Hepatic arteriovenous fistulae and portal vein hypoplasia in a Labrador retriever

An 18-month-old male Labrador retriever was referred for investigation of c hronic intermittent diarrhoea and vomiting of two months duration. A diagno sis of hepatic arteriovenous fistulae was made. These are extremely rare he patic vascular anomalies which confer arterial pressure to the portal vein. Liver atrophy, portal vein hypoplasia, portal hypertension and multiple ac quired portosystemic collateral vessels are the main complications. Surgica l excision is a challenge as resection of large lesions may be associated w ith significant blood loss. In this dog, persistence of portal vein hypopla sia and extensive collateral pathways following surgery led to a reserved p rognosis.