Primary Liver Cancer in Cats and Dogs
What are liver tumors?
The liver is an organ consisting of several lobes that has a number of functions in the body, including metabolism,
glycogen storage, decomposition of red blood cells, plasma protein synthesis, and detoxification. Masses that develop
within the liver may be either benign (e.g. nodular hyperplasia) or malignant.  Liver tumors include hepatocellular
carcinoma (malignant), hepatocellular adenoma (benign) and hepatoblastoma (malignant). Liver tumors have been
reported to metastasize to other sites such as regional lymph nodes, lungs, kidneys, pancreas, spleen and others.

How common are liver tumors in cats and dogs?
Primary liver cancer is not common (<1.5% of all dog cancers and 1-2.9% of all cat cancers), however, the liver is a
common site to which cancers from other organs metastasize, particularly from the spleen, pancreas, and gastrointestinal
tract. Hepatoblastoma is a rare tumor, hepatocellular adenoma is more common in cats and hepatocellular carcinoma is
observed more frequently in the dogs.

What are the symptoms of liver tumors in cats and dogs?
Symptoms of liver tumors are often nonspecific, including lack of appetite, weight loss, lethargy, vomiting, increased thirst,
increased urination and accumulation of fluid in the peritoneal cavity. Uncommon symptoms may include
ataxia, weakness,
and seizures as a result of liver encephalopathy (a potentially life-threatening disease in which toxic substances
accumulate in the blood), or brain metastasis. Depending on which subtype of liver tumors is present, they may or may not
be felt during a physical examination.

How is the diagnosis made?
Blood and biochemical abnormalities are usually not specific, but elevation of the white blood cell count, deficiency of red
blood cells and presence of high platelet counts in the blood are common in dogs with liver tumors. Liver enzymes can be
elevated but are not specific to liver tumors.
Imaging techniques such as X-rays, ultrasound, CT and MRI are often
employed in evaluation of animals with suspected liver tumors. Ultrasound has been the preferred method but as CT and
MRI imaging becomes more widely available, these techniques will likely provide better information due to their high
sensitivity and resolution. Ultrasound-guided fine-needle aspiration or needle-core
biopsy of liver masses is a useful
diagnostic tools that are minimally invasive to obtain samples for histopathological analysis. These tools can obtain
diagnosis in up to 60% of liver aspirates and 90% needle-core biopsies. More invasive methods for obtaining tissue sample
is
laparoscopy.

Does cancer cause pain in pets?
Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the
actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or
chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery from the illness, treatment or
injury. It is, therefore, essential that veterinary teams that are taking care of pets with cancer should also play a vital role in
educating pet owners about recognizing and managing pain in their pets. The best way to manage cancer pain in pets is to
prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and
administers pain medication before the pet actually experiences pain, thus ensuring the pet's maximum comfort.

To learn more about which tumors are likely to cause a lot of pain, how to recognize pain in pets with cancer and what
cancer pain management options are available for your pet, please visit the
Cancer Pain Management section.

How important is nutritional support for pets with cancer?
Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets with cancer. Pets with
cancer lose weight partly because of lack of appetite and partly because of cancer-induced altered metabolism. Some of
the causes for decreased appetite are related to the cancer itself (for example, tumors may physically interfere with food
chewing, swallowing, and digestion process) and some may be related to the side effects of cancer treatment (for example,
some chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause mouth inflammation).

Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, improve survival times,
quality of life and maximize response to therapy. Adequate nutritional support was shown to decrease the duration of
hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pets with cancer need to
be fed diets specifically designed to provide maximum benefit and nutritional support for the patient. To learn more, please
visit the
Cancer Nutrition section.

What are the treatment options for liver tumors in cats and dogs?
Surgical treatment is recommended for cats and dogs diagnosed with primary liver tumors of massive morphologic
appearance, particularly hepatocellular carcinoma. Complications of this treatment include bleeding, transiently low
glucose levels and reduced liver function. There are not many treatment options for animals diagnosed with nodular and
diffuse hepatocellular carcinoma since multiple liver lobes are usually affected. The clinical utility of
radiation therapy and
chemotherapy has not been evaluated in animals, but human studies indicate that these treatments are largely ineffective.
A number of novel treatments are being evaluated in human clinical trials but such therapies have not yet entered the
veterinary oncology clinics.

How do I find a qualified veterinary oncologist?
To locate a qualified veterinary oncologist worldwide who can discuss with you appropriate cancer treatment plan for your
pet's cancer condition, please visit the "
Locate a veterinary oncologist" section.  

Are there any clinical trials investigating new treatments for liver tumors in cats and dogs?
There are no clinical trials specifically designed for liver tumors in pets, however, there are several clinical trials available
for cats and dogs with any tumor type for which your pet may qualify. To learn more these trials (which are partially or fully
funded by the institutions), please visit the
Dog Clinical Trials (any tumor type) or Cat Clinical Trials (any tumor type)
section.  

To learn more about veterinary clinical trials in general, please visit the
Pet Clinical Trials section.

What is the prognosis for cats and dogs with liver tumors?
The prognosis for pets with primary liver tumors is dependent on the histology and morphology of the tumors. The
prognosis for dogs with massive hepatocellular carcinoma treated by surgery is good. The prognosis for dogs with nodular
and diffuse hepatocellular carcinoma is poor since surgery is typically not possible due to the involvement of multiple liver
lobes rather than one.

Additional online resources about liver cancer in pets

Sources:
  • Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
  • Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins, 1998.
PET CANCER CENTER
Comprehensive guide to cancer diagnosis and treatment in cats and dogs
© 2007 Pet Cancer Center. ALL RIGHTS RESERVED.
Last updated 4/10/13
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