Canine Hip Dysplasia

There are numerous misconceptions and misunderstandings surrounding the problem known as Canine hip dysplasia. The condition known as Hip dysplasia is a fairly common degenerative disease found in the animal's joints. We have plentiful data about hip dysplasia in dogs, and there are also a number things we suspect about this common cause of limping, but even with the amount of data amassed, there are still some things that we simply do not understand about disease.

What is Canine hip dysplasia?

To have an understanding as to what hip dysplasia really is, we need to start with a look at the joint that is being affected. The hip joint forms the attachment of the hind leg to the body and is known as a ball and socket joint. The ball portion is the head of the femur while the socket (acetabulum) is situated on the pelvis. In a properly formed joint the ball rotates freely within the socket. To facilitate clean and free rotation the bones are shaped to match each other perfectly, with the socket surrounding the ball. To give the joint strength, the two bones are held together by a ligament. The ligament attaches the femoral head directly to the acetabulum (the socket). Also, the joint capsule, which is a very strong band of connective tissue, encircles the two bones adding further stability. There is an area where the bones actually make contact with each other and is known as the articular surface. If properly developed, this area is perfectly smooth and is also cushioned with a layer of a spongy material called cartilage. In a normally developed dog, all of these individual components work in unison assisting in smooth and stable joint function.

Hip dysplasia joint" ALIGN=LEFT WIDTH=150 HEIGHT=178 BORDER=1>The condition known as “Hip dysplasia” is the result of abnormal development of the hip joint when the dog is young. It can affect both right and left sides, which is known as Bilateral Hip Dysplasia, although it can appear in only one joint. It is brought about by the looseness or “laxity” of the musculature, connective tissue, and ligaments that normally support the joint. Most dysplastic dogs are born with normal hips but due to genetic and possibly other factors, the soft tissues that surround the joint start to develop abnormally as the puppy grows. The most important part of these changes is that the bones are not held in place but actually move apart. The joint capsule and the ligament between the two bones stretch, adding further instability to the joint. As this happens, the articular surfaces of the two bones lose contact with each other. This separation of the two bones within a joint is called subluxation and this, and this alone, causes all of the resulting problems we associate with the disease.

What are the symptoms of hip dysplasia?

Dogs of all ages are subject to the symptoms of hip dysplasia and the resultant osteoarthritis. In severe cases, puppies as young as five months will begin to show pain and discomfort during and after vigorous exercise. The condition will worsen until even normal daily activities are painful. Without intervention, these dogs may be unable to walk at all by a couple years of age. In most cases, however, the symptoms do not begin to show until the middle or later years in the dog's life.

The symptoms are typical for those seen with other causes of osteoarthritis. Dogs may walk or run with an altered gait, often resisting movements that require full extension or flexion of the rear legs. Many times, they run with a 'bunny hopping' gait. They will show stiffness and pain in the rear legs after exercise or first thing in the morning. Most dogs will warm up out of the muscle stiffness with movement and exercise. Some dogs will limp and many will decrease their level of activity. As the condition progresses, the dogs will lose muscle tone and may even need assistance in getting up. Many owners attribute the changes to normal aging but after treatment is initiated, they are shocked to see much more normal and pain-free movement return.

Who gets hip dysplasia?

Hip dysplasia can be found in dogs, cats, and humans, but for this article we are concentrating only on dogs. In dogs, it is primarily a disease of large and giant breeds. The disease can occur in medium-sized breeds and rarely even in small breeds. It is primarily a disease of purebreds although it can happen in mixed breeds, particularly if it is a cross of two dogs that are prone to developing the disease. German Shepherds, Labrador Retrievers, Rottweilers, Great Danes, Golden Retrievers, and Saint Bernards appear to have a higher incidence, however, these are all very popular breeds and may be over represented because of their popularity. On the other hand, Greyhounds and Borzois have a very low incidence of the disease.