Liver tumors in cats and dogs

Tumors affecting the liver can be either primary or metastatic. Metastatic involvement is more common than primary hepatobiliary tumors. The four categories of primary hepatic tumors in cats and dogs are hepatocellular, bile duct, mesenchymal, and neuroendocrine. In dogs, malignant variants of these tumors are more common, whereas benign neoplasia, particularly cystic bile duct adenoma, is more frequent in cats. Primary hepatic tumors are morphologically classified as massive, nodular, or diffuse. The prognosis is better for massive tumors than for nodular, diffuse, or metastatic liver tumors because surgical resection is possible and can be curative, particularly for hepatocellular carcinoma in dogs and bile duct adenoma and myelolipoma in cats. In contrast, treatment options are limited for cats and dogs with nodular, diffuse, and metastatic liver tumors as surgery is often not possible and other forms of therapy have not been investigated.