DIABETES-MELLITUS IN A KOALA (PHASCOLARCTOS-CINEREUS)

Objective To describe a case of diabetes mellitus in a koala (Phascola rctos cinereus). Design A case report with controls. Procedures We des cribe clinical and laboratory findings in a 6-year-old, free-living, f emale koala presented with traumatic injury and subsequently found to have polydipsia, hyperglycaemia and glucosuria. Over a 5 week period, serum biochemical analyses, haematological examinations, urinalyses, m easurement of serum insulin and fructosamine concentrations, necropsy, histopathological examination of a range of tissues and immunohistoch emical examination of the pancreas for insulin-containing cells were d one. For reference purposes, serum insulin and fructosamine concentrat ions were determined in four and two healthy koalas, respectively, and three healthy koalas' pancreases were examined histologically and imm unohistochemically. Results The koala had persistent hyperglycaemia, h yperlipidaemia, hyponatraemia, hypochloraemia and glucosuria. Serum in sulin concentration of the diabetic koala was only marginally smaller than that of healthy koalas, but all concentrations were smaller than reference concentrations in dogs and people. Fructosamine concentratio n did not allow the diabetic koala to be distinguished from healthy ko alas and concentrations of all koala analytes were greater than expect ed for healthy dogs and people. Histopathological examination revealed extensive degeneration of pancreatic islet cells and fatty infiltrati on of hepatocytes. Immunoperoxidase staining revealed decreased or abs ent insulin in the beta cells of the affected koala. Conclusion Clinic al signs, clinicopathological results and histopathological changes we re consistent with diabetes mellitus. The pathogenesis of the conditio n could not be determined but may have been related to the administrat ion of a parenteral corticosteroid preparation, the stress of capture or tissue damage and inflammation.