RESUMEN
Due to climate restrictions in parts of North America and Europe, koalas (Phascolarctos cinereus) are housed indoors. Koala young (joeys) raised indoors are susceptible to the development of metabolic bone disease (MBD) due to a lack of exposure to natural ultraviolet light to themselves and their female parents (dams). In this retrospective study, radiographs from 27 koala joeys born at four zoos in North America and two zoos in Europe were evaluated for signs of MBD. Eight of the joeys were radiographically diagnosed with MBD and four additional joeys were considered suspect MBD cases; in two joeys absence or presence of MBD could not be determined. All joeys had mild to severe hip and shoulder dysplasia. There were significant associations between a lack of exposure to UV light and MBD development and between MBD and the degree of severity of hip and shoulder dysplasia. It is recommended to house breeding female koalas and their joeys outdoors whenever possible.