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 (OA). The terms DJD, arthritis and osteoarthritis are used interchangeably.
Canine Hip Dysplasia (CHD) was first described in 1935 by Dr. Gerry B. Schnelle. Dr. Schnelle initially called it "bilateral congenital subluxation of the coxofemoral joint". It was originally thought to be a rare condition but is now recognized as the most common orthopedic disease in dogs. This radiographic image is the first known example of CHD to be published in a scientific journal.
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 a heritable disease manifested as hip joint laxity that leads to the development of OA. So a knowledge of hip joint laxity is key to predicting the ultimate development of the OA of CHD.
Canine Hip Dysplasia afflicts millions of dogs each year and can result in debilitating orthopedic disease of the hip. Many dogs will suffer from osteoarthritis, pain, and lameness, costing owners and breeders millions of dollars in veterinary care, shortened work longevity, and reduced performance. The occurrence of CHD is well documented in large and giant breed dogs, but there is also evidence that CHD is prevalent in many small and toy breeds as well as in cats.
Hip dysplasia is a disease of complex inheritance, meaning it is caused by many genes and its expression can be affected by multiple non-genetic factors. Veterinarians and dog breeders have attempted to eliminate CHD through selective breeding strategies based on scoring of the standard hip-extended radiograph, however, the reduction of CHD frequency in pure-breed dogs has been disappointing.