Legg-Calve-Perthes Disease Avascular Necrosis of the Femoral Head
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Breeding advice appliesUse the condition’s screening guidance and veterinary or genetics advice before breeding an affected or at-risk animal.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Legg-Calvé-Perthes disease is a developmental disorder of the hip in which the blood supply to the femoral head is disrupted. Without adequate circulation, part of the bone dies, weakens and begins to collapse. The smooth cartilage covering the femoral head is then distorted, and the ball-and-socket joint loses its normal shape. Secondary osteoarthritis follows.
The disease is seen most often in small and toy breeds and is thought to have an inherited component. One hip is commonly affected, although bilateral disease can occur. The loss of blood supply begins while the dog is growing, often around three to four months of age, but obvious lameness is more commonly noticed several months later.
Affected dogs develop progressive hind-limb pain and may initially show only intermittent lameness. As the femoral head collapses, the dog becomes reluctant to bear weight, the hip loses range of motion and thigh muscles shrink from disuse. Pain can eventually become severe enough that the leg is carried most of the time.
Early films may show subtle changes in bone density, while later images reveal flattening, fragmentation and collapse of the femoral head and neck. The pattern distinguishes Legg-Calvé-Perthes from hip dysplasia and traumatic injury.
The disease is not caused by exercise or an owner allowing the puppy to jump. The primary problem is loss of blood supply to developing bone. Once structural collapse has occurred, rest alone cannot restore a normal femoral head. Fortunately, surgical treatment is highly successful in most small dogs and can return them to comfortable, active function when combined with appropriate rehabilitation.
As the weakened femoral head collapses and remodels, the hip joint loses its normal smooth shape and becomes painful. The dog may progressively reduce weight-bearing on the affected hind leg, lose thigh muscle and develop a shortened stride or persistent lameness.
Both hips are assessed because bilateral involvement is possible.
Screening & Early Detection
Routine screening radiographs of all healthy dogs are not generally practical because clinical signs tend to develop soon after radiographic abnormalities become meaningful. In predisposed small breeds, early detection therefore depends on recognising persistent hind-limb lameness during the first year of life.
Watch for reluctance to bear weight on one hind leg, progressive limping, difficulty jumping, pain when the hip is extended or visible loss of thigh muscle. A puppy that repeatedly becomes lame without a clear injury should be examined rather than rested indefinitely.
The veterinarian performs an orthopaedic examination and obtains properly positioned pelvic radiographs. Early changes can be subtle, so repeat imaging may be recommended if clinical suspicion remains high despite an initially inconclusive film.
There is no widely used DNA test that identifies every dog that will develop Legg-Calvé-Perthes disease. Family history and breed prevalence therefore remain important for breeding decisions. A dog that required treatment for the condition should be recorded as affected even if it later moves normally.
Early diagnosis matters because prolonged painful non-use leads to muscle wasting and worsening arthritis. Screening in practice is therefore careful observation of young at-risk dogs and prompt radiography once persistent hip pain or lameness appears.
Diagnosis is made with hip radiographs.
Treatment & Management
In most small dogs, the preferred treatment is femoral head and neck excision. The damaged femoral head is surgically removed so the painful bone-on-bone contact within the malformed hip no longer occurs. Over time, a flexible fibrous “false joint” forms, supported by surrounding muscles. Small dogs generally function extremely well after this procedure.
Rehabilitation is essential. Once the surgeon allows movement, controlled physiotherapy encourages the dog to use the leg and prevents the hip region from becoming stiff. Passive range-of-motion exercises, gradual walking and sometimes hydrotherapy help rebuild thigh muscle. Excessive prolonged rest after the initial healing period can delay functional recovery.
Pain relief is provided around surgery, and body weight should be kept lean to reduce the load on the recovering limb. In rare early cases where collapse has not yet occurred, conservative management has historically been attempted, but the response is unpredictable and progression may still require surgery.
Total hip replacement can be considered in selected larger dogs, where femoral head excision may not provide the same mechanical result as in a toy breed. The surgical choice therefore depends on body size and joint damage.
Prognosis after appropriate surgery is generally excellent, particularly when muscle rehabilitation is started at the correct time. Untreated disease causes persistent pain and arthritis, so a progressively lame puppy should not be managed indefinitely with pain medication alone when a reliable surgical option is available.
Breeds or species affected
Affenpinscher
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Australian shepherd
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Bichon frise
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Border terrier
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Cairn terrier
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Chihuahua
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Pug
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Dachshund
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Wire Fox Terrier
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Lakeland terrier
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Lhasa apso
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Lowchen
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Manchester terrier
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Miniature Pinscher
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Miniature Poodle
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Toy Poodle
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Silky terrier
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West Highland white terrier
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Yorkshire terrier
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