Degenerative joint disease is actually several progressive disorders that result in a deterioration of some of the anatomical structures within the coffin joint.

There is a deterioration of the articular cartilage, changes within the bony structures and changes within the soft tissues involved with the joint. When the articular cartilage deteriorates, it splits into fragments similar to the effects that a jackhammer has on a smooth concrete surface.

Changes occur within the bone that result in microfractures and areas of deterioration called cysts. The joint capsule, synovial membranes and a number of associated tendons and ligaments become inflamed. When the synovial membranes are inflamed, this condition is termed synovitis. The fluid within the joint has abnormal characteristics and is excessive. The term osteoarthritis is synonymous with degenerative joint disease (DJD).

Types Of Degenerative Joint Disease

DJD in the horse can be divided into four categories:

1. Acute: This category involves high motion joints such as the carpal and metacarpophalangeal joints. This type of DJD usually affects 2- and 3-year-old horses that are involved in a racing career or heavy workload.
2. Insidious: This type of DJD involves the high load, low motion joints such as the interphalangeal and intertarsal joints. This usually occurs in older or aged horses, but should not be overlooked in younger competitive horses such as those involved in eventing. This is the type of DJD that is most commonly found within the coffin joint.
3. Incidental Articular Cartilage Erosion: This DJD is comparable to that found within the joints…