On the left is a fairly normal radiograph (X-ray) of a horse’s hock. On the right is a hock demonstrating advanced arthritis. The arrows point to the distal intertarsal joint (DITJ), one of four major joints that comprise the equine hock. Note that on the left, the joint space is well-defined, and the margins of the bones are smooth. On the right, however, the joint space is difficult to make out, and the bones are fuzzy. This is evidence of active remodeling, as the body attempts to respond to stress and inflammation in the joint by laying down more bone, even as other parts of the bone are resorbed.
Interestingly, both horses demonstrate signs of hock soreness, and the radiographic findings do not always correlate to the degree of pain. When enough new bone is laid down, the joint can effectively fuse. This is actually not a bad thing in low-motion joints such as the DITJ, as the lack of bone-on-bone grinding action tends to eliminate pain. Once arthritis is advanced, we sometimes even encourage bony fusion, such as by injecting irritating substances into the joint. This is not a procedure that is taken lightly, as we would prefer to maintain full use of the joint, but there are cases where this is the best way to maintain comfort. The horse on the right is unlikely to respond well to more traditional hock injections with steroids and hyaluronic acid due to the severity of his arthritic changes. Conversely, the horse on the left could likely benefit from anti-inflammatory injections to reduce pain in the joint. (In any case, the benefits and risks of intra-articular therapy should be carefully considered prior to treatment, and we do not encourage “maintenance” injections. On the other hand, joint injections can be an important part of multimodal therapy to keep your horse sound, healthy, and happy.)
At Fox Creek Veterinary Hospital, we offer full lameness examinations, gait evaluations, digital radiography, and therapeutic options to treat soft tissue and joint disorders, including intra-articular therapy, IRAP, and PRP. We also offer chiropractic consultation and oral medications to help with pain and stiffness. Please contact us at 636-458-6569 with any questions about your equine lameness needs.