Causes of Legg-Perthes Disease
Legg-Perthes disease in domestic dogs is considered to be “idiopathic” – which means that it has no known cause. It tends to occur in young, small or miniature-breed dogs of either gender and is thought to have a strong genetic component. For some reason, the normal blood supply to the upper part of the femur bone becomes disrupted, without any recognizable precipitating traumatic event. Interruption of the blood supply (called “ischemia”) causes the affected bone and surrounding cartilage to degenerate, deform, fracture and die. The entire area around the affected hip joint becomes irritated, inflamed and increasingly painful. Once the cells of the upper part of the femur die, they start to be replaced by fibrous and granulation tissues that are not as strong as bone. The body tries to revascularize the area and remodel the dead and dying bone and cartilage as it is reabsorbed by the body, but these attempts are not successful. This degenerative process causes the hip joint to become disfigured, lose its structural integrity and become non-weight-bearing. Eventually, the hip collapses. Legg-Perthes disease can show up bilaterally (in both hip joints) or unilaterally (in just one).
Preventing Legg Perthes Disease
Most reputable authorities agree that dogs diagnosed with Legg Perthes disease should be spayed or neutered, to try and prevent propagation of dogs with this likely inherited disorder. Breeders should also be discouraged from repeating matings that produced affected offspring.
The outlook for dogs with Legg Perthes disease is good. Even if surgery is needed, most dogs are able to enjoy a long and active life with minimal restrictions on physical activities.