Today on Texas Vet News I am going to talk about one of the most common causes of hind limb lamenessin horses, and that is arthritis of the hock. Dr. Jay Bickers from Stephenville indicates the hock consists of ten bones and five joints so it is a fairly complex joint. However, the major source of problems in horses is found in the lowest three joints, which actually don’t move much; their function is mostly to absorb shock. Inflammation and arthritis in these joints is thought to be caused by shear forces and twisting of the joint as the horse performs high speed maneuvers. The subsequent pain causes the horse to bear less weight on the leg and when moving. Affected horses will show decreased forward movement of the leg and a decreased height of movement. Also, when viewed from the rear, the back legs of a horse with distal hock joint arthritis appears to land more toward the midline of the horse than normal.

Diagnosis of mild arthritis can be difficult as there may not be any lameness and the only clinical sign may be decreased performance, such as when a barrel horse may not want to turn a barrel or a roping horse may not want to stop. Injecting a local anesthetic into the joints will block the pain and if the horse moves better after the injection that can help the vet know this is the problem area. Also, all horses with problem in this area should be x-rayed to make sure there are no fractures causing the problem. Treatment of the condition involves the use of pain relievers such as phenylbutazone if symptoms are mild and joint injections with cortisone as the disease progresses. Some of the more severe cases require surgery to fuse the joints together to decrease pain.