Arthritis
Degenerative joint disease (osteoarthritis)
Degenerative joint disease (DJD) is caused by the breakdown of articular cartilage, secondary to inflammation within the joint. A vicious cycle occurs in which inflammation causes the loss of proteoglycans (molecules that hold moisture in the joint lining) from the cartilage, reducing the cushioning of the joint, which then causes even more inflammation and so on. DJD may be caused by poor conformation or trauma.
Signs
There is often distention (swelling) of the joint with reduced motility of the joint and pain when it is flexed. Lameness is usually slight and intermittent having grumbled along for a while, however, will often gradually worsen over time.
Diagnosis
X-rays will often show obvious changes within the joint or in some cases of trauma, a fracture, however, in the early stages no abnormalities may be found. Retrieving a sample of the synovial fluid from the joint will show evidence of inflammation and a joint block will confirm the diagnosis.
Treatment
Treatment is aimed at reducing the inflammation and preventing/reducing cartilage damage.
Horses with acute arthritis should be rested and regular cold water hosing employed. Anti-inflammatory drugs such as phenylbutazone (‘bute’) and feed supplements containing chondroitin and glucosamine sulphate are often used to great affect.
Agents are often injected directly into the joint such as corticosteroids, to reduce inflammation, and hyaluronic acid, to help repair cartilage.
Other drugs can be injected at regular intervals into the muscle of the horse and have a similar effect as those injected into the joint.
Surgery can be performed to flush the joint to dispose of any debris and inflammatory cells that contribute to the damage.
In some cases of DJD when there are severe changes within the joint and a persistent lameness the joint can be surgically fused (arthrodesis).