Liver Tumors

What is it?

A liver tumor is an abnormal growth of cells in the liver. Primary tumors (those that start in the liver) are rare; more often, cancer spreads to the liver from elsewhere. In dogs, hepatocellular carcinoma (HCC) is the most common primary liver tumor, followed by bile duct carcinoma. Tumors may form one large mass, several nodules, or spread through the whole liver. They tend to occur in pets older than about nine years, and no specific cause is known.

What signs should I watch for?

Some dogs show no signs. Others have poor appetite, fever, lethargy, weight change, nausea, vomiting, diarrhea, increased drinking and urination, or yellowing of the skin and eyes (jaundice). Occasionally there are seizures, disorientation, stumbling, or weakness. Sudden weakness, collapse, pale gums, and trouble breathing can mean a tumor has ruptured and is bleeding into the abdomen.

How is it diagnosed and treated?

Your veterinarian may feel an enlarged liver or a mass, or find rising liver enzymes on repeat blood tests. Ultrasound is the most sensitive way to find liver masses; CT or MRI is sometimes used. A needle sample or, more accurately, a core-needle biopsy identifies the tumor type. Surgery, removing the tumor or the affected liver lobe, is the treatment of choice for most single masses, and the liver can regrow after a large portion is removed. Chemotherapy has a less defined role, and newer options such as chemoembolization exist for some inoperable tumors.

Can it be prevented, and what's the outlook?

• There is no known prevention.
• Benign tumors and single large HCCs that can be removed have a good to excellent outlook.
• Bile duct carcinomas, neuroendocrine tumors, and sarcomas, which tend to spread, have a guarded to poor outlook.