Complications after surgical attenuation of congenital extrahepatic portosystemic shunts in dogs can be prevented by intraoperative Doppler ultrasonographic assessment of portal hemodynamics

Abstract

Under normal circumstances the blood from the gastrointestinal tract flows via the portal vein to the liver. The detoxified blood leaves the liver via the hepatic veins to the caudal vena cava, which latter enters the heart. Portosystemic shunting occurs when an anomalous vein allows the portal blood to bypass the liver. This can happen via acquired portosystemic collaterals as a consequence of sustained portal hypertension or via a congenital portosystemic shunt (CPSS) as a result of a developmental anomaly. Congenital portosystemic shunts have been described in several mammals including humans, however the only species in which the anomaly is fairly common is the dog. Although there are several anatomic variations of the anomalous vessels a CPSS is always a large-bore vein that drains almost 100% of the portal blood to a systemic vein. The most common type of CPSS in dogs is the so-called spleno-caval shunt, which is an extrahepatic vessel that drains the portal blood via a splenic vein segment to the caudal vena cava.