To determine the effect of flushing of the common bile duct (CBD) on hepatobiliary markers and short-term outcome in dogs undergoing cholecystectomy for the management of gallbladder mucocele (GBM). Randomized, controlled, prospective study. Thirty-two client-owned dogs. Dogs were allocated randomly to either a "flush" group or a "non-flush group." Flushing was performed in a normograde fashion, followed by a routine cholecystectomy. Data collected included presenting clinical signs, preoperative and 3-day postoperative hepatobiliary markers (alkaline phosphatase, ALP; alanine aminotransferase, ALT; gamma glumatyl-transferase, GGT; bilirubin; cholesterol; triglycerides), duration of hospitalization, and complications. These data were compared between groups. Sixteen dogs were enrolled in each group. One dog (in the flush group) was excluded following diagnosis of hepatic lymphoma. Border terriers were overrepresented (20/31). Overall, there were marked reductions from preoperative to 3 days postoperative in serum bilirubin (p = .004), ALP (p = .020), ALT (p < .001), GGT (p = .025), and cholesterol (p < .001) values. There was no difference in any marker between groups. Survival to discharge was 90.3% (28/31 dogs). Cholestatic markers decreased significantly 3 days postcholecystectomy. No short-term clinical or clinico-pathological benefits were identified when flushing the CBD in dogs undergoing cholecystectomy for GBM. The findings of the study do not support routine flushing of the CBD during cholecystectomy for GBM in dogs.