Portosystemic Shunts - The University of Tennessee College of ...

Brief Overview ofPortosystemic ShuntsWhat is a Liver Shunt?A liver shunt is a blood vessel that carries blood aroundthe liver instead of through it. In some animals a livershunt is a birth defect (“congenital portosystemicshunt”). In others, multiple small shunts (“acquiredportosystemic shunts”) form because of severe liverdisease such as cirrhosis.“Congenital PSS and MVDare related genetic disorders causingmalformation of the liver circulation.”—CenterWhy do animals with shunts have problems?In the normal animal, food and other ingestedmaterials are broken down or digested in the intestinesand absorbed into the portal blood stream, where theyare carried to the liver. The liver stores some of the foodfor energy, processes some of it into safe chemicals, anduses some of it to make proteins and other substances.Because the blood bypasses the liver in dogs withshunts, toxins may build up in the bloodstream orkidneys. Additionally, the animal lacks the necessarymaterials to give it a ready source of energy and to helpit grow.What are the most common types ofPortosystemic Shunts (PSS)?There are a number of types of portosystemic shunts.Those present at birth are classified as “congenital.”1. Single extrahepatic shunt: a single shunting vesselthat is located outside the liver. This is the mostcommon type of congenital shunt.2. Single intrahepatic shunt: a single shuntingvessel within the liver. These are congenital andmost commonly seen in large-breed dogs.3. Extrahepatic multiple acquired shunts: Whenblood pressure in the portal system becomes toohigh, multiple small blood vessels will open up toshunt blood around the liver. Multiple acquired shuntsoccur as a result of end stage liver disease (cirrhosis)and portal hypertension. These are not congenital andthey are not surgically correctable.1