Osteoarthritis

(degenerative joint disease, arthritis)

Osteoarthritis (OA) is a slow and progressive joint disease characterized by loss of joint cartilage and subsequent exposure of underlying subchondral bone. The condition is a self-perpetuating disorder characterized by joint pain, stiffness and chronic inflammation (heat and swelling). There is gradual loss of joint cartilage, a narrowing of the joint space, deterioration of the joint synovial fluid, and sclerosis (hardening) of subchondral bone, and eventually production of joint osteophytes (bone spurs).

OA is often referred to as primary or secondary. This simply refers to wether it has developed by itself naturally (wear and tear, age, breed) or as a result of another factor (trauma, obesity, developmental orthopaedic diseases, etc).

Osteoarthritis is a common complaint, especially in overweight dogs, and negatively affects the individual dog’s quality of life, as pain limits movement. 77% of overweight Labradors develop OA in either 2 or 3 joints by 8 years of age.

Theories about the onset of OA vary somewhat in literature, and there might be more than one causative factor. OA has been reported following trauma, either through direct joint injury or resultant alteration in biomechanics, and excessive loading of joints (obesity). Adipose tissue (body fat) also releases inflammatory cytokines, and elevated levels of inflammatory mediators are found within obese subjects, and therefore obesity is thought to contribute to the onset of OA on a pathological level also, not just biomechanical. Obesity increases the oxidative stress on the body which is also associated with the onset of OA, and is therefore probably the most important risk factor for OA, as it incorporates inflammatory, biomechanical and oxidative risk factors.