us to evaluate normal vascular anatomy and structural alterations within the soft tissues and bone. The soft DP view allows us to evaluate the medial and lateral coronary supply and the medial and lateral circumflex network. The grid view offers further information concerning the terminal arch and tributaries. The soft tissue lateral view taken at the end of the sequence was implemented to allow for adequate filling time required to consistently image lamellar leakage, decreasing the possibility of missing significant structural alterations. More specific beam selection is required to image vascular lesions associated with White Line Disease and Keratomas. Techniques for imaging the equine foot will continue to evolve with increasing experience performing venograms. Tourniquet failure and perivascular injections are frequent complications encountered in the infancy of procedural skill development. Both complications result in underperfusion and can lead to grossly inaccurate interpretation and misuse of the information. Technique underperfusion should not be confused with stark loss of contrast caused by pathological vascular compromise. The distinction should be well understood before deciding the fate of a laminitic horse based on the information gathered from this valuable tool. Technique 1) Sedate the horse. 2) Block the feet just above the fetlock. Use only 4-6cc of blocking agent to prevent transient edema. 3) Place the horse's feet on proper positioning blocks. This will insure a pure lateral projection. 4) Set the x-ray machine in place, and have all the necessary cassettes and grids within arm's reach. 5) Take a scout film with soft-tissue detail, using a barium paste marker on the face of the hoof wall. 6) Wrap 4 inch Elastikon around the fetlock. This will provide an anchor point for the tourniquet and prevent twisting of the skin while applying the tourniquet. 7) Place a tourniquet over the fetlock. Avoid a mid-cannon tourniquet. 8) Catheterize the palmar vein using a 5/8 inch, 21-gauge butterfly catheter. Be careful not to thread the needle to far in to the vein. You risk making a second hole in the vein. 9) 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. 10) Pull the knee forward slightly while injecting the second syringe. The heel should remain flat on the block. This rocking assures lamellar perfusion by unloading the deep digital flexor tendon (DDF) 11) Clamp a hemostat on the catheter. Quickly tape the hemostat to the leg using the loose end of the tape that secures the tourniquet. 12) Take your series of film. All exposures should be taken within 45 seconds. Move quickly. Radiographic Views i) Lateral, soft exposure ii) Lateral, hard exposure with grid iii) DP, hard exposure with grid iv) DP, soft exposure v) Lateral, soft exposure Soft 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 films. Acute and chronic cases will exhibit similar patterns, yet there are distinct differences between the two. 13) Remove the tourniquet and place cotton or gauze over the medial and lateral vessels. Tape in place for 5-10 minutes. Indications A venogram is a discovery experience, offering 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: Laminitis White Line Disease Keratomas Puncture Wounds Sore feet with thin soles and poor quality walls Having performed hundreds of venograms, I have discovered a pattern of a sequence of events that appears to be repeatable in most pathological conditions. Laminitis can progress from mild onset to high-scale case within hours to weeks. Venograms can provide consistent evidence of each stage of the syndrome. 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 65 degree, DP reveals another perspective when looking at the circumflex vessel and papillae, but this view is not vital for assessing the damage caused by displacement. Interpretation of the Normal Foot Lateral View 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 papillae are clearly seen penetrating the sole proper. The papillae 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. Conversely, the thin soled horse has a compressed palmar vascular supply, though it appears quite different from compression caused by medial displacement. 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 papillae may not be visible or they are very short relative to their normal length. The major vessels are compressed tightly between the bone and hoof wall. When the papillae are demonstrable they have their normal linear relationship with the solar corium. This may be one explanation for 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 5mm 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 papillae. A healthy sole (20mm) will have longer papillae than a sole that is only 15mm in depth. This may explain why a long foot will bleed much easier. When trimmed short there is a very thin foot that has half the sole depth it needs. 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 nutrient foramen than that found in a low-heeled, thin-soled 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. The bone no longer has a chance for survival when the terminal arch loses its function. DP View 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. Some normal horses have medial listing that apparently compromises the growth centers of the medial horn wall and medial sole, as most will have minimal horn growth in this area. Most sinkers will list to the medial side, which compresses the coronary supply and the circumflex zone. As 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 fetlock 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. Early studies 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 vascular space void of contrast 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 muscular spasms along the entirety of the vessels. Reasons for Technique Failure Tourniquet leak Perivascular injection Failure to inject the contrast in a timely fashion Failure to take all necessary views in 45 seconds Horse steps off of the blocks, pulling the catheter Forgetting to rock the leg to allow for total perfusion of the dorsal vessels Removing the catheter prior to taking radiographs Inadequate nerve block 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 papillae 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 Front Horn-Lamellar (H.L.) Zone = 15mm/15mm Sole Depth (SD) = 20mm Palmar Angle (PA) = 5 degrees Bone Angle = 50 degrees Coronary Band-Extensor Process (CE) = 8mm Digital Breakover (DB) = 25mm Adding the bone angle of 50 degrees to the palmar angle of 5 degrees means the hoof angle is 55 degrees. The opposite foot is slightly mismatched with the following measurements: Right Front Horn-Lamellar (HL) Zone = 15mm/13mm Sole Depth (SD) = 16mm Palmar Angle (PA) = 1 degree Bone Angle (BA) = 48 degrees Coronary Band-Extensor Process (CE) = 15mm Digital Breakover (DB) = 30mm One would suspect the hoof angle to be 49 degrees, but with the toe backed up hard (note the 15/13 HL measurement), it can actually measure up to 52 degrees. 