HYPERTROPHIC OSTEOPATHY CHARACTERIZED BY NUCLEAR SCINTIGRAPHY IN A HORSE

A five year old American Saddlebred gelding was admitted to the Univer sity of Illinois Veterinary Medical Teaching Hospital with a history o f multiple leg lameness, depression and intermittent fever for a durat ion of six months. Physical examination revealed the horse to be under weight, depressed and afebrile. No abnormalities were detected during auscultation of the heart and lungs. All limbs possessed multiple hard swellings of the distal long bones and digits. The horse walked with a stiff gait and was reluctant to trot. Nuclear scintigraphy of the di stal limbs revealed multiple areas of focally increased uptake in all limbs. Radiographs of several sites on the distal limbs showed evidenc e of periosteal new bone production corresponding to the areas of abno rmal uptake. The horse was euthanized and at necropsy chronic, multifo cal, fibrous pericarditis and epicarditis were observed grossly. The l eft atrial myocardium contained areas of osseous metaplasia. Histologi cal evaluation of the distal long bones revealed proliferative periost eal new bone formation consistent with a diagnosis of hypertrophic ost eopathy.