Hip Dysplasia in Dogs

Canine Hip Dysplasia is a condition which begins in immature dogs with instability or a loose fit of the hip joint. The hip joint laxity is responsible for early clinical signs and joint changes. The abnormal motion of the hip stretches the fibrous joint capsule and ligament connecting the head of the femur to the pelvis, producing pain and lameness. The acetabulum (the hip socket) is easily deformed by continual movement of the femoral head. Micro fractures of the acetabular bone may occur, causing further pain and lameness in the immature dog. The dog’s physiologic response to joint laxity is proliferative fibroplasia or thickening of the joint capsule and formation of osteophytes or new bone on the rim of the acetabulum and the femoral neck.

Hip dysplasia present in young animals as instability of the hip joint. As the dog bears weight, the head of the femur (the “ball”) comes out of the acetabulum (the “socket”) as far as the joint capsule and ligament will allow. The joint capsule and ligament gradually get stretched allowing the femoral head to come out of the acetabulum even further.

The result of the instability in the joint is abnormal wear of the cartilage. Cartilage wear leads to the formation of osteophytes (bone spurs) and joint capsule thickening, which are the characteristic signs of osteoarthritis or degenerative joint disease. These responses help to stabilize the hip joint. The new bone formation is visible on radiographs and considered to be osteoarthritis or degenerative joint disease.

The osteoarthritis progresses over the life of the dog. However, radiographic signs of osteoarthritis do not always correlate with clinical function.

Causes of hip dysplasia

Causes of hip dysplasia are considered to be multifactorial; including both hereditary and environmental factors. Rapid weight gain and growth through excessive nutritional intake may encourage the development of hip dysplasia. Mild repeated trauma causing synovial (joint lining) inflammation may also be important.

Incidence and Prevalence of hip dysplasia

The incidence of hip dysplasia is greatest in large breed dogs. Two populations of animals show clinical signs of lameness: (1) patients 5 to 10 months of age, and (2) patients with chronic degenerative joint disease.

Signs and Symptoms

The clinical signs of hip dysplasia are lameness, reluctance to rise or jump, shifting the weight to the forelimbs, loss of muscle mass on the rear limbs, and pain when the hips are manipulated. Dogs may show clinical signs at any stage of development of the disease, although many dogs with hip dysplasia do not show overt clinical signs. Some dogs are painful at 6 to 8 months of age but recover as they mature. As the osteoarthritis progresses with age, some dogs may show clinical signs similar to people with arthritis such as lameness after unaccustomed exercise, lameness after prolonged confinement, and worse problems if they are overweight.

Learn more about hip dysplasia from Board Certified surgical specialists:

NB: Hip dysplasia is a great example of how the body can compensate for structural changes. There is little correlation with clinical signs and x-ray findings. As always, I therefore find it most effective to treat the individual patient. Not the diagnostic test results.–Dr. Jeff

Please note: The information provided here is intended to supplement the recommendations of your veterinarian. Do not disregard veterinary advice or delay treatment based on information on this site. Nothing can replace a complete history and physical examination performed by your veterinarian. -Dr. Jeff