Legg-Calve-Perthes disease, (LCPD) is idiopathic avascular necrosis (AVN), or osteonecrosis of the top of the femur (femoral head). An insufficient blood supply to the head of the femur (top of the thigh bone) causes this section of bone to die and disintegrate. This results in the deterioration of muscles associated with the area, and reduces the mobility of the hip joint.
Diagnosis of Legg-Calve-Perthes Disease
The diagnosis of Legg-Calve-Perthes disease is essentially a radiological one. Corticosteroid medication is a pivotal risk factor in the development of avascular osteonecrosis. Conditionally, it may cause the disease. The pathogenetic mechanisms involved in steroid-induced osteonecrosis are poorly understood. First recognized after short-term, high-dosed steroid therapy in occasional patients, most cases are diagnosed after long-term treatment.
Signs of Legg-Calve-Perthes Disease
The main clinical sign in Legg-Calve-Perthes disease (LCP) is severe lameness in one or both hindlegs due to pain within the hip joint. This can sometimes be caused by injury to the area, however, in LCP this pain and lameness is not associated with an injury and is due to this inherited disorder. Lameness in an affected dog will usually become evident at four to ten months of age. An early sign may be irritability when picked up or groomed over the hindquarters. The dog may favor the affected leg, and sometimes refuse to bear weight on it. Generally, within two months of initially favouring the leg, the dog will not support itself at all with the limb. Other signs include moderate to severe pain on passive movement of the joint - especially when the leg is pulled away from the body - and, when the legs are extended, the affected limb may appear shorter. X-rays of the limb will reveal an irregular bone density, and a flattening of the head of the femur, indicating the disintegration of bone.
The advantages of knowing which breeds of dogs are at increased risk for Legg-Calve-Perthes Disease are evident. It can heighten awareness among breed club members, helping them make decisions about how to spend their foundation dollars, and it can lead to more emphasis being placed on methods to diagnose and genetically screen for the disease in that breed before animals are bred and genes are recycled to the gene pool.
Breeds at Risk for Legg-Calve-Perthes Disease
Australian shepherd, Cairn terrier, Chihuahua, Dachshund, Lhasa apso, Miniature pinscher, Miniature poodle, Pug, Toy poodle, West Highland white terrier, Yorkshire terrier. (Source: Breed Susceptibility for Developmental Orthopedic Diseases in Dogs. Elizabeth LaFond, DVM, Diplomate ACVS, Gert J. Breur, DVM, PhD, Diplomate ACVS and Connie C. Austin, MPH, PhD)