May  2000

Contracted Feet

by HEATHER THOMAS

Contracted heels and contracted feet have been traditionally classified as an unsoundness in a horse. Even if he's not lame, this condition makes him more likely to become lame, due to the inability of the foot to properly absorb and dissipate concussion. This makes him more susceptible to problems such as navicular disease, or concussion-related breakdowns in other structures of the foot and leg.

A contracted foot is more narrow than normal, especially at the heels and quarters, and the frog becomes small and atrophied, shrinking up to where it no longer has any contact with the ground. Contraction is more common in front feet than in the hind, especially if the condition is due to improper shoeing. Sometimes only one foot becomes contracted, due to injury and lameness, and subsequent disuse of that foot. Front feet are normally quite round, and hind feet a little more narrow and concave at the sole, but it is easy to tell the difference between a normal foot and a contracted one. The normal foot has a healthy frog and heels. The heels of a contracted foot are too close together.

Some breeds have feet that are more oval than round, but the feet are not contracted. The construction and health of the heels, bars, sole and frog can help a horseman tell the difference between a normal, healthy narrow foot and a contracted one. In some horses, one front foot is more narrow than the other as an inherited condition, and it may or may not cause any problems.

Causes: The true contracted foot is an abnormal and pathological condition in which many of the important structures of the foot have suffered degenerative changes. Contracted heels can be due to injury, disuse of the foot and lack of frog pressure, or can be the result of improper shoeing that does not allow the heel and quarters to expand when weight is placed on the foot. Leaving shoes on too long, with the hoof wall growing exceedingly long (especially if the toes grow long and the heels are underrun) and inhibiting proper hoof expansion at the heel and quarters, or keeping a horse shod all year round and never letting the foot function more naturally, are all factors that can contribute to foot contraction especially if shoeing does not allow for proper heel expansion. Shoes should always be just a little wider than the hoof at the heels.

Horses with feet too small for their body weight, or horses with very dry feet, seem more susceptible to contracted feet, just because they lack the size (or the resilience and elasticity, in the case of dry feet) for optimum foot expansion and pumping action (the frog pressure and foot expansion that exerts a push on the digital cushion inside the hoof, helping send the blood back up the leg and aiding circulation within the foot). Excessive dryness of the foot, especially in horses that have been moved from moist pastures to dry paddocks, may lead to contraction of the feet during hot weather.

Lameness may make a horse favor a foot in such a way that he puts less weight on heel and frog, and if he is lame for very long, this lack of weight bearing and proper foot expansion can result in contraction. Once a foot is badly contracted, it may take several special shoeings or even a year of time to become normal again.

Foot expansion is essential to the health of the foot. The hoof is actually a very pliable and elastic structure, compressing its height and expanding in width-especially at the ground surface-each time the foot takes weight. Contraction is a result of breakdown in the shock absorbing mechanisms of the foot; the hoof has lost its ability to expand and it becomes smaller. It's a vicious cycle; once contraction gets started, the foot function (especially in the heel area) is badly impaired and the condition just becomes worse.

Foot contraction is usually accompanied by a dished or concave sole. The foot no longer flattens when weight is placed on it, since the heels cannot expand. The sole becomes more arched upward. If contraction becomes severe, the hoof wall may start to press against the third phalanx (coffin bone) inside the foot, making the horse lame and unsound, a condition that horseman often call "hoof bound".

A contracted foot is narrower than normal, especially at the heel, with the frog small and atrophied. Foot size of both fronts should be compared, keeping in mind that some conditions (such as poor shoeing or navicular syndrome in both feet) can cause contraction in both. The frog is often an inch or more above the ground, and thrush may be present in the unhealthy, small frog. Heels may be so narrow and close together that the bars of the foot touch one another.

Disuse of these vital foot structures eventually leads to an unhealthy condition. The sole and frog, and even the hoof wall, may become very hard and dry, with no elasticity at all, becoming difficult to trim. The hoof wall tends to crack and break or shatter when trimming is attempted. The coffin bone inside the foot may become deformed and no longer circular in shape. The digital cushion above the frog tends to shrink and atrophy, becoming less resilient, interfering with its protective buffering action for the deep flexor tendon and navicular bone, so these structures may also suffer.

Treatment and Correction: Corrective trimming and shoeing can often reverse the contraction process, but the primary cause should be discovered and corrected (such as lameness, improper shoeing, or dry feet). If feet are hard and dry, efforts should be made to help restore moisture to the hoof.

In the past, most treatments for contracted heels were based on the assumption that frog pressure was required to expand the heels and pump blood from the foot, and the main goal in correcting contraction was to restore frog pressure. Standard treatment was to allow the horse to go barefoot, with feet trimmed often-to try to get more frog pressure-or using tip shoes that covered only the toe area, or special bar shoes or T shoes to induce frog pressure when the horse put weight on the foot.

In recent years, with a better understanding of how the foot works, horsemen and farriers have learned that frog pressure is not necessary for producing expansion of the heels and quarters. Weight-bearing alone creates an outward force that expands the hoof wall. If the foot experiences proper weight bearing (on a properly balanced foot), the heels won't contract. Common causes of contraction are improper conformation of the foot (as some horses are born with), lameness that discourages a horse from properly using the foot, or poor shoeing (or trimming) that leaves the foot unbalanced. A major cause of contracted heels is long, untrimmed feet. This alters the proper expansion of the heel and quarters and can also lead to small, atrophied frogs. The same thing can happen when a horse is trimmed or shod with the toes too long.

With proper trimming and shoeing, allowing for heel expansion and weight bearing, most contracted feet will expand back to their natural shape within a few shoeings. If the horse has navicular syndrome and the feet have contracted from disuse due to the pain (reluctance to put weight on the heels because of increased pain in that area), the feet can usually be helped by elevating the heel rather than lowering it, rolling the toe to encourage faster breakover, and protecting the surface of the frog so there will be no weight-bearing in this most painful spot. If the pain can be decreased enough so the horse will bear weight more normally on the foot again, the contracted heels tend to expand.

It was also thought for many years that a full bar shoe would prevent heel expansion, but this is not necessarily true. A bar shoe can be used to protect the frog and heel area (to prevent weight bearing and decrease the pain in a horse with navicular syndrome, for instance) but still allow hoof expansion, especially if the nails are placed so that the heel and quarters can still move outward when the horse puts weight on the foot.

The best way to treat contracted heels is to identify the original cause and deal with it, while at the same time enabling the foot to expand at the heel when weight is placed on it-with proper trimming and shoeing. In most horses, balancing the foot and correcting any deviation from normal foot angle (broken angle such as having the toe too long or the heel too long) will suffice, especially if the shoe can be fitted so it's slightly wider than the foot at the heel and quarters (to allow for hoof expansion) and the last nail placed ahead of the bend of the quarters so as not to inhibit expansion. If the horse has a long toe and underrun heel, the same shoeing principles apply, along with shortening the toe as much as possible and leaving the heels as long as possible, giving more support to the rear of the foot, such as with an egg-bar (full circle) shoe. A good farrier can do a lot to alleviate contracted heels, and over time most cases can be corrected.

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