Legg-Perthes disease is a hip joint disease that can occur in both dogs and cats. It involves disintegration of the head of the femur, which is the ball of the hip joint. When the femoral head disintegrates due to a loss of blood supply, it results in disfigurement of the hip joint as well as bone and joint inflammation (arthritis). This can be extremely painful for a pet, but fortunately, the prognosis after treatment is usually very good.
Legg-Perthes disease also goes by some other names: Perthes disease, Legg-Calve-Perthes Disease, Legg’s disease, coxa plana, and aseptic or avascular necrosis of the femoral head.
Causes of Legg-Perthes Disease in Dogs and Cats
The causes of Legg-Perthes disease are not well understood. There is likely a strong genetic component because the disease tends to show up in young, small breed, or miniature breed dogs -- especially terriers. It can also occur in cats, and may become apparent after an injury or trauma to the leg or hip.
Disintegration of the femoral head occurs when blood supply to the area is interrupted. An interruption in blood supply -- also known as “ischemia” -- causes the bone and surrounding cartilage to disintegrate and die. When this happens, the area around the affected hip joint becomes irritated and inflamed. Eventually, the hip becomes disfigured and collapses, and is no longer able to carry weight.
Legg-Perthes disease can appear in both hip joints simultaneously or only in one.
Symptoms of Legg-Perthes Disease in Dogs and Cats
The initial symptoms of Legg-Perthes disease often appear in pets less than one year old. As the disease progresses, so too will the symptoms, and they typically include:
- Progressive hind leg lameness
- Pain when moving affected limb(s)
- Muscle disintegration on affected limb(s)
- Difficulty rising, sitting, jumping, and running
- Exercise intolerance
- Chewing or licking the affected limb(s)
- “Clicking” sound from affected limb(s)
Diagnosing Legg-Perthes Disease in Dogs and Cats
The symptoms of Legg-Perthes disease can mimic those of many other conditions, including hip dysplasia, arthritis, and injury or fracture. Your veterinarian will need to rule out these conditions and diagnose Legg-Perthes disease through a physical examination, a discussion of symptoms, and testing. Testing may include complete blood work, urinalysis, and x-rays. X-rays help your veterinarian to diagnose Legg-Perthes disease by revealing problems such as a widening of the area between the femoral head and the pelvic socket, bone fragmentation, irregular femoral structure, and abnormal bone density.
Treatment for Legg-Perthes Disease in Dogs and Cats
Some pets with mild or early forms of the disease may respond well to a combination of bed rest, physical therapy, pain-relief medications, corticosteroids, and non-steroidal anti-inflammatory drug (NSAIDS).
In most cases, however, surgery will be necessary. The procedure of choice is a femoral head and neck ostectomy, which involves removal of the femoral head and neck. This allows for the formation of a “false joint” made up of fibrous tissues, granulation tissues, and scar tissues. These tissues essentially replace the ball-and-socket joint of the hip.
In the rare case of a large dog with Legg-Perthes disease, a total hip replacement may be necessary. This is an expensive and complicated procedure that involves removing the entire damaged joint and replacing it with an artificial femoral head and hip joint socket.
With both procedures, post-operative care is extremely important, and you should follow your veterinarian’s instructions about bandaging, cold compresses, and activity restriction. Most pets will also require physical therapy following surgery, and diet should be carefully monitored to avoid obesity, which can put stress on the joints.
In addition to the above treatment options, there are some less traditional treatments that have proven to be beneficial in some pets with Legg-Perthes disease. They include:
The prognosis for pets treated surgically is very good if the pet receives appropriate postoperative care and rehabilitation. After recovery, most pets return to their normal selves and are able to run, jump, and play.
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