Canine Hip Dysplasia

The word dysplasia means simply "improper growth". Since the hip is composed not only of bone but also the muscles, tendons, ligaments and joint capsule holding the bones together, there are limitless ways in which "improper growth" can occur. Therefore, hip dysplasia is not an "all-or-nothing disease", but a syndrome that may progress from clinically undetectable to marked hindlimb debility. (All dogs have normal hips at birth). If, due to hereditary predisposition or enviromental influence,^* the bones and soft tissues mature out of synchrony, there develops an incompatibility of the parts of the hip.

This leads to joint instability so that the ball and socket are not heldtogether properly. When joint instability is present, the weight of the animal is no longer borne only by the perfectly smooth cartilage surfaces of the joint. lesions (therefore, pain) develop at these sites of abnormal pressure. This is the start of degenerative joint disease or arthritis, which is what actually producesthe signs we recognize (e.g., wobbly gait, soreness, slow rising, nonweight bearing). Excessive height, weight, or rate of growth and small pelvic muscle mass are the most critical anatomical features influencing the occurrence of hip dysplasia. It is obvious then how important a controlled diet and exercise programs are for growing dogs.

There are two major groups of dogs that are presented to a veterinatian for dysplastic changes:

1. Dogs five to eight months old, where genetic and environmental influences have combined to overpower the normal remodeling capacity of the hip.
2. Dogs one to ten years old, where development of degenerative joint disease is milder and slower.

The young dogs often have difficulty rising (especially in the morning), and may show gait problems when walking, running or using stairs. Their pain comes from many sources; tiny fractures where the loose femur hits the rim of the acetabulum, torn muscles, and torn joint capsule. Treatment usually consists of the following:

1. Limited exercise: let the dog pace itself.
2. Limited , but adequate nutrition - too many calories will enhance abnormal hip growth. (ask yourvet for diet plan for you dog.)
3. Analgesics (e.g., buffered aspirin) ONLY AS NEEDED so as to minimize but not mask the discomfort.(Again ask your vet about amount that should be given).

With strict adherence to these control methods, the hip joint may fully mature, the fractures can heal and the dog may be pain free by 12 to 15 months. (Radiographs are not necessaroly recommended at this early stage, since the hips continue to develop through two years of age and the severity of the signs is not always reflected by what is seen on the x-ray films). Older dogs may show acute or chronic pain, especially after prolonged exercise. This may be due to continued progression of hip dysplasia or degenerative joint disease. Radiographs are often helpful for confirmation and to determine the duration of the problem. As with the younger group, confinement and analgesics as needed may be sufficient.

If however, the joint is irreparably affected, surgical correction is the best option; surgical goal is to eliminate abnormal bone contact and create a new smooth joint surface. Abnormal bone pressure is remedied by removing the head of the femur (the ball). To create a new socket, a small muscle is transferred to between the acetabulum and the new surface will be limited in that the limb, but pain is reduced. With gradual build-up, exercise tolerance will return to nearly normal levels. This false joint surface, however, is an abnormal joint and will never be as effective as the original one, especially in heavier dogs (80 pounds or more). If both hips are affected (as over 90%) are), unilateral surgical correction plus medical management is generally sufficient.

^* Breeders who have bred only dogs with radiographically normal hips have decreased the incidence of hip dysplasia (in offspring) without exception! Dog owners who have conformed to a strict schedule of exercise restriction and proper nutritional intake have lessened the severity and progression of early hip dysplasia signs without exception! Nothing we can do, however, will completely limit the occurrence of hip dysplasia in any line or breeds of dogs.

When looking for a new pup always check the Dam and Sire's OFA's. These are x-rays taken of the dogs hips at around age two and will give you a good idea of the shape of the dogs hips.