Older companion animals may be uncommonly affected with hepatobiliary neoplasia. If clinical signs are shown they are often nonspecific. Animals may have increased liver enzyme activities detected on serum biochemistry. Ultrasound imaging can help to characterize liver lesions and guide sampling with fine needle aspiration. Treatment for massive liver tumor morphology involves liver lobectomy. Prognosis depends on the tumor morphology, type, and stage, but can be good for cats and dogs with massive hepatocellular tumors, with animals experiencing prolonged survival and low recurrence rates.