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 papillae patterns along the palmar surface. The papillae 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 papillae will be bent forward due to the download and caudal displacement. 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 papillae 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 papillae 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 due to excessive internal heel loading. 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 should be the primary concern of the vet/farrier team. A mild onset may simply alter the direction of the papillae, but this is very significant. It demands immediate mechanical therapy to reverse the forces at play. Interpreting Mid-Scale Damage The mid-scale case will have an increasing HL zone from the onset. This zone will increase several millimeters before displacement occurs. Closely monitor the HL zone! The circumflex vessel appears compressed tightly against the palmar surface of PIII. The venograms taken at onset become very valuable as you track the progress or deterioration of the case. They also allow you to evaluate the efficiency of the selected treatment protocol. Let's look at the racehorse as an example. Many times these athletes have only 6mm of sole depth, a -2 degrees to -3 degrees PA, and very upright pasterns. 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 due to displacement, the horse is normally very lame, as the coffin bone is cutting through the sole corium. The result leaves the circumflex vessel between the wall and the palmar rim. At this stage, the vessels become dysfunctional, and the palmar rim of PIII begins to break down as a result of inadequate nutrient supply. Some acute cases will have 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 on mid-scale cases. 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. All efforts should be made to mechanically unload the compromised zone. The sooner this is accomplished, the better chance the thin palmar rim will remain viable. A favorable response will have an improved vascular pattern within a few days. If the horse appears clinically stable but the vascular pattern continues to deteriorate, derotation shoeing followed by a DDF tenotomy is a preferred treatment. Interpreting 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 approximate the distance the CE has increased. High-scale cases require aggressive therapy, in addition to derotation shoeing and decompression of affected areas. A DDF tenotomy is almost 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 also be absent in this area. Occasionally, there will be a very similar picture along the dorsal vessels. When there is no contrast in these specific zones, I decompress these areas by performing an aggressive wall ablation, pin cast for support and a treatment protocol compatible with new hoof replacement. 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 can 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 have 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 and use the venogram as a valuable prognostic tool. Successful treatment of laminitis requires following: 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. Conclusion Venograms are a valuable imaging modality for horses with clinical signs of laminitis and other problems localized to the foot. They have allowed us to differentiate pathological vascular lesions from the normal vascular tree and visualize vascular compromise before significant digital displacement can be detected radiographically. When used as a damage indicator, venograms allow us to make more timely decisions concerning treatment. During treatment, venogram imaging can be used to evaluate the correlation between various mechanical treatment protocol concepts and the vascular supply to the vital anatomical areas. They are a valuable prognostic tool that can enhance timely treatment decisions, allude to the duration of long term recovery, and confirm irreversible vascular collapse of the digit. Forces that create tensile and sheer strain on the laminae and compressive forces on the sole corium and palmar rim of the coffin bone most probably contribute to the mechanical phase of laminitis that causes a vicious cycle compartmental syndrome. Venogram evidence supports both the concept that DDF forces on the laminae, sole corium and palmar rim contribute to development of the secondary compartmental syndrome and the treatment concept that significantly reducing the tension on the DDF relative to the PA, degree and location of vascular compromise and degree of capsular displacement is an effective treatment in most horses with laminitis. Venograms may confirm cases in the predramal stage of laminitis and distinguish them from cases with similar clinical signs. In the future, accurate assessment of the effects of laminitis, especially in acute cases, before radiographic displacement develops may require venogram imaging. References Redden RF. The use of venograms as a diagnostic tool, in Proceedings. 7th Bluegrass Laminitis Symposium, 1993; 1-6. Redden RF. A technique for performing digital venography in the standing horse. Equine Vet Educ 2001; 172-178.