Hip Dysplasia is a birth defect of the hip joint found most often in large breed dogs. Hip dysplasia is a deformity of the hip, which occurs during growth. The hip joint is a “ball and socket” joint. During growth both the ball (the head of the femur or thighbone) and the acetabulum (the socket in the pelvis) must grow at equal rates. In hip dysplasia this uniform growth does not occur. The result is laxity of the joint followed by degenerative joint disease or arthritis, which is the body’s attempt to stabilize the loose hip joint. The degree of lameness that occurs is dependent on the extent of these arthritic changes and may not be correlated with the appearance of the hip joint on x-rays. Some pets with significant signs of hip dysplasia on x-rays may not exhibit any clinical signs while others with minimal changes may experience severe pain and lameness.
There are two primary causes of hip dysplasia: genetic and diet. The genes involved have not been conclusively identified, but it is believed to involve more than one gene. New advances in nutritional research reveal that diet plays an important role in the development of hip dysplasia. Large breed puppies should be fed a special diet during the first year of life to reduce this risk. Although any dog can be affected, it is predominantly seen in larger dogs such as German Shepherds, St Bernard’s, Labradors, Labrador Retrievers, Old English Sheepdogs and Bulldogs. Mixed-breed large dogs are also at risk for developing hip dysplasia and should also be fed a special large breed growth diet the first year.
Symptoms include weakness and pain in the hind legs, the dog appears wobbly and is reluctant to rise from a sitting or lying position (this can be seen in puppies a few months old but is most common in dogs one to two years of age). Dogs with mild hip dysplasia on x-ray may develop minimal arthritis without clinical signs until they are older. A hip radiograph is the preferred method for diagnosing hip dysplasia. Clinical signs and palpable joint laxity may also indicate hip dysplasia. Any pet suspected of having hip dysplasia should be radiographed as soon as possible.
Treatment depends upon the pet’s clinical signs and amount of discomfort. There are very effective non-steroidal anti-inflammatory drugs (NSAIDs) that have minimal side effects. The choice of medication is made on an individual basis and various drugs may be tried before finding the most effective one. The alternative to NSAID therapy is surgery. There are several surgical procedures available to treat hip dysplasia. The two most surgical techniques for hip dysplasia are total hip replacement and femoral head ostectomy (FHO). The choice of surgery will be determined by your pet’s condition and lifestyle.