Tumors in the liver (also known as hepatic neoplasia) may be malignant (cancer) or benign. Cancer found in the liver can originate there (primary) or spread (metastasize) to the liver from malignant tumors elsewhere in the body (secondary - more common in dogs).
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Tumors are classified based on the embryonic origin of the cancerous cells they contain, determined by microscopic analysis of the tumor biopsy. The prefix “-hepato” (liver) may be added to give the formal name of the cancer, e.g., hepatocarcinoma.
Benign liver tumors:
Malignant liver tumors:
Primary liver cancer is not common in dogs, accounting for only 1-3% of canine tumors. Most primary liver cancer seen in dogs is hepatocellular carcinoma or biliary carcinoma (carcinoma of the bile tract, which moves bile from the liver to the small intestine).
Primary liver cancer can spread to other organs, such as the lungs. Secondary cancers in the liver may have metastasized from cancers in a number of different organs including the pancreas, mammary glands, adrenal glands, intestine or thyroid.
Signs and Symptoms
Signs are similar to those of other liver diseases where there is loss of liver function. Because the liver has a lot of reserve capacity, signs are often only seen after a large part of the liver is damaged. Signs may include:
- Pale gums
- Decreased appetite
- Swelling of the abdomen (ascites)
- Jaundice Weight loss
If the cancer in the liver started in another organ, there may also be signs from the original cancer.
Primary liver cancer is thought to be caused by toxins. Because one of the liver’s functions is detoxification of substances filtered from blood, it is exposed to anything ingested and absorbed into the bloodstream.
Secondary liver cancer is due to metastases (spread) of cancer from another area of the body.
Exposure to toxins (primary liver cancer).
Cancer in another area of the body (secondary liver cancer).
A differential diagnosis must differentiate liver cancer from other liver diseases, such as infection or parasites. Diagnosis must also differentiate between benign and malignant tumors, and primary or secondary cancer.
- Physical examination with palpation of abdomen to feel for masses (can detect enlarged liver)
- Blood tests to evaluate liver function and “liver enzymes” (AP or ALP and ALT)
- Blood count - this can show unusual cells in some types of liver cancer
- X-rays and ultrasound can detect masses but cannot tell definitively whether they are malignant or benign.
- Ultrasound guided fine needle aspirate - however, pre-surgery fine needle aspirates differ from surgical biopsy results approximately 20% of the time
- Most definitive test is an ultrasound guided core biopsy (large bore needle) or a biopsy taken at the time of tumor removal.
Decreased liver function may lead to prolonged bleeding times. Prior to a core biopsy or liver surgery, a veterinarian may recommend that a coagulation profile be performed.
Note: Treatment of animals should only be performed by a licensed veterinarian. Veterinarians should consult the current literature and current pharmacological formularies before initiating any treatment protocol.
If the cancer is primary and just in one lobe it can often be treated by surgical removal of the lobe. A dog can survive after removal of more than half the liver since the liver has a large reserve capacity. Unfortunately, this same reserve makes it possible for liver cancer to exist and grow for a long time before signs are seen.
The location of the tumor within the liver must be considered prior to surgery; if tumor is near the major blood vessels there is more risk of bleeding/death from the surgery itself.
Chemotherapy is not very effective for treatment of primary liver cancer.
Prognosis - if the cancer is also in other organs, prognosis is poor, and management may be limited to easing discomfort. Transfusions may be used if there is anemia.
Some recommend SAM-e (S-adenosylmethionine), an amino acid, to “support” the liver. Preliminary research shows some positive effects.
Hepatic Neoplasia, Merck Veterinary Manual
Good discussion of why fine needle aspirates may not yield accurate results: Eves NG. Hepatocellular adenoma in a 12-year-old crossbred German shepherd dog. Can Vet J 2004. 45:326-328.
Wypij J, Fan TM, Lorimier, L-P. Primary hepatic and biliary tract tumors in dogs and cats: An overview. Veterinary Medicine 2006.
These support groups are for all types of canine cancer:
This is a blog dedicated to Canine Liver Disease:
(see also related links at the bottom vetinfo webpage)
Wypij J, Fan TM, Lorimier, L-P. Definitively diagnosing hepatobiliary tumors in dogs and cats. Veterinary Medicine 2006.
Canine Liver and Anatomy from the canineliverfoundation.org