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).
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, upri