Unknown age, spayed female mixed dog was presented with a severe lethargy. Radiography, ultrasonography, and blood screen test were performed to make a diagnosis. There were no specific radiographic findings. On the ultrasonography, small amount of ascites was found around gallbladder and hepatic vein was dilated approximately 6.1 mm. Blood screen test revealed a severe anemia. Result of heartworm ELISA kit was positive. At necropsy, parasites were in the left atrium, right ventricles, aorta, pulmonary artery, right renal artery.