Aseptic necrosis, a deterioration of the femoral head seen in young miniature and small breeds of dogs, is associated with ischemia and avascular necrosis of the bone. The exact cause is unknown, although there may be a hereditary component in Manchester Terriers. Infarction of the bone leads to collapse of the femoral head and neck, followed by revascularization, resorption, and remodeling. The lesion is often bilateral.
Clinical signs include hindlimb lameness, atrophy of the thigh muscles, and pain during manipulation of the hip joint. Radiography reveals irregular bone density of the femoral head and neck, collapse, and fragmentation of the bone. Chronic cases have evidence of degenerative joint disease.
Treatment involves surgical excision of the affected femoral head and neck and early postoperative physical therapy to stimulate limb usage. Prognosis for recovery is excellent.