Accessory carpal bone displacement in two dogs

The diagnosis and treatment of luxation of the accessory carpal bone in a racing greyhound, and subluxation of the same bone in a lurcher, are described. The injury in the lurcher occurred in both carpi, but on separate occasions. Both dogs had severe thoracic limb lameness with marked carpal swelling. The diagnosis of luxation was obvious from carpal radiographs. The subluxations were difficult to detect on palpation, but were suspected and confirmed on exploratory surgery, which showed an avulsion of the lateral support structures of the accessory carpal bone from the distal ulna. Pancarpal arthrodesis with accessory carpal bone excision undertaken in the greyhound was successful. Following repair of the torn ligaments, the lurcher returned to full activity without lameness before sustaining the same injury to the other carpus. The anatomy of the accessory carpal support structures and the aetiology of the injuries are discussed.