Sep. 5, 2000 Every year thousands of dogs are hobbled by a painful condition called hip dysplasia, a degenerative disease of the hip in which the ball and socket joints no longer fit tightly. This disabling ailment usually strikes large breeds, like Labrador retrievers, German shepherds and Saint Bernards.
Dr. Kyle Mathews, assistant professor of small animal surgery at North Carolina State University's College of Veterinary Medicine, is among a team of veterinarians who have developed a new method of preventing hip dysplasia. The procedure they're developing, called Juvenile Pubic Symphysidesis (JPS), is less invasive than other treatments and shows great promise as a permanent preventive measure.
JPS involves heating an area near the center of the pelvis to kill cells responsible for pelvic development. By altering these "growth plates," veterinarians can force the bones of the pelvis to grow at different rates. That makes the pelvis grow at an angle that provides a better fit for the hip. When mature, the hip socket has rotated to a more horizontal angle, thus making it less likely the ball on the end of the femur will pop out. The socket of a loose-fitting hip will eventually wear down to look like a saucer, causing great pain for the animal.
Mathews is working on JPS in collaboration with Dr. R. Tass Dueland at the University of Wisconsin.
The procedure must be performed when dogs are between 16-20 weeks of age, with maximum benefit gained when the dog is 16 weeks old. After that, the benefits decrease with each successive week until the puppy is 20 weeks old. At that point the pelvis is probably too developed for a JPS to have any effect on growth.
The best time to perform a JPS, Mathews says, is when the dog is being spayed or neutered. The animal only needs to be anesthesized once, and both surgical procedures are in the same area of the body. The incision for the JPS is about 3-4 inches long. So far there appear to be no side effects to the new procedure.
Clinical trials of JPS appear to be successful. Dogs that have undergone the procedure have had significant improvement in hip alignment, Mathews says. "After two years their hips are tight. They don't seem to have signs of hip dysplasia, even though they were at risk of developing it," he says. He's even performed the procedure on his own Labrador retriever which appeared to be at risk of hip dysplasia.
Early detection of hip dysplasis is key, he adds. "Most young dogs don't show signs of clinical hip dysplasia, or the owners don't notice until the dog is a year of age, and then it's too late to do this procedure. The hope is that veterinarians and breeders will learn that this procedure is an option, and screen their dogs."
There are at least two other corrective surgical procedures for hip dysplasia now used. One, called a Triple Pelvic Osteotomy, was adapted from a technique used on humans. It involves cutting the bone surrounding the hip socket from the joint, rotating the joint for a better fit, then plating the bones back together. This technique also is used in young animals, but requires extensive surgery.
The second option is total hip replacement, a permanent and costly alternative for older animals that have already developed arthritis secondary to hip dysplasia. This procedure costs up to $2,500 per joint.
"I got to thinking maybe there's something we can do to affect the growth of the pelvis that would give us the same result, without major orthopedic surgery," Mathews says. "The ideal procedure would be something that is minimally invasive and would take care of the problem before dogs developed arthritis -- essentially, it would keep them from developing the arthritis. So it had to be something you could do in a young animal."
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