Defining Canine Hip Dysplasia
Dysplasia comes from the Greek words dys, meaning "disordered" or "abnormal", and plassein meaning "to form". The expression hip dysplasia can be interpreted as the abnormal or faulty development of the hip. Abnormal development of the hip causes excessive wear of the joint cartilage during weight bearing, eventually leading to the development of arthritis, often called degenerative joint disease (DJD) or osteoarthritis. The terms DJD, arthritis and osteoarthritis are used interchangeably.
CHD was first described in 1937 by Dr. Gerry B. Schnelle. In a paper entitled Bilateral Congenital Subluxation of the Coxofemoral Joints of a Dog Schnelle writes: "The condition described herein, rare though it may be, should be recognized as being congenital and potentially hereditary, and the dog or bitch in which it occurs should be destroyed or sterilized in the eugenic interests of the breed."
In 1966, Henricson, Norberg and Olsson refined the definition of CHD describing it as: "A varying degree of laxity of the hip joint permitting subluxation during early life, giving rise to varying degrees of shallow acetabulum and flattening of the femoral head, finally inevitably leading to osteoarthritis."
Today, the general veterinary consensus is that hip dysplasia is hip joint laxity resulting in DJD. Environmental factors may also play a role in the development of osteoarthritis.