Osteochondrosis dissecans in a juvenile roan antelope (Hippotragus equinus).

A 4-mo-old, juvenile roan antelope (Hippotragus equinus) presented for an acute and progressive lameness of the left hind limb, which was non-responsive to anti-inflammatory medication. The antelope was anesthetized for examination, radiography, and lab work. The left stifle joint had limited range of motion and was markedly swollen on physical examination. Radiography revealed thin cortices of the left distal femur and proximal tibia, as well as multiple lytic areas in the condyles. Euthanasia was performed due to the severity of the lesions and the animal's overall physical condition. Postmortem findings included a parasitic infection of the gastrointestinal tract. Cartilaginous erosions, associated with fibrotic connective tissue and viscous joint fluid, were identified in all appendicular joints. Perimortem lab work demonstrated anemia and hypoproteinemia. Joint fluid was inflammatory but non-infectious, and aerobic culture of the joint was negative for pathogens. Histologic examination identified focal, transmural necrosis of the articular cartilage with clefting. Osteochondrosis dissecans was diagnosed, which initiated an evaluation of the nutritional status and management of the herd. This is the first documented case of osteochondrosis dissecans in a roan antelope.