Dog Legg-Calve-Perthes Syndrome

Legg-Calve-Perthes Disease (LCP Disease) is a congenital (present at birth) degeneration of the bone end. LCP disease of the hip joint that results in abnormal deformity of the ball of the hip joint, caused by the disruption of the blood supply to the head of the femur (the round bone which fits into the hip socket). Legg-Calve-Perthes Disease have different names but refers to the same disease: Calve-Perthes disease, Legg-Perthes disease, Avascular necrosis of the femoral head, Coxa plana or Osteochondritis juvenilis.  Legg-Calve-Perthes results when the blood supply to the femoral head is interrupted, resulting in the death of bone cells. This is usually followed by a period of revascularization, where the femoral head is subject to remodeling and/or collapse, creating an irregular fit into the hip socket. This process of bone cells dying and chipping followed by new bone growth and the remodeling of the femoral head and neck, leads to stiffness and pain in the rear leg or legs.

Legg-Calve-Perthes disease is common in miniature, toy breeds and many other small breed dogs and affects the hip joints of dogs in the ages of 4 to 12 months old. Poodles, Yorkies, Lakeland terriers, west Highland white terriers, Jack Russell terriers and miniature pinchers just to name a few of mostly affected by this syndrome. Sometimes easily mistaken for hip dysplasia is Legg Calvé Perthes disease. The immediate cause of bone death is loss of blood supply. Both sexes are affected, but males suffer 4 times more often than females. This is an avascular (pertaining to inadequate blood supply), aseptic (not infected), developmental osteonecrosis (dying of bone tissue) of the femoral head and neck, found almost entirely in toy or other small breeds. It can be described as a localized tissue anemia. On radiographs, it often looks as if the bone is rotting away, and lameness with variable pain is the major or only symptom. A young dog affected with this disease will gradually develop pain and lameness in 1 hind leg, which slowly worsens over 3 or 4 weeks. The pain will become quite severe, and there is usually muscle shrinkage (atrophy) in the affected leg. In the rare cases where both hips are affected, the dog will sometimes "bunny-hop". As the disease progresses, the dog may suspend the affected limb in the air, and may or may not exhibit pain when the leg is flexed. In very mild cases, often no symptoms are apparent, while in severe cases; the dog can be in great pain and become very irritable.

Diagnosis is accomplished through radiographs (X-rays) of the hips, often done under light anesthesia. Depending on how far the disease has progressed, there may be muscle wasting (atrophy) in the affected limb. Radiographs will show whether your dog has the characteristic features of this disease, and also if there are other bony degenerative changes to the hip. Diagnosis is confirmed with a bone biopsy. Radiographic (X ray) signs of Legg Perthes are usually gross and discouraging, as many cases are not referred to the vet or the specialist for diagnosis until the dog has been limping for a long time or the disease has progressed to the point that it becomes a more real problem to the owner. These small dogs put so little weight on their tiny hip joints that they almost can compensate for discomfort by walking on their forelimbs instead of their four limbs.

There are two approaches in treating this disease: conservative therapy and surgical operation. Conservative treatment with strict cage rest and physical therapy could be successful only if the femoral head is still has its normal shape and is is tightly seated in the socket; monthly radiographs should be made until the pet is 1 year of age. The animal is carried to and from the cage and kept on a leash during evacuation. Strict adherence to this form of treatment results in a dog with nearly normal femoral head (bone end) and complete return of pain-free motion and a normal gait. It takes 4 to 6 months before the femoral head heals sufficiently to permit normal movement.

Surgical Operation. Many dogs have advanced cases of this disease by the time they are examined by a veterinarian and medical treatment is not likely to work. In these dogs, excision of the femoral head (ball portion of the hip joint) is often beneficial. Removal of this section of the bone diminishes painful bony contact in the hip joint. Recovery from this surgery can be slow with recovery periods of up to one year sometimes occurring before good use of the affected leg returns. If muscle atrophy is not present at the time of surgery the recovery time is usually much less. Pain relief and anti-inflammatory medications may be beneficial. Femoral head and neck excision is the treatment of choice if the radiographs show deformity of the femoral head or looseness of the hip joint; this surgery involves removing the femoral head and neck.     

Usually excellent, and within several months, the dog can again walk and run. In some cases, the affected leg may remain slightly shorter and the muscles may be somewhat atrophied. Some veterinarians feel there may be an increased risk of arthritis as the dog ages.