Abdominal mesothelioma in an aged guinea pig (Cavia porcellus).

An adult, male guinea pig died of Bordetella bronchiseptica pneumonia during quarantine and was necropsied, Numerous, firm, pale nodules were found attached to the omentum, the parietal peritoneum, and the serosal surface of the liver and intestinal tract. Gross, light, and electron microscopic examination revealed the tumors to be mesotheliomas. To our knowledge, mesotheliomas have not been reported in this species.