Gallbladder mucoceles are an uncommon yet likely underdiagnosed condition of the canine extrahepatic biliary system. Although unclear, the cause is associated with cystic mucinous hyperplasia of the gallbladder wall producing viscous mucus that is unable to exit the gallbladder during normal physiologic contraction. Mucus accumulation may result in obstruction of the common bile duct, leading to extrahepatic biliary tract obstruction and/or progressive gallbladder distention and potential rupture.

To identify prognostic factors for future treatment, 43 dogs with gallbladder mucoceles treated by cholecystectomy were retrospectively evaluated. Older, medium-sized dogs were overrepresented with consistent signs (eg, vomiting, anorexia, lethargy); ultrasonographic findings consistent with gallbladder mucocele were documented in most. Postoperative increased serum lactate values and hypotension were the only prognostic factors negatively associated with survival. Histologic evidence of gallbladder wall necrosis was evident in 25% of cases, many of which suggested rupture at surgery. Positive bacterial culture of bile was noted in 1 case. Mean survival was 20 months for dogs that survived the perioperative period, with the remaining 23% of cases succumbing to associated disease within 2 months.

Commentary
Gallbladder mucoceles should be considered a differential diagnosis for presentation of vague GI distress, particularly in overrepresented breeds (eg, cocker spaniel, Shetland sheepdog, miniature schnauzer). Diagnosis can be accomplished via ultrasonography (kiwi-like appearance within gallbladder lumen). Treatment decision involves the optimal timing for surgical intervention. Further confounding the recommendation for surgery is when these are noted as incidental findings.

Only postoperative prognostic factors were identified in this study. Other previously reported negative prognosticators (eg, presence of bacterial infection or gall-bladder necrosis) did not impact survival. The role of other interim approaches to increase perioperative survival, including placement of temporary biliary drainage catheters1 or medical management of cholestasis using liver protectants,2 deserves further investigation. Survival following cholecystectomy beyond the short-term postoperative period remains relatively good.—Jason Bleedorn, DVM, DACVS

Source
Clinical findings and prognostic factors for dogs undergoing cholecystectomy for gall bladder mucocele. Malek S, Sinclair E, Hosgood G, et al. VET SURG doi: 10.1111/j.1532-950X.2012.01072.x.

1. Minimally invasive cholecystostomy in the dog: Evaluation of placement techniques and use in extrahepatic biliary obstruction. Murphy SM, Rodriguez JD, McAnulty JF. Vet Surg 36:675-683, 2007.

2. Nonsurgical resolution of gallbladder mucocele in 2 dogs. Walter R, Dunn ME, d’Anjou MA, Lécuyer M. JAVMA 232:1688-1693, 2008.