Tumors of the liver in cattle, sheep and pigs

This paper describes a series of primary tumors of the liver parenchyma and biliary tract in cattle, sheep and pigs which were examined during a 12-mouth survey of neoplasms found in 100 abattoirs throughout Great Britain. In cattle 302 tumors were studied, 36 of which arose in the liver. Cholangiocarcinomas outnumbered liver cell tumors. In sheep 32 of 107 tumors originated in the liver, with liver cell tumors more numerous than cholangiocarcinomas. Primary liver tumors were of a comparatively low incidence in pigs—only six in 139 neoplasms. There were no cholangiocarcinomas in pigs though one adencarcinoma of the gallbladder was found. Secondary tumors outnumbered primary liver tumors in cattle and pigs while the converse was true in sheep. Of the secondary tumors involving liver, lymphosarcoma predominated in the three species. Malignancy of liver cell tumors was difficult to assess in the absence of obvious metastases; however, most of the liver cell tumors were apparently benign while the great majority of the cholangiocarcinomas had metastasized to lymph nodes, peritoneum and lung. There was no significant association between primary hepatic tumours and the presence of any pre-existing disease process.