Page 116 - Speedhorse April 2021

EQUINE HEALTH
DEGENERATIVE JOINT DISEASE (DJD)
Dealing With the Arthritic Horse
by Heather Smith Thomas
Older horses and hard-working ath- letic horses often develop arthritis (joint inflammation) in various joints
after hard use or repetitive wear and tear. Degenerative joint disease (DJD) is just another name for osteoarthritis, which is the most com- mon type of arthritis in horses. This is a chronic disease in which the cartilage on the ends of bones wears down from the constant use and movement of a joint, resulting in loss of joint mobility, along with swelling, heat and pain.
Excessive stress on a joint (resulting in damage and DJD) is sometimes due to uneven weight- bearing, due to poor conformation, hoof imbal- ance or other health problems. Osteochondrosis dissecans (OCD) in young horses can cause malformation of cartilage, leaving “holes” or weak spots that later lead to joint problems after the horse grows up and goes to work.
Broodmares and stallions retired from racing often have joint issues, and older horses that are still racing may have soreness that needs to be managed. Painful, stiff joints can often be man- aged to keep most of these horses comfortable enough to continue performing. The farrier can usually help with proper shoeing, but some cases may need to be managed medically.
Most training strategies for racehorses and other equine athletes try to prevent joint injury and minimize wear and tear, or try to maintain joint health in horses that are already affected by some form of joint disease. Lack of perfor- mance (such as not running at peak ability) as a result of joint disease is often the first clue that there is a problem, before the horse shows
actual lameness and/or radiographic changes. In a normal, healthy joint, the bones
that comprise the joint can move freely. The articulating surfaces (subchondral bone) are covered with a cartilage layer (overlying the subchondral bone) and encased in fibrous joint capsule that contains lubricating fluid. The joint capsule is lined with synovial membrane that creates the lubricating synovial fluid. This combination of smooth cartilage surfaces and thick synovial, slippery fluid eliminates friction and allows the bone surfaces within the joint
to move freely and independently of each other without damage or pain. If anything disrupts the joint capsule and its ability to create lubri- cating fluid, or damages the joint cartilage, the result is inflammation and arthritis.
Normal synovial fluid contains large molecules called hyaluronan—the ingredient that gives this fluid its thick and slippery characteristics that
help minimize friction between the moving parts. Lack of hyaluronan within synovial fluid increases friction and puts the cartilage at risk for excessive wear—and eventually bone grating on bone.
114 SPEEDHORSE April 2021
Broodmares and stallions retired from racing often have joint issues that need to be managed.