Abstract. One hundred ten primary hepatic neoplasms, excluding hematopoietic and vascular tumors, were diagnosed in 12,245 canine necropsies. Included were 55 hepatocellular carcinomas, 24 bile duct carcinomas, 2 combined hepatocellular and cholangiocarcinomas, 15 carcinoids and 14 sarcomas. A majority of the dogs with hepatocellular carcinoma (80%), bile duct carcinoma (65%) and sarcoma (61%) were 10 years old or older; 71% of the dogs with carcinoid were under 10 years old. Hepatocellular carcinoma and sarcoma occurred more often in males, bile duct carcinoma in females, and no sex predisposition was found in dogs with carcinoid. All dogs had hematologic and biochemical abnormalities relating to liver function. The aspartate amino transferase/alanine amino transferase ratio was less than one in cases of hepatocellular carcinoma and bile duct carcinoma, and more than one in cases of carcinoid and sarcoma. A massive lesion in one of the liver lobes was the most common gross morphologic feature in cases of hepatocellular carcinoma and bile duct carcinoma, with the left lateral lobe affected most often. In cases of carcinoid, most of the lesions were diffuse. The most common sites of metastases were lymph nodes and lungs for hepatocellular carcinoma and bile duct carcinoma, lymph nodes and peritoneum for carcinoid, and spleen for sarcoma.Neoplasms of the liver and biliary tracts are uncommon in domestic animals [3,6,15,16,22,23,26,31, 361. Frequency in the dog vanes from 0.6% to 1.3% of all neoplasms [6,9,15,16,18,31,33]. Only a few studies deal with the clinicopathologic features of a large number of canine primary hepatic neoplasms [4, 12,14,15,28,31,331.
Materials and MethodsCase records and histologic specimens from dogs with hepatic neoplasms seen between 1962 and 1977 at The Animal Medical Center were reviewed. AU cases with enough slides to confirm the diagnosis were included in the study. Details of the 110 dogs' clinical and gross pathologic fmdings were collected from the medical and necropsy records. Because neoplasms arising from the hematopoietic and vascular systems usually involve several organs, they were excluded from this study. Hepatocellular adenoma, intrahepatic bile duct adenoma and bile duct cyst adenoma also were excluded because of their high frequency and because of the difficulty in distinguishing between nodular hyperplasia and hepatocellular adenoma.The hepatic neoplasms were grouped under hepatocellular carcinoma, bile duct carcinoma,
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