Have Cat Questions? Ask a Cat Vet Online.
Avascular necrosis of the femoral head, aseptic femoral head necrosis, or Legg-Calve-Perthes disease is a disorder of the blood supply to the femoral head, the "ball" of the hip joint. It usually occurs in miniature and toy breeds of dogs between the ages of four months and a year of age in its classic form but sometimes occurs as a traumatic problem in older dogs or bigger breeds. It causes death of the bone which leads to arthritis of the hip. Since hip dysplasia also causes hip problems the conditions could be confused, although clinically evident hip dysplasia is not a major problem in dogs of this size. It is usually possible to rule in or rule out femoral head necrosis through radiographic (X-ray) examination.
Femoral head necrosis is a painful process and may be a cause of subtle lameness to total lameness affecting one or both rear legs. Some dogs are able to recover on their own with just rest and pain relief but many dogs require surgical removal of the femoral head (femoral head ostectomy) for good long term pain relief. This can be done on both sides, if necessary, in the small dogs who have this problem.
Let me know if you still have questions.