Gallbladder agenesis is a congenital absence of the gallbladder. In the absence of congenital malformations of the intrahepatic biliary structures, this is an inconsequential abnormality.
Biliary atresia is a congenital maldevelopment of intrahepatic biliary structures seen uncommonly in dogs. The dog is jaundiced and unthrifty at a young age. Prognosis is poor.
A bilobed gallbladder is occasionally identified in cats during ultrasonography or at surgery. This is an inconsequential abnormality.
Cystic mucosal hyperplasia of the gallbladder is also known as cystic mucinous hypertrophy, cystic mucinous hyperplasia, and mucinous cholecystitis (although it is not an inflammatory lesion). The role of steroid hormones in lesion induction remains unclear. There is no associated inflammation, and the serosal surface of the gallbladder remains intact. These hyperplastic lesions are routinely identified in dogs with gallbladder mucoceles in which the gallbladder wall is often grossly thickened with a proliferative mucosal surface, and a lumen containing thick green, viscous mucoid debris.
Gallbladder dysmotility is proposed as an emerging syndrome in dogs and may precede gallbladder mucocele development. The syndrome may be linked to steroid hormones, based on early observations of an apparent link between mucocele development and treatment with progestational compounds. Furthermore, sex hormones (progestins, androgens) have been shown experimentally (in vitro) to reduce contractility of the gallbladder musculature.
Last full review/revision March 2012 by Sharon A. Center, DVM, DACVIM