High-output heart failure secondary to severe chronic anaemia in a dog

An 11-year-old, 4.8-kg, entire, male Papillon dog presented because of anaemia and polyuria-polydipsia for 2 months before presentation and sudden dyspnoea. Haematological examination revealed severe non-regenerative anaemia. Thoracic radiography revealed pulmonary oedema and cardiac enlargement. Echocardiography showed no obvious structural cardiac abnormalities; however, the left ventricular preload and cardiac output were high, and the systemic vascular resistance was low. The dog was diagnosed with high-output heart failure secondary to non-regenerative anaemia. Fresh whole blood transfusion following the treatment of congestive heart failure using diuretics and supplemental oxygen was performed. After 5 days, the high-output heart failure had markedly improved and the clinical signs had resolved; therefore, bone marrow cytological examination was performed, and the patient was diagnosed as presumed pure red cell aplasia. To the best of our knowledge, this is the first report of naturally occurring high-output heart failure secondary to severe chronic anaemia in dogs.