SURGICAL APPROACHES TO SINGLE EXTRAHEPATIC PORTOSYSTEMIC SHUNTS

Single extrahepatic portosystemic shunts (PSSs) are routinely diagnose d during exploratory laparotomy. a thorough, systematic approach must be followed to locate the aberrant vessel. The caudal vena cava must b e carefully evaluated for dilation, turbulent flow, and termination of abnormal shunting tributaries. Extrahepatic PSSs can also join the ca udal vena cava from unusual vessels, such as colic veins, or can trave rse the diaphragm and insert on the azygos vein. If a PSS cannot be id entified during abdominal exploration, the practitioner should perform a liver biopsy and mesenteric portography to assist in making a diagn osis. Although extrahepatic PSSs can be occluded surgically, the prehe patic portal vein must be present to ensure a return of hepatic portal blood flow. Use of ameroid constrictors for gradual, complete shunt l igation has decreased morbidity and mortality rates. Because veterinar ians, owners, and breeders are increasingly aware of the clinical sign s of PSS, diagnosis is becoming more common. It is thus important for practitioners to be knowledgeable about the techniques currently used for definitive diagnosis and treatment of PSS. E-Familiarity with the anatomic structures involved with PSSs (particularly the abdominal ven ous system) is critical in identifying and surgically correcting them.