04/06/2014 2:02PM

Managing racehorses' feet can lead to optimum performance

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By Denise Steffanus

The ideal racehorse foot, as presented in textbook illustrations, rarely occurs in nature. Each foot, even on the same horse, is influenced by a number of variables, including the horse’s conformation, the structure of the individual leg, moisture content of the hoof components, and athletic demands.

“Feet all have different mechanical requirements that need to be met in order to remain healthy and functional enough to withstand the rigors of training,” said Dr. Ric Redden, founder of the International Equine Podiatry Center in Versailles, Ky. “The key to managing Thoroughbred feet is having a good working knowledge of what we are managing, what they need to be healthy, and how to make it happen. A good time to assess what we are managing is when the yearling or 2-year-old arrives at the training barn.”

Examining the foot

Simply observing external features of the horse’s foot is not enough. Farriers must know what is going on inside that foot, Redden said. Learning to read and interpret information on radiographs can help farriers better understand how to protect the health of the foot. 

No two feet are identical, even on the same horse. For each individual foot, information on radiographs reveals the unique characteristics of the coffin bone (the main bone in the foot), its relationship to the hoof capsule, and the relationship of both with the ground.

“What we see when we look at the outside of the foot is the product of internal forces that regulate growth zones in the sole, the wall, and the frog,” Redden said. “These forces constantly change with the amount of growth, the wear and stress of training, excessive moisture, the effects of trimming, shoeing, hours of inactivity, and injury and disease that may be present or chronic and leave scars and weakened areas that can pose soundness issues.”

In addition to radiographs, Redden suggested using venograms, which show blood flow to the vital growth centers of the foot, as another valuable tool. Together, both modalities provide an efficient means of planning a management protocol tailored to meet the immediate and long-term requirements of each foot.

The heel-crush cycle

How the foot responds to training and speed is related to the overall strength and health of the foot, as well as many variables that can affect its integrity.

A front foot with a lower profile normally deteriorates very quickly, as does the opposite hind foot. The side of the shoe against the foot begins to show wear, and a close look at the foot reveals excessively worn and frayed heel tubules, columns of tissue that comprise the hoof wall. Crushed heels plague Thoroughbred racehorses.

“This is not a problem with your farrier. This is a problem for your farrier,” Redden emphasized. “Without radiographic information to direct the rasp and determine shoeing protocol, most farriers opt for a wedge pad and/or shoe, which offers immediate improvement and some semblance of balance – the toe-to-heel ratio. This looks great and works well for a few days, but the internal parameters causing the heel crush have not been altered, so the cycle continues. By the time the reset comes around, the heels are folding under and forward, and the frog now hangs below the wall surface.”

As the heel continues to deteriorate, the toe appears very long in comparison. Accepted practice is to “back the toe up” (rasping the face of the foot to create a larger toe angle), which only creates the illusion the heel has improved. This actually causes the healthy wall to lose thickness and the foot to become even weaker.

“As the heels lose strength, the wings of the coffin bone begin to drop as the apex starts tipping upward,” Redden said. “The digital cushion, which also supports the back of the foot and acts as a major shock absorber, begins to crush, allowing further dropping of the wings, creating a negative palmar/plantar angle [the angle found between the palmar surface of the bone (bottom) and the ground surface]. The more the heels are artificially pushed up, the more crush occurs. These changes create a prime environment for internal bruising, soreness, pain, quarter cracks, and numerous compensating issues.”

Management

The key to a healthy foot is mass. Even a well-balanced foot can be at risk for injury if it does not have mass to protect its sensitive underlying structures.

“Our task is to detect the weak areas early and assess how we can mechanically enhance the natural recovery process, all the while being mindful of internal variations,” Redden said.

A yearling entering training whose feet have been well managed should have a strong hoof capsule with mass and robust heels, whether it is shod or barefoot. When the yearling transitions from mostly turnout to standing in a deeply bedded stall for 23 hours a day, its hoof loses much of its durability because it no longer needs to protect itself by being tough and hard. Then when the yearling is sent out to gallop, its weakened feet heat up from concussion, and the initial response is to pack them in mud to draw out the heat. This begins deterioration of the foot.

“As the heel angle decreases, so does digital cushion mass,” Redden said. “As cushion mass becomes compressed, shock-absorbing abilities are greatly reduced, passing excessive load to the heel tubules, which quickly fold inward and forward. As the heel tubules fold, the bars do likewise.”

The domino effect spreads throughout the hoof structures until soreness plagues the heel and inflammation permeates the entire foot. 

“Quarter bruising followed by a quarter crack often results, along with numerous compensating soft-tissue and bone injuries that can and far too often do cause catastrophic, crippling, or fatal injury,” Redden said.

Preventing hoof deterioration

Keeping the feet dry and tough is the first step. This means not using mud or oily hoof paints.

When trimming, farriers should remove only what is not needed to maintain the integrity of the foot.

“Work off lateral X-rays as often as possible to learn what you have to work with and what you have left,” Redden said. “Avoid nippers. Very little is to be removed. The rasp allows far more flexibility, depending on what we find as we remove excess horn.”

He offered farriers these tips for preparing the foot for shoeing:

◗ Be reasonably certain of the palmar angle and sole depth under the apex. You can only learn this by observing the relationship of external landmarks with radiographic soft-tissue parameters.

◗ Avoid trimming all feet to look alike with a textbook profile. This can drastically disrupt natural balance instead of enhancing it.

◗ Avoid trimming away live sole, bars, and frog before removing wall. This practice encourages removal of more sole than is necessary, which is followed by removing more wall than is necessary.

◗ Avoid trimming from toe to heel in a flat plane when heel crushing is present. This invariably lowers the palmar angle, creating more of the same with each reset.

Redden said farriers and veterinarians are working together more and more, using radiographic information to deal with routine foot issues and to monitor overall foot health.

“The good news is we have the means to do a better job,” Redden said. “We just have to do it differently. Knowledge is powerful, and we must all strive to learn the requirements of the foot to keep it healthy.”