Most joints appear normal at birth which makes early detection difficult. As the dog grows the acetabulum (sockets) become more shallow and the hip starts to subluxate (partially dislocate) stretching or rupturing the main ligament (round ligament) holding the femoral head (ball) in the joint. This leads to excessive wear on the joint and loss of articular cartilage (smooth lining of the joint) i.e.. arthritis.

Clinical signs can vary significantly both in severity and age of onset. Early signs may be changes in gait (pattern of walking) or lameness in the hind legs after exercise. As the condition progresses the lameness becomes more pronounced generally being worst when first rising as is typical of arthritis.

Radiographs (Xray) are used to diagnose HD and to screen dogs before breeding. Advanced HD shows as flattening of the femoral head and excess bone around the joint. Early assessment involves measuring the amount of the femoral head within the acetabulum when the hind legs are held in full extension behind the dog. These Xrays are usually taken at 12 to 18 months of age.

Treatment in the early stages may only require rest and analgesics (pain relief drugs). More prolonged pain relief may be achieved with pectinomyotomy surgery (cutting the pectineal muscle which runs from the pelvis to the inside of the thigh). In young dogs with dysplasia but limited arthritic changes a triple pelvic osteotomy can be a very effective treatment. In this operation the pelvis is cut in three places to release the acetabulum which is then rotated and plated in place to decrease the shallowness of the joint. Where the degree of arthritis is advanced either arthroplasty (removal of the femoral head) or total hip replacement can be considered as surgical options. Total hip replacement requires advanced surgical skill and is relatively expensive.

The use of radiographic assessment of dogs prior to use for breeding has greatly contributed to the reduction of HD in a number of breeds.