Dogs with intrahepatic shunts have more severe signs at an earlier age, probably related to the larger volumes of blood diverted through the shunt as compared to extrahepatic shunts. Portoazygous or portophrenic shunts may be associated with less severe clinical signs, and consequently, may not be diagnosed until later in life. In rare instances, 2 or more vascular communications may be present. Single extrahepatic PSS are more common in cats and small or toy breed dogs. Single intrahepatic PSS are most common in large and medium-sized breeds. Acquired PSS, which form in response to portal hypertension, are typically multiple extrahepatic shunts connecting the portal system and the caudal vena cava.Ĭongenital PSS are typically single and may be intrahepatic or extrahepatic. The genetic basis for congenital PSS is unknown, although in Yorkshire and Cairn terriers, inheritance is not simple dominant, simple recessive, or sex-linked. Affected lines of Irish wolfhounds and Cairn terriers have also been described. Yorkshire terriers are the most commonly reported breed with congenital PSS. Congenital PSS are anomalous embryonal vessels that usually occur as single shunts and are not associated with portal hypertension. The congenital form is most commonly recognized. Portosystemic shunts in dogs and cats can be either congenital or acquired. Urolithiasis may be a complication in as many as 50% of animals with congenital PSS. Urate urolithiasis, an important complication of PSS, occurs because of increased urinary excretion of ammonia and uric acid. Decreased hepatic blood flow and lack of hepatotrophic factors result in hepatic atrophy. Signs of hepatic encephalopathy (HE) dominate the clinical picture because of inadequate hepatic clearance of enterically-derived toxins. Portosystemic shunts (PSS) are vascular communications between the portal and systemic venous systems that allow portal blood to access the systemic circulation without first passing through the liver.
0 kommentar(er)
