Cholangiocarcinoma (bile duct carcinoma) has been reported in dogs, cats, sheep, goats and frequently in cattle but not in swine. It is relatively uncommon in all domestic species and comprises less than 1% of all neoplasms in dogs. The incidence of cholangiocarcinoma in dogs estimated to be 1.6 per 100,000 dogs and 0.36% of all neoplasms. This neoplasm arises within the intrahepatic billiary system much more than extrahepatic bile ducts or gall bladder. A 4.5 years old mixed male German shepherd presented with severe abdominal enlargement and vomiting. Clinical examination showed depression, lethargy and deep icterus, liver palpation was not possible because of severe abdominal enlargement, but confirmed presence of fluid in abdominal cavity. Blood chemistry profile was the first laboratory test performed; results showed severe hepatic involvement (high level of hepatic enzymes, hypoalbominemia). Abdominal radiography showed ground glass appearance. Because of loss of owner companionship and severe patient involvement (at the point of death), we were not able to perform other compatible diagnostic procedures, finally decided to euthanize the patient. In necropsy, great amounts of abdominal fluid drained and at first glance a pyknotic multinodular liver (firm) noted. Pathologic examinations showed the cells that retained their resemblance to biliary epithelium but with some pleomorphism and mitotic figure abundance. Some acinar arrangements can be detected among solid masses of neoplastic cells. The epithelial components of neoplasm were separated by fibrous connective tissue. And mucin was present within the neoplastic tubules or acini. All were evidences of cholangicarcinoma.

Finally although this is a rare neoplasm but we should bear it in our minds as one differential diagnosis, and perform more concise (depends on availability of diagnostic instruments) diagnostic approach. In this cases biopsy, ultrasonography and clarifying metstatic state by radiography, May lead us to a better and more concise decision and saving more lives.