Avascular Necrosis - Aseptic Necrosis - Perthes Disease
In some toy breeds, the Poodle and the West Highland White Terrier in particular, the blood vessels serving the head of the femur (in the hip joint) are prone to injury. If these vessels are damaged the head of the femur effectively dies. This is called avascular necrosis and usually occurs between four and 12 months of age.
Diagnosis and treatment
There is usually a loss of muscle mass on the affected leg, although if the disease occurs in both hips, which happens occasionally, the muscle loss is symmetrical. Avascular necrosis is diagnosed by x-ray. This painful condition is treated by surgically removing the dead (necrotic) head of the femur. This eliminates pain. In the following months a "false" fibrous joint develops that is surprisingly efficient.