Hypertrophic osteopathy in a cat with cardiac interventricular septal defect.

A 3-year-old mixed-breed female cat was diagnosed with a ventricular septal defect of the heart through an echocardiogram. After a 9-month treatment, progressive and diffuse hard thickening of all limbs was observed, which on radiographic examinations, revealed a marked thickening of the long bones. The necropsy findings were limited to the appendicular skeleton and thoracic vertebrae, in addition to a severe cardiac interventricular septal defect and lung edema. The histological evaluation revealed severe replacement of the cortical bone by spongy bone in all bone fragments examined. This is the first report of hypertrophic osteopathy occurring in association with a cardiac malformation in a cat.