If your dog has been diagnosed with canine hip dysplasia (CHD), you are probably wondering, “How did this happen?” Spoiler alert: It’s way more complicated than you might think. Scientists don’t fully understand what causes hip dysplasia in dogs.

What causes hip dysplasia in dogs? It’s the million dollar question.

Literally…

Embrace Pet Insurance, one of the leaders in the 774 million dollar pet insurance industry, has had over 1.4 million dollars in claims for hip dysplasia.

Explaining where and how canine hip dysplasia (CHD) begins is not simple. Hip dysplasia is a condition in which the ball and socket joint, created by the femur and pelvis, doesn’t function properly.

This problem begins at birth, and there are a slew of factors involved. It’s not black and white. But we do know that genetics is the most important factor. This is why conscientious breeders are so concerned about keeping their gene pool free from hip dysplasia. Many of these genetic puzzle pieces are poorly understood, so research projects are underway to learn more.

Stages of Hip Dysplasia in Dogs

In dogs with CHD, puppies are born with normally appearing hips and then develop hip changes as they grow. The head of the femur (the “ball” in the socket) may not properly develop. Instead of turning from cartilage to bone, which is the normal growth process, the head may stay soft and partially cartilaginous.

Further, these dogs often have reduced amounts of hyaluronic acid and an abnormal ratio of collagen-type fibers—all critical parts of joint health. These factors lead to joint “looseness” (called laxity).

Because the joint becomes “loose,” the femoral head (the ball) is not kept in the correct position in the hip socket. It is actually partially dislocated. With each step the dog takes, the joint wears abnormally. This leads to a shallow socket and a flattened femoral head.

The body tries to correct this by increasing fluid in the joint, which in turn causes swelling and more changes to the joint. It is a vicious cycle, causing more and more damage.

Arthritis is the end-stage of CHD. In arthritis, the changes to the joint are permanent and cause ongoing pain and discomfort for the dog. Medical treatment is aimed at reducing the inflammation and pain from the arthritis.

What breeds are affected and why?

Hip dysplasia can occur in any breed of dog (and even cats) but occurs most frequently in large, heavy breeds like German shepherds, Mastiffs, Golden retrievers, Newfoundlands, Rottweilers, and Labrador retrievers. A genetic component has been identified in many of these breeds.

There are documented studies linking the development of hip dysplasia to nutrition and body mass. CHD can be worsened by rapid weight gain and excess nutritional supplementation (as can occur when growing dogs are given supplements they do not need or an inappropriate diet). (To learn how to determine your dog’s optimum weight, check out my article: Canine Body Condition Score: Find Your Dog’s Number.)  It is also important that large and giant breed dogs are fed puppy food that does not have excess calcium or phosphorus.

Environmental factors are also known to impact the development of CHD. Puppies should be protected from injuring themselves on slippery floors. Exercise should be in moderation and never be forced. A study in 2012 even went so far as to conclude that puppies under three months of age should not be allowed to climb stairs.

The bottom line is that layered on top of the genetic foundation, multiple factors influence a dog’s propensity to develop CHD. In addition to physical activity and nutrition, these include muscle mass, environment, and hormones. For in-depth information about hip screening procedures and treatment options, I recommend these two resources: The Orthopedic Foundation for Animals (OFA) and AIS PennHip.

Did you know that elbow dysplasia is another common diagnosis in large breed dogs? To learn more, please read my article Canine Elbow Dysplasia: How ToeGrips Helped a Great Pyrenees.

Do you have questions about what causes hip dysplasia in dogs? Please comment below.