The extrahepatic bile passages consist of the hepatic ducts from the liver. In human, there is a right and a left hepatic duct draining the right and left part of the liver. But in animal, this system vary considerably between species, the terms right hepatic duct and left hepatic duct, as listed in the VIth NAV is mainly adapted to the horse and ruminants.
In the carnivores, each hepatic sublobe has its own lobar duct which drains into the cystic dug.In dogs, six extrahepatic ducts stem from each hepatic lobe, which is divided into the following 6 lobes in dogs: the left lateral and medial, right lateral and medial, caudate and quadrate lobes.
In the pig, the lobar ducts of the left hepatic lobes unite to form the left hepatic duct, while the ducts of the right lobes drain separately into the common hepatic duct.