What is Legg-Calve-Perthes Disease?
Also referred to as Necrosis of the Femoral Head in Dogs – This condition is additionally known as Legg-Calve-Perthes Disease, Calve-Perthes disease, Legg-Perthes disease, Perthes disease, coxa plana, osteochondritis juvenilis and aseptic or avascular necrosis of the femoral head.
The femur is the bone that joins with the pelvis to form the hip joint, known as the coxofemoral joint. The hip is a ball-and-socket joint, with the “ball” being the head of the femur and the “socket” being the acetabulum of the pelvis. In Legg-Calve-Perthes Disease, there is a disruption of the blood flow to the femur. As a result, the cells of the bone begin to die, and the head and neck of the femur become necrotic. The exact cause of the loss of blood flow is unknown, but theories include hormonal influence, anatomic conformation, an increase in pressure, or some other cause of compression to the fragile blood vessels of the joint.
What types of dogs get Legg-Calve-Perthes Disease?
Legg-Calve-Perthes disease is a condition of small breed dogs. The most commonly affected breed is the Yorkshire Terrier, but it is also seen in West Highland Terriers, Manchester Terriers, as well as many other small and toy breeds. The age of onset is typically around 6 or 7 months, but could be present as early as 3 months, or as late as 13 months of age. Both males and females are equally affected. In dogs with Legg-Calve-Perthes disease, 10-17% of them have it in both hind limbs.
What are the Signs of Legg-Calve-Perthes Disease?
Owners typically bring their dog in for evaluation of a weight-bearing lameness that appears slowly, and gradually worsens over a period of 6-8 weeks. As the lameness worsens, the dog may become non-weight bearing. In some cases, the lameness may be acute due to a sudden collapse of the diseased bone. Over time, as the animal continues to favor the affected limb, muscle atrophy becomes apparent. Legg-Calve-Perthes disease is a painful condition. In affected dogs, pain may manifest as irritability, decreased appetite, and chewing at the skin over the affected hip. Pain, decreased range of motion, and a grating sound is often noticeable when the hip is manipulated. The condition becomes especially painful if the degradation of the bone results in fracture of the femoral head.
How does a veterinarian diagnose Legg-Calve-Perthes Disease in dogs?
Diagnosis is based on clinical signs and medical history. The most common clinical signs are slowly progressing hind limb lameness, with resulting inability to bear weight on the affected limb or both hind limbs. It may begin in one leg and progress to both legs, especially in young pets. On clinical examination there is usually reduced hip joint movement, lack of muscle mass and apparent limb shortening. Owners often report that their pet has become increasingly irritable. The diagnosis is made by taking x-rays of the hips. If legs-calve-perthes disease is present in the cat or dog, the x-rays will show a deformity of the femoral head, shortening or lysis (destruction) of the femoral neck and areas where the bone is less dense than normal. The head of the femur may appear moth-eathen and/or flattened and there is an increase in the joint space.
How did my dog get Legg-Calve-Perthes Disease?
The cause of Perthes’s disease is still largely unknown. It may be a hereditary condition of small breed young dogs, especially terriers. We also occasionally see it occur in cats. It is common after trauma or injury to the leg or hip. We do know that Legg-Calve-Perthes disease is caused by compromised blood flow to the femoral head and neck. However, the exact reason for that loss of blood flow is still unknown. Some researchers believe that it can be due to the presence of sex hormones at an earlier age than normal or from injury resulting in damage to the blood vessels. It has been reported that there is a genetic cause for the disease, an autosomal recessive gene that is inherited from both parents.
How is Legg-Calve-Perthes Disease Treated in dogs?
The treatment of choice is femoral head and neck ostectomy (FHO) or removal of the femoral head and neck. Because the condition often affects young, small breed dogs, it is often unnecessary to replace the hip joint. Larger dogs with Legg-Calve-Perthes disease may require a total hip replacement. A femoral head and neck ostectomy (FHO) procedure involves making an incision over the hip region and then the joint is exposed and the femoral head and neck are removed. There is no need to secure the cut bone, because as it heals, fibrous tissue will form in the region so that bone doesn’t rub against bone and the muscles hold the hip in place. The difference with having and FHO versus other orthopedic procedures is that activity is not restricted after surgery. In fact, it is encouraged because it will help maintain range of motion in the joint and strengthen the muscles. Exercises however need to adhere to a strict rehabilitation protocol specifically designed for your dog by a veterinarian or physiotherapist. You can read more about our Post-op rehabilitation and home care instructions for FHO surgery HERE.
Conservative treatment consisting of strict cage rest and physical therapy is generally only successful in a small percentage of patients, and only if the femoral head still has its normal shape and is tightly seated in the socket. Monthly radiographs should be made until the pet is 1 year of age. However, most dogs require surgical intervention to alleviate the pain and lameness associated with Legg-Calve-Perthes disease.
What happens to the joint if part of the hip is removed?
Healing involves the laying down of fibrous tissue and in a very short time a false joint is created. Within months, most dogs are running and playing as if nothing happened.
Do complications occur with FHO surgery on dogs?
Complications are rare following this type of surgery. A small percentage of dogs will always experience some limping or discomfort and may require long-term anti-inflammatory medication. Others may require a second surgery to remove any residual bone spurs that may cause discomfort.
Can Legg-Calve-Perthes Disease be Prevented in dogs?
Legg-Calve-Perthes disease has been linked to an inherited gene. Therefore, the best method of prevention is not breeding animals diagnosed with this disease.
What is the Prognosis for my Dog with Legg-Calve-Perthes Disease?
Most dogs start to bear weight about 2 weeks after surgery and by 2-3 months recovery is complete. Femoral head osteotomy produces much more favorable results than conservative treatment. Dogs improve better, and have a shorter recovery period. With the proper surgical technique, virtually 100% of these animals will become ambulatory and free of pain. Physical therapy is recommended to ensure proper healing and a normal range of motion of the hip. A slight limp may remain because the leg is shortened by removal of the femoral head and neck, but usually this doesn’t cause any functional problems or pain.
If my dog is diagnosed with Legg-Calve-Perthes disease, Can I still breed my dog?
Since this is often a hereditary condition, we do not recommend breeding any dog diagnosed with Legg-Calve-Perthes disease.