Dog: Legg-Perthes Disease

Other common/scientific names: aseptic necrosis of the femoral head, avascular necrosis of the femoral head

The hip joint consists of the head of the femur (thigh bone) and the acetabulum of the pelvis. It is a ball and socket type of joint with the ball portion of the joint being the rounded head of the femur which fits into socket portion of the joint or the acetabulum.

Legg-Perthes disease results when the blood supply to the femoral head is interrupted. Portions of the bone begin to die due to lack of blood and the overlying cartilage collapses leading to bone to bone contact and arthritis of the hip joint.

While infection and trauma can damage the blood supply to the hip, Legg-Perthes disease is thought to be inherited. It is most commonly seen in small breeds with terriers, miniature pinschers and toy poodles being more predisposed.

Lameness

Dogs with Legg-Perthes disease initially show pain and lameness of the affected joint. They may cry in pain when the leg is stretched or bearing weight. As the disease progresses, the dog may become unable to bear weight on the affected leg and the muscles of the thigh and hip will shrink from disuse. Signs are most commonly seen in young dogs, aging five to twelve months of age. One or both hips can be affected.

Legg-Perthes disease is diagnosed by radiographs of the hips.

Abb. GG92Y2X0: Legg-Perthes disease.

This is a radiograph showing a diseased femoral head of the hip joint. The arrow points to the necrotic bone.

Anti-inflammatories and exercise restriction will provide temporary relief for Legg-Perthes disease. However, for most cases, surgery is the treatment of choice. Small to medium sized dogs will undergo a femoral head and neck ostectomy (FHO) which is the removal of the diseased femoral head or ball and the femoral neck. This eliminates the source of pain and creates a false joint consisting of a cushion of scar tissue between the cut bone edge and the hip socket. Large dogs may need total hip replacement surgery.

Pain medications and anti-inflammatories are given postoperatively.

Abb. GG930PUB: Legg-Perthes disease after surgery.

This is a radiograph of a hip which has undergone a femoral head and neck ostectomy. The arrow points to area where the diseased femoral head and neck were removed.

Abb. GG932MSJ: Post Surgery.

This is a photograph of a dog post surgery for Legg-Perthes disease. Note the incision over the hip joint.

The prognosis is good for small to medium sized dogs. Most of these dogs return to good, pain-free mobility postoperatively. Large dogs have a more guarded prognosis.

Legg-Perthes disease cannot be prevented. However, dogs diagnosed with Legg-Perthes disease should never be used for breeding.

Moderate physical activity should be encouraged post surgery to help strengthen the muscles of the hip and leg. Physiotherapy exercises may also be of benefit.