Primary pulmonary adenocarcinoma with brain stem metastasis in a dog.

Primary pulmonary adenocarcinoma with metastatic spread to the brain stem was diagnosed at necropsy in an aged Bulldog. Initial clinical signs included coughing, decreased exercise tolerance, and personality changes. Primary differential diagnoses after thoracic radiography were multicentric metastatic neoplasia or fungal disease. Later clinical signs (inappetence, unilateral facial paralysis and decreased sensation, and hemiparesis) were referable to the effect of the tumor on cranial nerves V and VII and other brain stem structures. Primary lung tumors are uncommon, as are metastatic tumors within the CNS. Radiographic appearance alone of lung lesions is insufficient for accurate diagnosis.