Mucinous Pleural Effusion in a Dog with a Pulmonary Adenocarcinoma and Carcinomatosis

An 11 yr old castrated male greyhound presented to the Washington State University's Veterinary Teaching Hospital (WSU VTH) for evaluation of a 4 day history of pleural effusion. The pleural effusion had a gelatinous appearance, suggestive of mucus, and was characterized cytologically as a pyogranulomatous exudate with some features suggestive of a carcinoma. Postmortem examination identified a pulmonary mass with evidence of carcinomatosis. Pulmonary papillary adenocarcinoma with carcinomatosis was the histologic diagnosis. Abundant mucin production was present, consistent with a mucinous pulmonary adenocarcinoma. To the authors' knowledge, this is the first report of a mucinous pulmonary adenocarcinoma with mucus pleural effusion in a dog.