There are multiple soft tissue masses in the pulmonary parenchyma, including the caudal subsegment of the left cranial lung lobe, right cranial lung lobe, and right middle lung lobe. The cranial mediastinum is widened and increased in opacity, indicating lymphadenopathy. The increased soft tissue opacity and widening of the main stem bronchi indicate hilar lymphadenopathy.
Multiple pulmonary masses and lymphadenopathy are characteristic of histiocytic sarcoma. The Bernese Mountain Dog is predisposed to this disease. Lymphoma can manifest a similar lymphadenopathy, however the pulmonary infiltrate is usually a diffuse, interstitial pattern. Granulomatous disease is also less likely to cause pulmonary masses.
Since this disease is often multicentric, abdominal ultrasound is warranted.