Gallbladder mucocoele (GBM) is an abnormal, intraluminal accumulation of inspissated bile and/or mucous within the gallbladder. Older, small- to medium-breed dogs seem to be predisposed, but no sex predilection has been identified. Clinical signs are often non-specific and include vomiting, lethargy, anorexia, abdominal pain, icterus and polyuria-polydipsia. Results of a complete blood count may be unremarkable, but serum biochemistry usually reveals increased liver enzymes. The ultrasonographic appearance is diagnostic and well described in the literature. Surgical intervention for the treatment of GBM remains the therapeutic gold standard, with short- and long-term survival for biliary surgery being 66%. The worst outcome is seen in those dogs requiring cholecystoenterostomy. With GBM becoming an apparently increasingly common cause of extrahepatic biliary disease in canines, it is essential that clinicians become familiar with the current literature pertaining to this condition. Numerous predisposing factors are highlighted in this review article and the role of certain endocrinopathies (e.g. hyperadrenocorticism and hypothyroidism) in the development of GBM is touched upon. Furthermore, the aetiopathogenesis of this disease is discussed with reference to the latest literature. Cholecystectomy remains the treatment of choice, but other options are considered based on a current literature review.