Hip Dysplasia

Hip dysplasia is a progressive degenerative condition of the pelvic joint that can lead to severe lameness and pain in large breed dogs. It can be very debilitating, but with the help of several ingenious surgical techniques, the function of the leg can be restored, sometimes almost to normal capacity. Hip dysplasia occurs when the head of the femur (the upper bone in the hind leg) does not fit into the socket (acetabulum) of the joint properly. Patients that develop this condition are often first seen for the problem when they are fairly young.

Dr. Dianne Dunning, a veterinary orthopedic surgeon at the University of Illinois Veterinary Teaching Hospital in Urbana, says, "Severe pain can result in a young dog when the head of the femur pulls away from the joint and rides on the rim of the acetabulum during movement (called subluxation). It can put stress on the joint and tear the joint capsule. The pain often goes away on its own as the joint stabilizes, but problems with the conformation or shape of the joint can remain, causing problems later in life."

The changes seen in older animals with hip dysplasia are caused by osteoarthritis (also called degenerative joint disease) and are the result of degeneration of cartilage accompanied by bone formation and fibrosis around the joint. Both the acetabulum and the head of the femur to change in shape until they no longer form a stable joint, causing lameness and pain.

If the problem is noticed early enough (when the head of the femur and the acetabulum are still mostly intact), then hip dysplasia can sometimes be corrected by a procedure called a triple pelvic osteotomy, in which the pelvis is actually cut into three pieces and repositioned so that the head of the femur fits more snugly into the acetabulum. This procedure is usually best for animals that are young and have not developed too many degenerative changes in the joint. It requires that the animal have 6 to 8 weeks of rest after surgery to ensure that the bones of the pelvis heal correctly.

For dogs with extensive degeneration of the joint, there is a treatment called a femoral head and neck osteotomy, which involves the surgical removal of the head and neck of the femur. Dr. Dunning says, "Many pets can do very well without the pelvic joint because the muscles of the hind leg can compensate to form a 'muscular joint' just like the one found naturally in the forelimb of domestic animals. Chances are that animals receiving this treatment will never be great athletes, but they can be perfectly functional family pets."

Getting the dog up and moving around is the best post-operative care for this kind of surgery. Physical therapy is key to rehabilitating the leg. There are no fractures that require healing, and the sooner the dog begins to develop strength in the muscles of the hind leg, the better.

For those people who want their dog to return to pain-free, mechanically sound, normal hip function, there is a more complex treatment option available called total hip replacement. Dr. Dunning says, "This treatment is allows animals to be more comfortable and return to an active life-style and in some cases perform at an optimal athletic capacity."

Your dog may be a candidate for a total hip replacement if he or she has hip dysplasia, is fully mature and in good health, and weighs more than 30 pounds. A thorough preoperative examination is required to rule out other orthopedic and general health concerns prior to surgery.

In this procedure the head and medullary cavity of the femur is removed and an implant made of cobalt chrome stainless steel is put in its place. The acetabulum is replaced by a high-polymer plastic cup. Together they form a new joint that can function almost as well as a natural joint. Post-operative care is fairly extensive, requiring at least 6 to 8 weeks of cage rest. However, most dogs walk on their new hip immediately after surgery.

Post-surgical Infections

Post-surgical infection is a major concern with this procedure. Dr. Dunning says, "We screen potential candidates for this surgery thoroughly to make sure that they are in good condition because any pre-existing infection could jeopardize the success of the implant." In addition, precautions must be taken to ensure that infection does not spread to the new joint after the procedure. This means that prophylactic antibiotics should be administered to the dog when other surgical or dental procedures are done, and its overall health should be monitored closely.

If you think that your dog could be suffering from hip dysplasia, or you would like more information about any of these procedures, contact your local veterinarian or call the Small Animal Clinic at the University of Illinois at (217/333-5300).

The above part of the article has been reprinted from College of Veterinary Medicine, University of Illinois  website
Author: Jennifer Stone,Information Specialist

Role Of Environmental Factors

According to recent studies conducted by Randi I. Krontveit, Norway, hip dysplasia in dogs is affected to a larger degree than previously thought by the environment in which puppies grow up. The previous thinking was that rapid growth and a high body weight are factors that increase the risk of developing HD. On the contrary, the research found that dogs with the slowest growth rate (the Newfoundland) had the highest incidence of HD. The Irish Wolfhound had the lowest incidence of HD (10%), although had the fastest rate of growth. The opportunity to exercise daily in parks up until the age of three months reduced the risk of HD, whereas the daily use of steps during the same period increased the risk.