The hip joint is composed of the ball and the socket. The development of hip dysplasiais 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 asmalformation), 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 Boxer, 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
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
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.
Your dog may be treated for hip dysplasia on an outpatient basis as long as it does not require surgery. The decision for whether your dog will undergo surgery will depend on your dog's size, age, and intended function (i.e., whether your dog is a working dog, as many large breeds tend to be). It will also depend on the severity of joint looseness, degree of osteoarthritis, your veterinarian's preference for treatment, and your own financial considerations. Physiotherapy (passive joint motion) can decrease joint stiffness and help maintain muscle integrity. Swimming is an excellent form of physical therapy, encouraging joint and muscle activity without increasing the severity of joint injury.
Weight control is an important aspect of recovery and is recommended to decrease the pressure applied to the painful joint as the dog moves. You and your veterinarian will need to work together to minimize any weight gain associated with reduced exercise during recovery. Special diets designed for rapidly growing large-breed dogs may decrease the severity of hip dysplasia.
The TPO surgery rotates the socket for dogs less than a year old. The juvenile pubic symphysiodesis surgery is performed on dogs that are younger than six months, fusing part of the pelvis together to improve hip joint stability. A total hip replacement is done in mature dogs that are not responding well to medical therapy and that are suffering from severe osteoarthritis. Most dogs will handle this type of surgery, with acceptable hip function after the recovery period. Excision arthroplasty is performed when hip replacement surgery is cost-prohibitive. In this surgery the ball of the hip joint is removed, leaving muscles to act as the joint. This surgery works best for dogs weighing less than 44 pounds, and for dogs with good hip musculature.
Your veterinarian may also prescribe anti-inflammatory drugs to reduce swelling and inflammation, along with pain medications for lessening the severity of the pain.
Living and Management
Your veterinarian will schedule follow-up appointments with you to monitor any changes in your dog's hip dysplasia. X-rays will be taken for comparison with previous x-rays. If your dog has undergone surgery, these x-rays will indicate the rate of post-surgical healing. If your dog is being treated as an outpatient only, the x-rays may indicate the rate of deterioration in the hip joint.
If your dog has been effectively diagnosed with hip dysplasia, it should not be bred out, and the dam and sire (the parents) of your pet should not be bred again, since this condition is often acquired genetically. Special diets designed for rapidly-growing large-breed dogs may decrease severity of hip dysplasia.