A case of primary papillary disseminated adenocarcinoma of canine lung.

Primary lung tumors are rare in dogs, whereas pulmonary metastatic neoplastic involvement is common. We describe a case of a 12-year-old male, mixed-breed dog with a 3-month history of coughing and dyspnea. The investigating protocol, which also includes transcutaneous pulmonary biopsy, allowed a diagnosis of lung adenocarcinoma that necroscopic findings confirmed as a primary neoplasia. The tumor exhibited a nodular-disseminated growth, mimicking the metastatic involvement of the lung, instead of the single-mass appearance that has been observed by other authors. The present report indicates that, although the incidence of canine primary lung neoplasms is markedly low, this condition must be considered in the differential diagnosis of lung diseases that cause coughing and dyspnea in older dogs.