A gall bladder mucocoele was diagnosed in a 13-year-old Yorkshire terrier. The dog was referred for acute onset lethargy, diarrhoea, and vomiting, with cranial abdominal pain on palpation. Blood biochemistry was suggestive of extra-hepatic biliary tract disease; however ultrasonographic examination provided a definitive diagnosis of gall bladder mucocoele. A cholecystectomy was performed.

Gall bladder mucocoeles are an obstructive extra-hepatic biliary tract disease characterized by the abnormal accumulation of mucous that distends the gallbladder; the etiology is still unclear.

The diagnosis of mucocoeles is ultrasonographic, and treatment is surgical. Cholecystectomy is the most commonly reported surgical technique for the treatment of gall bladder mucocoeles. Surgical removal is considered an emergency procedure if there is a suspicion of mucocoele rupture.
Appropriate and timely diagnosis and treatment should enable an excellent prognosis with complete resolution of symptoms and biochemical disturbances, provided there are no postoperative complications.

Key words: mucocele, gallbladder, cholecystectomy, obstructive extrahepatic biliary disease (extrahepatic biliary tract disease)