Pleural mesothelioma in a California sea lion (Zalophus californianus).

A 25-year-old female California sea lion (Zalophus californianus) reared in an aquarium died following a history of anorexia, lethargy, abnormal protrusion of the skin, and oral respiration. At necropsy, multiple yellowish-white nodules with diameters of 0.1-0.