Hip dysplasia is a deformity of the hip joint that occurs during growth. It is a leading cause for hind limb discomfort and can be easily diagnosed by a physical exam and an x-ray taken under anesthesia. The hip joint is a "ball and socket" joint. During growth, both the "ball" (the head of the femur or thighbone) and the "socket" in the pelvis (acetabulum) must grow at equal rates. In hip dysplasia, this uniform growth during puppyhood does not occur. The result is laxity of the joint, followed by degenerative joint disease (DJD) or osteoarthritis (OA), which is the body's attempt to stabilize the loose hip joint.
Although any dog can be affected, it is predominantly seen in larger dogs such as German Shepherds, Saint Bernards, Labrador Retrievers, Golden Retrievers, Old English Sheepdogs, Bulldogs, etc. Large mixed-breed dogs are also at risk for developing hip dysplasia and should be fed a special large breed growth diet the first year.
The degree of lameness that occurs is dependent on the extent of these arthritic changes. Some pets with significant signs of hip dysplasia or osteoarthritis 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, genetics and diet. The genes involved in hip dysplasia have not been conclusively identified, but it is believed to involve more than one gene. Advances in nutritional research have shown that diet also plays an important role in the development of hip dysplasia. Large breed (generally greater than 50 lbs.) puppies should be kept at a normal, lean weight during growth, rather than overfed and encouraged to grow “big.”
One study of puppies at-risk for hip dysplasia found that when fed as much as they wanted to eat, two-thirds of the puppies went on to develop hip dysplasia, while only one-third of puppies fed measured meals suffered from hip dysplasia. A study of German shepherds found that overweight puppies were almost twice as likely to develop hip dysplasia as their normal-weight counterparts. These studies have allowed food manufacturers to develop specially formulated diets for large breed puppies.
Weakness and pain in the hind legs are the usual clinical signs. The dog appears wobbly and is reluctant to rise from a sitting or lying position. Some dogs will limp or be reluctant to climb stairs. These signs can be seen in puppies as early as a few months old but are most common in dogs one to two years of age. Dogs with mild hip dysplasia on X-rays may develop minimal arthritis without clinical signs until they are older. In fact, although hip dysplasia begins in puppyhood, most dogs don’t develop clinical signs until they are older. It often takes years of gradual bone degeneration until a dog becomes symptomatic.
A hip radiograph under general anesthetic 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. A common brand is Rimadyl and comes in a generic form (Carprofen). The choice of medication is made on an individual basis, and various drugs may be tried before finding the most effective one. Most dogs with hip dysplasia should receive omega-3 fatty acid nutritional supplements. Many dogs with painful hip dysplasia will benefit from a supplement called Adequan, which are (polysulfated-glycosaminoglycan) injections given on a regular basis. Recently, CBD extracts have proven to be effective. Moderate daily exercise, avoiding high impact activities such as jumping, may help keep the patient mobile and strengthen surrounding support structures. Physical therapy has been demonstrated to be highly effective at improving an affected dog’s quality of life and should be part of any treatment regimen. Since excess weight puts undue stress on the hip joints, weight loss is strongly recommended in overweight dogs.
The alternative to NSAID and medical therapy is surgery. There are several surgical procedures available to treat hip dysplasia. The two most common 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 age, condition, and lifestyle.
Acupuncture, class 4 lasers, stem cell treatments, and traditional Chinese medicine have all been used to treat hip dysplasia with varying results. To date, rigorous scientific studies on these alternative therapies have been sparse. Your veterinarian will share with you his experience with therapeutic choices.
Dr. Lamb is the Veterinarian at the Manchester Animal Hospital.
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