Five dogs at the age of 2-13 years, with variant respiratory signs like as dry cough, dyspnea, exercise intorelance and lameness were presented. On thoracic radiographs, all dogs had abnormalities such as soft tissue density, round mass image, increased pulmonary infiltration and pleural effusion. All dogs were diagnosed as adenocarcinoma on cytopathologic examinations by fine needle aspiration with ultrasound guidance. Computed tomography was performed in three cases to evaluate clinical stage. Primary papillary adenocarcinoma was confirmed after necropsy in one case.