Introduction
Although the disease has been recognized for several decades, the incidence of gallbladder (GB) mucoceles (MCs) in dogs appears to have rapidly increased over the last 20 years (Malek et al.
2013). GB MCs are now considered the most common causes of extrahepatic biliary disease in the canine patient and the most common reason for performing biliary surgery in this species (Hottinger 2014). Whether this apparent increase is as a result of increased awareness of the disease together with early detection by improved abdominal ultrasonography, or a true increase in incidence of the disease, is still unknown (Malek et al. 2013).A GB MC is defined as accumulation of mucous and inspissated bile salts within the fundus of the GB causing GB distention. The MC develops because of the progressive accumulation of tenacious, mucin-laden bile in the GB, which may extend into the cystic duct, common bile-duct, and hepatic ducts. This accumulation leads to pressure ischemic necrosis of the GB or cystic duct wall, opportunistic bacterial infections and potentially GB or cystic duct/common bile duct rupture with subsequent bile peritonitis (Hottinger 2014). On histopathology, it is characterized by cystic mucinous epithelial hyperplasia of the GB wall with inflammatory infiltrates but rarely with an infectious etiology being recognized. Grossly a MC appears as an accumulation of shiny green-black gelatinous material with lamellar striations within the GB lumen.