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Canine Hip Dysplasia in Dogs

The hip joint is composed of the ball and the socket. The development of hip dysplasia is determined by an interaction of genetic and environmental factors, though there is a complicated pattern of inheritance for this disorder, with multiple genes involved. Hip dysplasia is the failure of the hip joints to develop normally (known as malformation), gradually deteriorating and leading to loss of function of the hip joints.

Hip dysplasia is one of the most common skeletal diseases seen in dogs. Gender does not seem to be a factor, but some breeds are more likely to have the genetic predisposition for hip dysplasia than other breeds. Large and giant breeds are most commonly affected, including the Great Dane, Saint Bernard, Labrador Retriever, and German Shepherd. Rarely, small breed dogs can also be affected, but are less likely to show clinical signs.

Hip dysplasia often begins while a dog is still young and physically immature. Early onset usually develops after four months of age. There are also cases of later onset, where hip dysplasia develops later due to osteoarthritis, a form of joint inflammation (arthritis) that is characterized by chronic deterioration, or degeneration of the joint cartilage.

Symptoms and Types

Symptoms depend on the degree of joint looseness or laxity, the degree of joint inflammation, and the duration of the disease.

• Early disease: signs are related to joint looseness or laxity
• Later disease: signs are related to joint degeneration and osteoarthritis
• Decreased activity
• Difficulty rising
• Reluctance to run, jump, or climb stairs
• Intermittent or persistent hind-limb lameness, often worse after exercise
• “Bunny-hopping,” or swaying gait
• Narrow stance in the hind limbs (back legs unnaturally close together)
• Pain in hip joints
• Joint looseness or laxity – characteristic of early disease; may not be seen in long-term hip dysplasia due to arthritic changes in the hip joint
• Grating detected with joint movement
• Decreased range of motion in the hip joints
• Loss of muscle mass in thigh muscles
• Enlargement of shoulder muscles due to more weight being exerted on front legs as dog tries to avoid weight on its hips, leading to extra work for the shoulder muscles and subsequent enlargement of these muscles

Causes

Influences on the development and progression of hip dysplasia are concurrent with both genetic and environmental factors:

• Genetic susceptibility for hip looseness or laxity
• Rapid weight gain and obesity
• Nutritional factors
• Pelvic-muscle mass

Diagnosis

Your veterinarian will perform a complete physical exam on your dog, including a blood chemical profile, a complete blood count, an electrolyte panel and a urinalysis. Inflammation due to joint disease may be noted in the complete blood count. As part of surveying the physical symptoms and fluid work-ups, your veterinarian will also need a thorough history of your dog's health, onset of symptoms, and any possible incidents or injuries that may have contributed to your dog's symptoms. Any information you have on your dog's parentage will be helpful as well, as there may be a genetic link.

X-rays are crucial for visualizing the signs of hip dysplasia. Some of the possible findings may be degenerative disease of the spinal cord, lumbar vertebral instability, bilateral stifle disease and other bone diseases.