Canine Hip Dysplasia (CHD) is a condition that begins in dogs as they grow and results in instability or a loose fit (laxity) of the hip joint (Figure 1). The hip joint laxity is responsible for potential clinical signs (symptoms) of hip pain and limb dysfunction and progressive joint changes. The hip joint is a ball and socket joint and continual abnormal movement of the femoral head (ball) deforms the acetabulum (socket). The long-term response to this joint laxity is the progressive loss of cartilage, the development of scar tissue around the joint, and the formation of osteophytes (bone spurs) around the ball and socket (Figure 2).
The cause of CHD is multifactorial; however, hereditary (genetics) is the biggest single risk factor. Rapid weight gain and growth through excessive nutritional intake can complicate the development of CHD. Hip dysplasia occurs most commonly in large breed dogs.
The symptoms of CHD are lameness (limping), reluctance to rise or jump, shifting of weight to the forelimbs, loss of muscle mass on the rear limbs, and hip pain. Generally, divide dogs with CHD into two groups showing symptoms of CHD:
Group 1: Younger dogs without arthritis, but with significant hip laxity
Group 2: More mature dogs that have developed hip arthritis due to CHD
Dogs may show symptoms at any stage of disease development, although many dogs with CHD do not have any obvious symptoms.