Stump Foot (“Club Foot”) in Horses – Last Word

by
James Rooney, D.V.M.

This essay is a continuation of and, I hope, the last word on my studies of this condition in horses. The paper will or has already appeared in the American Farriers Journal.

There is an abundant, if not very helpful, literature on the web and elsewhere on so-called “club foot” in horses. I say so-called because the condition in the horse is quite different than that dubbed club foot in humans. I prefer the term stump foot after the German: stelzfuss.

I am considering here only that condition which occurs primarily though not exclusively in the right front foot, involves shortening of the deep flexor tendon with an increased hoof angle (high heels), and a tendency for the animal to “stand back” with the affected leg.

My earlier work and analysis of this condition can be found on this web site and listed in the bibliography. The present paper elaborates on and, I believe, completes that earlier work, and the conclusions presented in the present paper may be considered with the findings of that earlier work.

It is quite clear that stump foot is a shortening of the deep flexor tendon. The tendon is not contracted because tendons do not and cannot contract; in fact, it is a shortening of the deep flexor tendon toward its normal rest length. The rest length is that length when there is no tension, strain in the tendon.

The first and most significant contribution to understanding this condition was that of Owen
(1976). He observed that stump foot could appear in foals kept up in boxes (stalls) during inclement weather and attributed that to incessant pawing by the confined and bored foals. Such pawing tends to wear down the toe, allowing the heels to grow out. It is obvious that as the height of the heels increase there is less tension in the deep flexor tendon. Less tension, of course, means that the deep flexor shortens.

The conditions described by Owen certainly do not pertain to most cases of stump foot. His observations, however, provide the essential information needed to understand this condition.

It has often been observed that many, if not most, modern horses stand with one foreleg back, under the body, when grazing. Such a position entails more open coffin and fetlock joints which, in turn, allows shortening of the deep flexor tendon.

The questions, then, are why do horses stand this way when grazing and why should it be the right foreleg which stands back more often? The first answer is quite simple: since the evolution of the horse came under the partial control of man, there has been a rapid and significant increase in the height of horses of many breeds. This increase has been largely the result of selection for longer cannon bones. Because of this height increase, many horses must put one foreleg back in order to reach the ground to graze. This entails less body weight on the standing back leg and, so, less tension in the deep flexor and, so, shortening of the tendon.

The second question, why the right foreleg, is more difficult and problematic. It is well-known that most horses prefer to turn to the left, the near side. While there is argument on reasons for this, it is my contention that this is an inherent trait. (Please see the essay Handedness in Horses on the web site.) Further, I speculate that this is the case because the normal proprioceptive perception of the horse is of greater stability with the left foreleg stiffening and supporting as it turns. Taking all that as plausible, if not proven, the grazing animal would “feel” more stable with the left foreleg in support.

One is quite justified at this point to ask why not stump foot in all horses which have increased in height at the hand of man? Such questions are impossible to answer for every possible case. Not all horses are left handed; not all are so tall that they must stand back in order to graze; some, such as Standardbreds, receive such careful attention to their feet that incipient stump feet do not develop. The reader can, I am sure, think of others.

In the earlier web site essay I described the thinner, weaker extensor branches of the suspensory ligament as characteristic of the stump foot. It is clear enough, now, that these attenuated branches must be secondary and caused by the rotation of the hoof caused by the shortening deep flexor tendon.

How does one deal with the stump foot once it is present? In brief, the mechanics of the foot strongly suggest: (1) that the heels should be lowered (hoof angle decreased) successively and judiciously and (2) the toe of the shoe should be extended beyond the edge of the hoof wall - again, judiciously and not so far as to cause stumbling or interference. There are good mechanical reasons for both of these actions.

Caveat: It is obvious that I have made several assumptions in this paper which are not supported by hard fact. What I have done is to construct an hypothesis for stump foot based on such hard facts as are available together with reasonable assumptions where hard facts are not available.

Bibliography

www.horseshoes.com/farrierssites/sites/rooney/clubfoot/clubfoot.htm

Owen J M (1975) Abnormal flexion of the corono-pedal joint of “contracted tendons” in unweaned foals. Equine Veterinary Journal 7: 40-5

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