Legg-Calve-Perthes disease

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Radiographic view of femoral necrosis in a dog with Legg-Calve-Perthes disease

Legg-Calvé-Perthes disease (femoral avascular necrosis) is a multifactorial genetic disease of small-breed dogs characterized by osteonecrosis of the proximal femoral epiphysis and secondary osteoarthritis.

This disease occurs almost exclusively in toy- and miniature-breed dogs[1].

The cause of this disease is unknown, but various theories have been promulgated such as genetic predisposition, osteomyelitis, trauma and metabolic and hormonal imbalances. However, vascular abnormalities seems likely as small toy-breed dogs have particularly narrow vascular channels through which the superior retinacular vessels reach the epiphyseal plates[2], and repeated trauma may well induced subclinical synovitis resulting in perfusion disturbances within the epiphysis[3].

As the disease progresses, there is mechanical collapse, asymmetric growth, and disturbed enchondral ossification at the growth plate, leading to degenerative changes that can be visualized radiographically.

Clinical signs usually manifest as an intermittent unilateral hindlimb lameness which presents at 4 - 6 months of age or older and progressively worsens over time. Recent trauma may be evident, and the affected leg may show signs of muscle atrophy due to disuse. Males and females are equally affected and bilateral involvement occurs in only 12% to 16% of cases[4].

Diagnosis is usually based on confirmatory changes to the femoral head, characterized by degenerative joint disease, bone lysis, osteoarthritis and osteophyte formation.

A differential diagnosis would include hip dysplasia (usually large-breed dogs), panosteitis and hypertrophic osteodystrophy.

Treatment in most cases requires excisional arthroplasty (removal of the femoral head), which is often curative of clinical signs.

References

  1. Vasseur PB et al (1989) Mode of inheritance of Perthes' disease in Manchester terriers. Clin Orthop Relat Res 244:281-292
  2. Fujikawa K (1991) Comparative vascular anatomy of the hip of the miniature dog and of the normal-size mongrel. Kurume Med J 38(3):159-165
  3. Lucht U et al (1983) Blood flow in the juvenile hip in relation to changes of the intraarticular pressure. An experimental investigation in dogs. Acta Orthop Scand 54(2):182-187
  4. Warren DV & Dingwall JS (1972) Legg-Perthes disease in the dog: A review. Can Vet J 13(6):135–137