Caroli Syndrome in a 6-Year-Old Rottweiler Dog

A 6-year-old entire female rottweiler dog with a recent history of ascites and respiratory disease was submitted for necropsy examination. The dog had been diagnosed ultrasonographically with biliary cysts as a puppy. Grossly, the liver was smaller than expected with an irregular surface. Islands of hepatocytes were separated by bands of fibrosis and many bile ducts were markedly dilated. Histologically, extensive fibrosis extended beyond the limiting plate and into the surrounding hepatic parenchyma and was associated with abundant small bile ducts throughout. In conjunction with the detection of biliary cysts early in life, the gross and histological findings were consistent with a diagnosis of Caroli syndrome. In man, Caroli syndrome is frequently associated with renal and pancreatic cysts; a single renal cyst was identified in this case.