Spontaneous capital femoral physeal fracture in cats
2-year-old overweight domestic shorthair male cat, neutered at 4 months, with progressive right pelvic limb lameness and no known trauma. Pain on hip extension. On the ventrodorsal radiograph the right capital femoral physis is still open, the epiphysis is displaced and the femoral neck shows lysis and remodelling.
What is the most likely diagnosis?
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A. Legg-Calvé-Perthes disease
It is avascular necrosis of the femoral epiphysis typical of small-breed dogs. It causes mottled lysis and collapse of the head, not separation through a physis that remains open in an adult.
B. Hip dysplasia
Feline hip dysplasia causes a shallow acetabulum, subluxation and osteoarthritis, mainly at the craniodorsal acetabular rim. It does not explain an open physis at 2 years with epiphyseal displacement.
C. Proximal femoral osteosarcoma
An aggressive lesion is possible at any age, but in a young cat with an open physis and a remodelled femoral neck the picture fits a physeal fracture much better. If in doubt, histopathology of the excised head will clarify it.
D. Spontaneous capital femoral physeal fracture (slipped epiphysis)
Correct. It is typical of young, overweight, neutered male cats. Early neutering delays physeal closure, and the open physis fractures under normal loads. Resorption of the femoral neck is characteristic.
lightbulb Key takeaway
Always radiograph both hips: the condition is often bilateral, even if only one side is clinical. Femoral head and neck excision usually gives a good outcome. In neutered cats physes can stay open far longer than expected: do not mistake them for fractures in other bones.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.