Antebrachial Fractures in Four Captive Polar Bears (Ursus maritimus)

Abstract

To identify common risk factors for antebrachial fractures of captive polar bears and to evaluate outcome after fracture repair. Retrospective study. Four captive polar bears. United States zoological collections were surveyed to determine the prevalence of fractures in captive polar bears. Medical records of captive polar bears that had antebrachial fractures were reviewed for signalment, history, physical and radiographic findings, fracture management, postoperative care, and outcome. Serum samples from healthy bears and bears with antebrachial fractures were assayed for 25-hydroxyvitamin D (25-OHD) concentrations. Nineteen fractures (12 polar bears) occurred from 1974 to 2002; 12 fractures involved the antebrachium. Management of 4 antebrachial fractures was reviewed; 3 were repaired by internal fixation and 1 by external coaptation. Fractures healed and bears were returned to exhibit on average 3 months postfracture. Of 11 serum samples assayed for 25-OHD concentrations, 6 were below normal, 1 was low normal and 4 were within normal reference intervals. The 7 bears with subnormal or low normal values were housed in 2 zoos. Subnormal vitamin D concentrations were identified in 2 of 3 bears with fractures. Fracture disease is not uncommon in captive polar bears. Additional research is necessary to explore the role of nutrition in polar bear fracture disease. Internal fixation of antebrachial fractures is feasible and reasonably well tolerated in captive polar bears.