Hypothesis #2: Congenital Deformities Since the facts have led us to isolate this problem to the hip/pelvic area, we focused our congenital deformity discussion on hip dysplasia. Hip dysplasia is an abnormal development of the hip joint usually bilaterally. Dysplastic dogs are actually born with normal hip joints and subsequently undergo progressive structural changes. These include joint laxity ( caused by failure of muscles to develop and reach functional maturity concurrently with the skeleton), swelling, fraying, and rupture of the teres ligament, shallow articular cavities, subluxation of the femoral head, erosion of the articular cartilage, eburnation of subchondral bone ( harding into ivory like mass), remodelling of the acetabular rim, and femoral head, and periarticular osteophyte formation. Osteophyte formation and articular erosion usually lead to the pain as seen in this case. What starts the process is still under debate, however there are many contributing factors. There is a genetic predisposition to congenital dislocation of the hip as well as environmental factors ( i.e. diet) that are superimposed on the genetic susceptibility of the individual