Hip dysplasia is a congenital disease that, in its more severe form, can eventually cause lameness and painful arthritis of the joints. It is caused by a combination of genetic and environmental factors. It can be found in many animals and, rarely, humans, but is common in many dog breeds, particularly the larger breeds.

Description

In the normal anatomy of the hip joint, the thigh bone (femur) joins the hip in the hip joint, specifically the caput ossis femoris. The almost spherical end of the femur articulates with the hip bone acetabulum, a partly cartilaginous mold into which the caput neatly fits. It is important that the weight of the body is carried on the bony part of the acetabulum, not on the cartilage part, because otherwise the caput can glide out of the acetabulum, which is very painful. Such a condition also may lead to maladaptation of the respective bones and poor articulation of the joint.

In dogs, the problem almost always appears by the time the dog is 18 months old. The defect can be anywhere from mild to severely crippling. It can cause severe osteoarthritis eventually.

Causes

In dogs, there is considerable evidence that genetics plays a large role in the development of this defect. There might be several contributing genetic factors, including a femur that does ot fit correctly into the pelvic socket, or poorly developed muscles in the pelvic area. Overfeeding puppies and young dogs, particularly in the giant breeds, might aggravate the problem or bring it on earlier because of rapid growth. Overexercising young dogs whose bones and muscles have not yet fully developed might also be a contributing factor.

Symptoms

Dogs might exhibit signs of pain, lameness, reluctance to exercise, and wasting away of the muscle mass in the hip area. Most dogs do not show symptoms--and x-rays do not reveal the presence--of hip dysplasia until at least a year of age, although some dogs manifest the problem early and others do not show it until as old as two years.

Treatment

There is no complete cure, although surgery can alleviate the symptoms. Depending on the extent of the problem, surgical alternatives include excision arthroplasty, in which the head of the femur is removed and reshaped or replaced; pelvic rotation, in which the hip socket is realigned; or hip replacement, which has the highest percentage of success.

Responsible breeders who track the incidence of hip dysplasia have been able to reduce the incidence in some breeds but not to eliminate it altogether.

References

• Siegal, Mordecai (editor); UC Davis School of Veterinary Medicine Book of Dogs, 1995. Harper Collins. ISBN 0-06-270136-3.

External links

• Orthopedic Foundation for Animals