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:

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 with the most damage.

Rotation
The proverbial degree of rotation can be used as an indicator so long as we don't get too carried away. I seldom attempt to measure the degree of capsular rotation because it is a bit meaningless and quite arbitrary. There are not many feet with perfectly straight walls from the coronary band to the toe, and none have a straight-faced coffin bone.

For many years we have been taught that rasping the rotation away is a helpful adjunct to treatment. I don't believe this philosophy and find no validity in removing the angle of capsular rotation. This is erroneously considered derotation and only serves to weaken the anterior arch of horn. But for the sake of describing parameter variations, we will use the broad brackets of 5,10 or15 degrees as a means to describe rotation within the active rotating cases (not chronic, long term cases).

Sinking
We must be careful describing the 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 20mm 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 radiopaque paste points starting at the hard horn of the coronary band produces a very distinct marker for tracking the descending coffin bone; especially sinkers.

Sole depth
This is measured directly beneath PIII to the top surface of the shoe or ground marker on the barefoot horse. Be as accurate as possible when measuring sole depth. Make certain the primary x-ray 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 sagital cut.

Performance Thoroughbreds and Quarter Horses often are found with less than 10mm of sole. They are not typically sound, but they often remain competitive. Their sole depth can decrease to 3-5mm and seem to survive, whereas a horse with 15-20mm of sole that is compressed to 3-4 mm is in serious jeopardy. Laminitic Warmblood horses with 20-25mm of sole compressed to 15mm are seriously compromised and soon develop into high-scale cases. Therefore, the start model is once again part of the assessment.

Considering the sole depth in relation to the extensor process measurement can be helpful. If comparative films show that there is very little sole, less than 10mm, with no change in the CE, you have what I refer to as the "Belotta Syndrome." The foot has simply been rasped off. The sole was thinned since the last film was made. The palmar distance makes it appear like a sinker, but the parameter at the extensor process has not changed.

This is a very significant finding on a bilaterally lame horse that clinically present very laminitic. What you have is a horse whose foot was simply trimmed inside the comfort zone.

Palmar Angle
The 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. It is typically either a negative or positive measurement.

A club foot naturally has a much higher palmar angle than the opposite foot. Ponies, mules and many others with very upright feet have a strong palmar angle (15-20 degrees). This 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.

The range of normal varies somewhat even among light breeds. Light breeds with healthy, strong feet normally have between 3- 5 degrees in the front and slightly higher angles in the hind feet. Many Mustangs will be flat (zero), while most domestic horses that are zero have crushed their heels and 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 digital flexor (DDF) tendon. As the digit rotates around PIII, the palmar angle increases. In very chronic cases, there may be 15-20 degrees palmar angle and 30-40 degrees capsular rotation.

Racehorses with a negative 5 degree 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 parameters for the podiatrist, as it offers direct insight to the force of the DDF and many options that can significantly influence these forces.

Having said that, let's describe a high scale case of laminitis:

• Grade 2 club
• HL 18/22 mm
• Hoof Angle 60 degrees
• Palmar Angle 5 degrees
• Sole Depth 2mm with sole sagging below the shoe
• Grade 2 bone disease (a venogram would finalize this assessment)

• Hoof Angle 50 degrees
• Palmar Angle <5 degrees
• HL 17/17
• Digital Breakover 50mm
• CE 15mm.

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. If you can see it, the opaque zones will help determine this.

Ten degrees is too much displacement, though, for a mid-scale club. Possibly a few recurrent abscesses have thickened the HL zone. How do we know where he is in the syndrome?

Comparative films, coupled with clinical signs, are helpful but may require 3-10 days to pick up any subtle changes. Secondly, a venogram can be extremely helpful when trying to determine how old a displacement lesion may be. Acute lamellar tears have a very characteristic pattern, as do old scars. Remodeled circumflex vessels also appear totally different than acute prolapsed vessels. I encourage any podiatrist to learn this technique. Use healthy animals to gain confidence, competence and a basic range of normal.

Lucent Areas
Gas density lesions can be in many areas of the digit and for very specific reasons. 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 because 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 occur just within the stratum medium along the ectodermal lamellar layer. This air dense zone is thought to be nitrous oxide resulting from 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 abruptly at the inner sole margin. Even in cases 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. Instead, it is 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. The terminal laminae are most visible in white line cases because the sole has migrated at the outer margin of the wall. This is the first clue that pathology has occurred.

There is little to 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. The sides of the lesion are very irregular in shape and the apex of the lesion is often pointed with 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. 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. Recognizing the stark differences is of the utmost importance.

A closer look at white line disease often reveals dirt, small stones and sand within the horn wall that entered along the deficit at the ground surface. The weight of the horse closes this flap when loaded creating a one-way valve effect. Once the very vulnerable ectodermal laminae become severely compressed by this space occupying foreign body, the horse shows signs of pain.

Regardless, most all cases remain quite sound well after radiographic lesions are well established. Again, this is a totally different picture than that found with laminitis.

Sub solar lucencies occur 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 within the sole layer as new horn is laid down at the inner face. It is often thought that many sub solar lucencies are abscesses and must be opened. The contrary is more often 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 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 incredibly high-scale. The moist, subtle separations that have slight serosanguineous drainage are potentially lethal, too. Conversely, the coronary band with dry separation looks scary, but it seldom causes problems. Likewise, small suppurative ruptures seldom create a serious threat. I do not rate them but take note of where and how frequent they appear. They should go into your data bank as an aid when preparing a treatment program.

Venograms
This procedure is technique sensitive, but it 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. First, time is of essence. The bet films are taken within 30 to 45 seconds following injection of the contrast medium. I like to take 4 to 6 views within this time frame. You must work efficiently because 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 in this procedure 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: