Gallbladder mucoceles in Shetland Sheepdogs

Gallbladder mucocele (GBM, Gallbladder mucoceles) is a disease characterized by an excessive production of bile with a thick gelatinous consistency. The accumulation of this pathologically altered bile in the gallbladder results in its rupture and spillage of bile into the abdominal cavity. The resulting inflammation of the abdominal cavity is very painful for the patient and can be fatal. Common non-specific clinical signs include vomiting, lethargy, abdominal pain, anorexia, jaundice, rapid breathing, thirst and frequent urination, fever, diarrhoea, and bloating.

This disease is found in the Sheltie, American Cocker Spaniel, Cairn Terrier, German Spitz-Pomeranian and English Cocker Spaniel. It is caused by a mutation in the ABCB4 gene. It is a G insertion (c.1660_1661insG) that shifts the reading frame and generates four stop codons that prematurely terminate the synthesis of the ABCB4 protein in exon 12 and thus disrupt its function.

The inheritance of the mutation is still unknown. The mutation was thought to be dominant with incomplete penetrance, nowadays a multifactorial mode of inheritance and a non-hereditary aetiology are discussed.

.

References:

Mealey, K.L., Minch, J.D., White, S.N., Snekvik, K.R., Mattoon, J.S. : An insertion mutation in ABCB4 is associated with gallbladder mucocele formation in dogs. Comp Hepatol 9:6, 2010. Pubmed reference: 20598156