Endogenous lipid pneumonia in a brown bear (Ursus arctos).

A free-living yearling male brown bear (Ursus arctos) was observed in the wild, exhibiting marked ataxia, and died shortly after undergoing a standard immobilization procedure. The brown bear is a strictly protected species in many countries, including Poland, under both national and international legislation, as well as several conservation agreements. Autopsy revealed marked gross changes in the lungs. Histopathological examination showed multifocal infiltration of foamy macrophages within the alveolar and bronchiolar lumen. The presence of Sudanophilic vacuoles within macrophages supported a diagnosis of lipid pneumonia. Large extracellular Sudanophilic droplets were also observed. No indications of concurrent pulmonary infection were identified histologically. Infectious causes were excluded using bacteriological, parasitological and molecular analyses. Only single cases of endogenous lipid pneumonia have been reported in non-domestic animals, with most cases involving captive individuals. In the reported case, the bear was free-living and encountered in the wild. To our knowledge, this is the first documented case of lipid pneumonia in a free-living brown bear.