(Also known as AVASCULAR NECROSIS OF THE FEMORAL HEAD)
Avascular necrosis of the femoral head is a disease of the hip joints of miniature and toy breeds of dogs, most often in Poodles, Yorkies, Lakeland terriers, west Highland white terriers, Jack Russell terriers and miniature pinchers just to name a few. It develops between 4 and 12 months of age. The blood supply to the neck of the femur is inadequate, leading to bone destruction in the hip joint, resulting in a roughened, irregular joint surface. Moving the rear legs causes pain, and the leg muscles weaken and shrink from insufficient use. Occasionally the limbs actually shorten. One or both rear legs may be affected. If only one leg is involved, the dog usually refuses to bear any weight on that limb.
Avascular necrosis is hereditary and probably results from breeding for small body size. This selective breeding produces dogs that mature more rapidly, and the early effects of hormones on the developing hips may cause the disease. Some researchers also believe that injury to the developing hips may cause the condition. If the condition is not treated, the dog may develop severe arthritis in later life. Usually, lameness is so severe that treatment is mandatory.
Lameness and pain on movement of the affected leg. Pain can be localised to the hip joint on examination.
Xrays of the hips will show bone destruction of the femoral neck on the affected side.
Important Points in Treatment
Medical treatment: This is designed to relieve pain and discomfort during recovery in mild cases. NSAID painkillers are the treatment of choice. Joint supplements such as glucosamine are also beneficial.
Surgical treatment: 'Excision arthroplasty', or 'femoral head and neck excision', is the surgical removal of the ball portion (femoral head) of the ball and socket hip joint. Crucial to the outcome is also the successful removal of the neck portion. It is used to treat moderate to severe cases. A "false joint" of fibrous tissue then forms. This often increases both comfort and mobility. Mild exercise is advisable immediately after surgery, but keep your pet restrained on a leash.
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