Introduction
Legg-Perthes disease (also called aseptic necrosis of the femoral head, Legg-Calve-Perthes disease, or simply Perthes disease) is a painful hip condition that results in degeneration and necrosis of the head of the femur (the long upper leg bone that joins the pelvis to form the hip joint). For some unknown reason, the normal blood supply to that very upper part of the femur bone is spontaneously disrupted, without trauma, causing the affected bone and cartilage to fracture, disfigure, collapse, and try to remodel as the dead and dying tissues are reabsorbed by the body.
Legg-Perthes disease occurs most commonly in young, small-breed dogs of either gender, and only occasionally in larger dogs. Affected breeds include several of the small terriers (Yorkshire, Manchester, Lakeland, West Highland White, Cairn), small poodles (toy and miniature), Chihuahuas, Dachshunds, Pugs, Miniature pinschers, Australian shepherds and Lhasa apsos.
Clinical signs involve varying degrees of progressive hind limb lameness – usually in one leg (unilateral) but it can appear in both (bilateral) – together with pain and muscle atrophy.
Treating Legg-Perthes Disease
Fortunately, despite the increasing severity of Legg-Perthes disease, successful treatments are available. The treatment choice depends largely upon the size of the dog, the gravity of clinical signs and the degree of tissue and bone deterioration that is present.
The therapeutic goal for dogs suffering from Legg-Perthes disease is a return to pain-free activity, with hip function hopefully being as normal as possible. In mild cases, dogs may respond to non-surgical treatment involving activity restriction and intermittent or chronic administration of oral pain and nonsteroidal anti-inflammatory medications (these are called “analgesics” and “NSAIDs,” respectively). Cage rest and physical therapy may also be used. However, surgical treatment has a much higher rate of success than does only medical management.
In most cases, surgery ultimately will be necessary. The most common surgical procedure is a femoral head and neck excision (also called an ostectomy). This involves surgically removing the head and usually the upper neck of the femur bone. This allows a fibrous “false joint” to form, replacing the abnormal ball-and-socket joint of the affected dog’s hip(s).
Another surgical option is a total hip replacement, where the damaged joint is removed and an artificial femoral head and hip joint socket are implanted. This is most frequently used in uncommonly large dogs that are affected by Legg-Perthes disease. The procedure requires tremendous technical skill and should only be done by a veterinarian who specializes in such surgeries.
Post-operative bandaging and activity management are important to rehabilitation and recovery from either of these surgeries. Physical therapy is especially important to rehabilitating the affected limb, including early vigorous exercise after surgery. Small lead weights may be attached above the hock joint as “anklets” to encourage leg use. Swimming is also often recommended. Owners must manage their dogs’ diet carefully to prevent obesity. Affected dogs should not be bred.
While these surgical procedures may sound somewhat drastic, most dogs achieve very good to excellent return of leg and hip function with proper post-operative physical therapy and are able to enjoy normal, pain-free canine activities such as running, jumping and walking throughout a normal life span.