Capped Hock Injury

I have a three-year-old Thoroughbred filly who was shipped from Texas. When she arrived, she had a swelling on her hock that was called a capped hock. What exactly is a capped hock and how should I deal with it? Will it affect her ability to race successfully?



To understand fully what a capped hock is, it is helpful to know something about anatomy. The horse's body, like a human's body, is filled with sacs knows as bursae. These sacs are filled with synovial fluid and are found at points where there are bony protrusions like the hock, or the human elbow. There also is one that lies deeper within the shoulder. These bursae are located at these points to help facilitate the movement of the tendon over that particular angulation. They are, in short, cushioning devices.

A capped hock is merely a distention and inflammation of the bursa that lies at the point of the hock. This is a common injury in all horses, not just Thoroughbreds. It is not anything that develops on its own, but rather is caused by some kind of injury to that particular area.

You say you noticed the swelling after the filly was shipped from Texas. Since a capped hock is usually caused by a trauma to that area, she might have banged her hock during the trip, resulting in what you later saw. Some horses are notorious stall kickers, and it is not unusual to find this injury where this vice exists. As a result of the blow, the bursa becomes "boggy." You can feel it and move it all around. The soft tissue there has swollen and has filled with fluid. This is known as an edema.

Unfortunately, once an area like this has filled with fluid, it is very difficult to get rid of permanently. However, the good news is that, depending on the severity of the blow that caused the initial injury or whether your horse has a tendency to repeat the behaviors that would cause such an injury, a capped hock is usually nothing more than a cosmetic injury. It's 100% a blemish. Although it might not look good, if the trauma were not a severe one, there should be no permanent effect on her performance.

Your filly may immediately subsequent to the injury exhibit some degree of lameness. This condition usually is temporary since a capped hock is not really a lameness problem. However, if other soft tissue structures have been damaged, then there is a likelihood that lameness will occur and treatment should be provided accordingly. Contact your veterinarian and allow him or her to assess the situation and advise you how to deal with the problem effectively.

For mild cases of capped hock where there is some pain, some heat on palpation, and swelling, treatment is geared toward reducing these symptoms. If the injury occurs only once and is mild in nature, the results are reasonably good. First you want to get the heat out. Therefore, the treatment consists of the application of ice, the use of cold hydrotherapy, and the administration of anti-inflammatory medication. These are all short term treatments. There are no long term treatments for this kind of injury.

Since most of the injuries of this nature occur in places that are difficult to bandage, the use of a bandage as a treatment has been arguable. However, the development of new types of bandages like the elasticized support bandage, which provides pressure to the area, might be in order. Again, you need to consult your veterinarian to make sure that bandaging is called for and that the bandage will not do more damage to other support structures in the hock region.

For more severe cases of capped hock, it might be necessary to be more aggressive in the treatment. The swelling might require draining. If there is an open wound and severe inflammation in the bursa and an infection sets in, then the treatment might require the use of antibiotics.

You also might administer corticosteroids. However, there is a danger of complications with the use of these kinds of drugs. Corticosteroids are potent anti-inflammatories and can, therefore, suppress the body's normal response to infection.

Because of the location of the injury (there are many important structures located in this area), the kind of treatment your filly receives is very important. Call your veterinarian and have the injury checked out. If it is a mild case and there is no open wound of any kind, your practitioner probably will recommend hydrotherapy and the administration of a topical inflammatory like DMSO, a systemic inflammatory like phenylbutazone, or merely the use of your poultice of choice.

About the Author

Rhonda Rathgeber, DVM, PhD

Rhonda Rathgeber, DVM, is a partner with Hagyard Equine Medical Institute in Lexington, Ky. She also has a PhD in equine anatomy and locomotion from Washington State University.

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