Osteoarthritis of the tarsocrural joint may be seen as a primary disease or develop secondary to trauma, osteochondrosis, or osteoarthritis of the distal hock joints. It is usually associated with joint effusion. Lameness may vary from mild to severe and is usually improved by intra-articular analgesia of the tarsocrural joint. In horses with primary osteoarthritis of the tarsocrural joint, often no radiologic abnormalities are evident, and diagnosis is based on arthroscopic examination. Response to intra-articular medication with corticosteroids and hyaluronan is often disappointing, and prognosis for return to athletic soundness is guarded to poor.