Ultrasonographic identification of Dirofilaria immitis in the aorta and liver of a dog.

A 5-year-old sexually intact male mixed-breed dog was evaluated because of suspected vena caval syndrome secondary to heartworm disease. On physical examination, the dog was thin, icteric, and weak and had tachycardia and a cardiac murmur. Serum biochemical and hematologic abnormalities included hyperbilirubinemia, high serum alkaline phosphatase and alanine transferase activities, hypoalbuminemia, leukocytosis, and normocytic normochromic anemia. Dirofilaria immitis microfilariae were seen in a blood smear. Echocardiography was used to confirm the diagnosis of vena caval syndrome. Multiple aberrant adult heartworms were evident ultrasonographically in the abdominal aorta and its branches and within hypoechoic nodules in the left caudal lobe of the liver. The dog's condition deteriorated despite supportive treatment and retrieval of 58 adult heartworms from the right side of the heart and vena cava, and the dog was euthanatized. At necropsy, adult heartworms were found in the aorta and inflammatory hepatic nodules. To our knowledge, ultrasonographic identification of heartworms within the systemic arterial system and liver of a dog has not been described previously.