A dressage horse’s soundness is a major concern for any owner, but it’s especially important for those who compete at the highest levels. A slight blemish in the hock area will be heavily penalized by most good dressage judges, and a deteriorating condition may even end a career. With advances in treatment, horses with bone spavin can be returned to rigorous work with minimal restrictions.
Bone spavin is an arthritic condition that affects the two lower joints of the hock (tarsometatarsus). Although these two joints do not move as much as the upper joint, they do experience considerable stress. Consequently, they are more prone to the wear and tear that leads to osteoarthritis. The disease is more common in certain heavier breeds, but conformation, trauma, and injury can also play a role. In its mildest forms, the horse is only intermittently lame. Most horses can warm up out of the stiffness, but as the condition progresses it becomes more consistent and the horse is reluctant to pivot or circle in its favored direction.
X-rays and ultrasound examination can help pinpoint the site of the problem and determine whether or not there is any damage to the soft tissue structures surrounding the joint. The underlying cause of the disease is excessive compression of the cartilage in the two distal tarsal bones (central and third tarsals). Over time, this leads to narrowing of the joint space and a buildup of fluid in the joint. The extra fluid causes pain, and the horse tries to compensate for this pain by putting more weight on the opposite limb.
Treatment for bone spavin is similar to that used in other types of arthritic conditions. Anti-inflammatories and pain relievers can be used, but the most beneficial drugs are corticosteroid injections into the hock joint. These can solve the problem temporarily, but they must be given regularly to continue to be effective. It’s important to check the federation rules to make sure that the drug you choose is permitted in competition. A bisphosphonate such as tiludronic acid, tradenamed Tildren and Equidronate in the UK, has also shown great promise for treating bone spavin.
Bone spavin cannot be cured, but with careful management, most horses can remain active and competing for years. It’s important to keep in mind that if the condition is left untreated, it will progressively get worse and eventually lead to ankylosis of the joint. A change of career for the horse will prolong its life, but it’s important to remember that a horse with ankylosis will never be 100% sound. It may become more suitable for a lighter workload and may be able to return to the level of performance that it was previously doing. Light exercise, however, will be of benefit to all horses, including those with bone spavin. It’s important to discuss all of these issues with your veterinarian. They can help you decide the best course of action for your horse and will provide advice on the best way to keep it as healthy as possible.