Capped Hocks

My horse has suffered from an injury to his hock that my veterinarian called a capped hock. Can you please explain a little more about what a capped hock is, what caused it, and what I can do for it?

Capped hock, also known as bursitis of the hock, is a fairly common ailment that affects all breeds and disciplines of horses equally. This is an acquired bursitis of the hock caused by trauma, which can result from a trailer accident, bumping against a stall wall with the hocks, or any other instance where the hock is bumped and aggravated. The condition is typically noticed as a firm swelling at the point of the hock, and if lameness does occur, it's usually mild, but the blemish may be permanent. The swelling can be extensive and accompanied by an edema, depending on the severity of the trauma.

Due to the nature of the disease, the condition tends to recur and become worse every time it occurs if it's not treated aggressively the first time. If accumulation of the fluid is not reduced in a reasonable period of time, then a subcutaneous bursa or "false" bursa will develop. At this point, once the fluid accumulation has been there for a long period of time, the lining of the subcutaneous sac of the bursa becomes more or less a permanent fixture.

In order to avoid this permanent disfiguration, aggressive treatment should be sought in the acute phase, or the first time a cap-
ped hock is diagnosed.
The treatment consists mainly of anti-inflammatory medication and rest. An injection of corticosteroids to reduce the swelling might also be of benefit at that time. Part of the corticoid solution should be injected into the cavity, and part into the surrounding tissue after the synovial content of the bursa is withdrawn. If necessary, these injections may be repeated several times a week. A pressure bandage should also be used at the point of the hock whenever possible. However, care must be taken when applying the bandage over this difficult area in order to avoid skin sloughing over the Achilles tendon. By treating the capped hock in the acute phase, you avoid the formation of a subcutaneous bursa, which will help prevent disfiguration of the hock.

However, if the condition becomes chronic, it will be very difficult to make the leg look normal. At this point, the only effective treatment is to create drainage. This is usually done with a penrose drain, or some other sort of drain, that is put in the affected area so that second intention healing can occur, which is healing by granulation tissue. When you put a drain in the sac, the sac deflates and that provides time for the skin to reattach in a normal fashion in the subcutaneous area. The skin is then allowed to reattach to the tissue underneath the capped hock, and the space created by the pseudo bursa is eliminated.

If the injury to the hock occurs only once, and the case is treated before extensive fibrosis occurs, the results are reasonably good. However, if the injury is repeated several times, which happens in many cases, and extensive fibrous tissue results, little can be done to correct it. At this point, surgery is an option to remove excess fibrous tissue. However, a larger blemish might be the end result.

It should also be noted that in the acute phase, the simple capped hock should be differentiated from an infectious process that might be associated with a capped hock, which is another issue altogether. For this reason, the horse should be seen by a qualified veterinarian to determine if it's a simple capped hock or a septic (infectious) capped hock, and proper treatment should follow.

About the Author

Michael A. Spirito, DVM

Michael A. Spirito, DVM, is a surgeon at the Hagyard Equine Medical Institute in Lexington, Ky.

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