Shoeing for natural balance

Abstract

Trimming and shoeing for so-called “natural balance” is controversial but is gaining acceptance among many trainers and horse owners. Tradition dies hard. The concepts involved with trimming for natural balance goes against most of what has been taught in veterinary and farrier schools for many years. Eugene D. Ovnicek, a Registered Journeyman Farrier from Penrose, CO, has been a leading proponent for the new concepts in trimming and shoeing. He claims that the principles of “natural balance” are an accumulation of common sense ideas about hoof care. He argues that these ideas have been supported anecdotally and are beginning to be supported by scientific scrutiny. An example of this is the refereed paper by Page and Hagen in the JEVS 22(6):258-264, 2002. Farrier Ovnicek has teamed up with Dr. Page, a Colorado equine practitioner, and Dr. R. M. Bowker, an anatomist at Michigan State University. The common denominator binding these 3 in their descriptions of “natural balance” of the equine foot is studies of wild horse feet. Ovnicek says, “Our objective is to inform the hoof care community about some of our new findings so that hopefully better choices can be made in general foot maintenance and the treatment of certain lameness problems.” Last year Ovnicek was invited to speak at the American College of Veterinary Surgeon’s Veterinary Symposium, in Chicago, IL. He said, “There are several traditional thoughts about the foot that need to be looked at more closely. For instance, we have long believed that the pastern should be in line with the dorsal hoof wall. If this were so, the phalanges would be in line as well. Medial/ lateral (M/L) balance is attained by using the cannon bone, pastern and heel bulbs as a guide. In addition, dirt should be cleaned regularly from the foot to prevent thrush and stone bruises. It is thought that the hoof wall is designed to bear the weight of the animal. Most of the past research has been directed with these concepts in mind. It is also accepted by most practitioners that all horses should land flat from both a M/L and A/P plane.” “Recent research information has forced us to rethink many of these traditional concepts. Common sense questions often inspire common sense answers. For example: Why do the quarters always break away before the toe and heel? What does a flare mean to the foot? Does P-3 (coffin bone) always maintain a parallel relationship to the hoof wall? Why is there a small patch of callused frog at the apex, as well as a prominent buildup of frog at the buttress that is usually callused and harder than the mid portion of the frog? Both of these portions of the frog are the last to exfoliate and grow back rapidly when they are removed. The frog also produces a lip or ledge of frog on the groundside that extends from the cranial aspect of the central sulcus to and includes the calloused heel bulbs. These are all common findings that exist on all horses, wild or domestic.” He pointed out that the raised area of the sole just inside the hoof wall is easier to see on barefooted horses, but are nevertheless present in all horses. This is shown in Figure 1. He pointed out that the wall will only chip, break, or wear down to this raised part of the sole. When this occurs, the sole in this area becomes hard and calloused, similar to the hoof wall. It is common sense to believe that this calloused part of the sole is meant to bear weight, as occurs in wild horses with no protective shoes. “The purpose of our wild horse study,” he said, “was to see if there were hoof wear patterns that were consistent, unlike many domestic horses that have a wide range of hoof shapes and wear patterns. Arrangements were made with the BLM to examine wild horse feet once these horses were in lateral recumbency. We found each foot packed with dirt in the caudal region of the foot, around the frog and bars. The distance from the frog apex to the wall at the toe was always shorter than what we commonly see with domestic feet that are shod. It is common for domestic hooves to have a wide range of distances from the frog apex to the edge of the wall at the toe. The frog of domestic horses often becomes distorted and stretched forward as well. The bars on wild horse feet all terminated about 3/4 caudal to the frog apex. The heels were worn back to the frog buttress in one group of horses that lived in a shale, granite and sandstone environment. Others who lived in softer, less abrasive terrain had longer heels that would press into the sand instead of being worn away, very much like domestic horses in similar environments. All horses had a small enlargement of frog at the buttress and apex that was calloused, showing signs of weight bearing, again very much like what we see on domestic horses.” To determine the primary natural contact points of the bottom of the foot, dirt was removed from the bottom of the wild horse foot. A flat board was freshly painted and rubbed over the bottom of the foot. Paint was therefore smeared on the high points on the groundside of the foot. There were 4 primary contact points seen on every foot examined. These were at the medial/lateral toe quarters and on each heal. To determine the point of breakover in these wild horse feet, they drew a line across the foot at the cranial edge of the paint marks at the toe quarters. A line was also drawn from the toe quarter marks to the diagonal heel marks. This is shown in Figure 2. “Data from the wild horse studies opened the door to many questions about our traditional thoughts on hoof anatomy and function, not to mention nutrition, lifestyle and genetics,” continued Ovnicek. “One of the tools we gained from the wild horse research was the ability to more easily recognize hoof deformity. By simply evaluating the foot from the bottom using a line drawn across the foot at its widest point (approximately 3/4 to 1 behind the frog apex, where the bars terminate) allows us to see if there is more ground surface mass ahead of or behind the centerline. Horses that stumble, forge, interfere and land toe first will have more ground surface mass ahead of the widest part of the foot.” The wild horse studies have shown that when a foot is routinely trimmed too close at the toe each time the horse is shod, P-3 seems to settle some, and the horse can be “off” for a few days. Ovnicek and his colleagues believe that the sole ridge, or callus, plays a major role in supporting P-3. This is an important new concept that leads to the conclusion that when this sole callus is overtrimmed the laminae attachment of P-3 at the distal border may be compromised. This will allow the hoof wall to migrate forward, as it does in laminitis. The damage can be seen in the vertical deformity in the hoof wall at the hairline Ovnicek said, “Slight heel first landing is common with feral horses as well as sound domestic horses; therefore, we find it to be optimal for Natural Balance principles. Research has shown proprioceptors in the callused portion of the frog buttress! This supports and suggests that heel first contact may be important. Later research of Dr. Pages showed that when the breakover was placed 1/4 ahead of the tip of P-3 and the heels were trimmed so the frog buttress had contact with the ground, pastern alignment improved and the navicular bone became more vertical. These combined hoof preparation techniques will routinely initiate a heel first landing. In retrospect, this will help to avoid stumbling, forging, interfering and has shown to improve hoof deformities that lead to heel soreness, contracted heels and navicular disease tendencies.” Figure 1.