Osteoarthritis (degenerative joint disease) is the most common type of chronic arthritis that results from the ongoing breakdown of cartilage. Without cartilage, the bones are no longer cushioned against each other as they move and bear weight. Pain, stiffness and swelling results.

OA is very common, and is a significant cause of lameness in horses. Left untreated, cartilage damage and loss, pain, inflammation and dysfunction result in an ongoing cycle that eventually destroys the joint. It is the final consequence of any joint injury, whether due to infection or trauma and may result from chronic wear and tear.

Horses may develop this condition due to conformation or genetics, fractures, bone disease, or inflammatory conditions such as synovitis or capsulitis. Joints with poor conformation are more predisposed to developing chronic arthritis because of uneven loading and stress on the joint and support structures. Some low motion joints in the horse either fuse on their own eventually or can be intentionally fused. In some cases, this may be the only way to alleviate pain and restore function.