Isolated right-ventricular hypertrophy associated with severe pulmonary vascular apolipoprotein A1-derived amyloidosis in a dog.

A 12-year-old dachshund was referred for respiratory distress, coughing, and weight loss. Cyanosis, dyspnea, tachypnea, and harsh lung sounds were noted on physical examination. Polycythemia with an increased number of nucleated red blood cells; right atrial enlargement; severe interstitial-to-alveolar pattern in all lung fields; and peripheral, echogenic, pulmonary masses were observed. Cytological examination of pulmonary aspirates indicated possible pulmonary carcinoma. The dog was euthanized at the owner's request. Isolated right-ventricular hypertrophy and pulmonary arteriopathy with amyloid deposits of apolipoprotein A1 were identified upon necropsy and histopathology. Pulmonary vascular amyloidosis should be considered in the differential diagnoses of respiratory distress in aged dogs.