Canine Extrahepatic Biliary Tract Disease and Surgery

gallbladder and biliary tree is low compared with the many parenchymal hepatic conditions that occur in animals. Diseases of the extrahepatic biliary system are often confused with other intraabdominal disorders because their course and clinical signs are similar. Diseases that require surgery of the extrahepatic biliary system in dogs are primarily acquired and include extrahepatic biliary tract obstruction (EHBO), traumatic injury, and cholecystitis. The main goals of surgery are to confirm the underlying disease process, establish a patent biliary system, and minimize perioperative complications. This article reviews the common disorders of the extrahepatic biliary system in dogs, including common clinical signs, typical c linical pathologic findings, surgical procedures, and common surgical complications. ANATOMY AND PHYSIOLOGY OF THE BILIARY SYSTEM The canine extrahepatic biliary system comprises the gallbladder, cystic duct, hepatic ducts, bile duct, and major duodenal papilla (Figure 1). In dogs, bile flows from the bile canaliculi into the interlobular ducts and then the lobar ducts before leaving the liver. Lobar ducts drain into hepatic ducts, through which bile passes into the common bile duct. The gallbladder lies within a fossa between the right medial and quadrate lobes of the liver. The gallbladder is drained by the cystic duct and is the portion of duct before the hepatic ducts enter the common bile duct (Figure 2). In a medium-sized dog (33 to 44 lb [15 to 20 kg]), the gallbladder holds approximately 15 ml of bile. In dogs, the common bile duct terminates near the minor pancreatic duct at the major duodenal papilla (Figure 2). In a medium-sized dog, the common bile duct is approximately 5 cm long and 2.5 mm in diameter and empties