Radiocarpal and/or middle carpal osteoarthritis in horses typically is characterized by chronic thickening of the joint capsule and decreased range of motion. Posttraumatic severe carpal osteoarthritis is not uncommon in Thoroughbred broodmares after retirement from racing due to career-ending carpal injury. These patients may also have an angular limb deformity as a result of joint instability.
Spontaneous osteoarthritis of the carpometacarpal joint can also occur and has been described mainly in Arabians and Quarter Horses. This condition typically affects the medial aspect of the joint and is characterized by lameness (minimal at first), firm swelling over the medial aspect of the distal carpus, and response to intra-articular analgesia of the middle carpal joint.
Radiographs of carpometacarpal joints with osteoarthritis typically show periarticular new bone proliferation (sometimes marked) over the proximal second and/or third metacarpal bone (see image), lysis and/or sclerosis of the bones surrounding the medial carpometacarpal joint, and loss of the medial joint space.
Courtesy of Dr. Matthew T. Brokken.
Treatment consists of conservative therapy (systemic and/or intra-articular anti-inflammatories), surgical arthrodesis, or facilitated ankylosis. (See also Osteoarthritis in Large Animals.)
In its earlier stages, osteoarthritis of the carpus is managed as it is in other joints—ie, with chondroprotectants, NSAIDs, rest and exercise modification, intra-articular medication, and sometimes surgical debridement.
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Also see pet owner content regarding osteoarthritis (degenerative joint disease) of the carpus in horses.
