The pathology of a case of biliary atresia in a foal.

The pathological features of biliary atresia in a foal are described. A 4-week-old American Saddler foal was presented for autopsy following an illness characterised by clinical features indicative of hepatic failure. The significant macroscopical lesions occurred in the liver which was extremely enlarged, mottled in appearance and indurated. Bile stasis was evident. Lobular distinction was absent and on sectioning, large bile ducts were absent. A moderate ascites, hydrothorax and hydropericardium and a mild anasarca and intermuscular oedema accompanied the hepatic lesion. The diagnosis of biliary atresia was determined by the histopathological features of bile duct proliferation and extensive replacement fibrosis. The condition is compared to extrahepatic and intrahepatic biliary atresia of man and evidence is presented for regarding this case to be one of extrahepatic origin.