Transient high-output heart failure documented by echocardiographic cardiac index measurement in a pregnant cat.

A female cat (approximately 3 weeks of gestation) was referred for respiratory distress and pleural effusion. Echocardiography revealed dilation of the left atrium and left ventricle, and the cardiac index was markedly elevated (0.39 L/kg/min), raising suspicion for high-output heart failure (HOHF). The cat was treated with furosemide and enrofloxacin. Pleural effusion completely resolved in late pregnancy, and 45 days after delivery the cardiac index decreased to 0.22 L/kg/min. To our knowledge, this is the first report describing a transient HOHF associated with pregnancy in a cat, highlighting the clinical utility of echocardiographic cardiac index measurement for identifying this condition. Further accumulation of cases is needed to better characterise this condition in feline patients.