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A cancer diagnosis for your dog is heartbreaking and often overwhelming. It can be hard to take in all the information your veterinarian provides, and even harder to fully understand what a diagnosis of liver cancer means for your dog.

While your best source of information regarding any medical issue is always your veterinarian, here are some of the facts you need to know about liver cancer in dogs.

What Is Liver Cancer?

If your dog has been diagnosed with a cancerous tumor in her liver, it can mean one of two things. Either your dog has liver cancer, or your dog has another type of metastatic cancer that has spread to the liver.

Liver cancer is less common than metastatic cancer in dogs, but can and does occur. When it does, it is usually the result of hepatocellular carcinoma (HCC). HCC is the most common type of primary liver cancer (cancer that originates from the liver), but there are a few other types of liver cancer that can affect dogs, including bile duct carcinoma, neuroendocrine tumor, and mesenchymal tumor (sarcoma).

Hepatocellular Carcinoma

Hepatocellular carcinoma can present in three different ways. The tumor could be massive, which means the cancer is made up of a single large tumor and is not necessarily a description of tumor size; it could be nodular, which means there are several masses spread throughout the liver; or it could be diffuse, which involves the entire liver.

Luckily, most cases of HCC involve massive tumors. These have a lower rate of metastasis than nodular or diffuse tumors and are more easily removed, but without treatment, all the types of primary liver cancer can eventually metastasize to other parts of the body, such as the lymph nodes, lungs, and other organs.

Metastatic cancer of the liver, which means cancer that has spread from somewhere else to the liver, is usually associated with pancreatic cancer, lymphoma, intestinal carcinoma, thyroid cancer, fibrosarcoma, osteosarcoma, mast cell tumors, hemangiosarcoma, mammary carcinoma, pheochromocytoma, and transitional cell sarcoma.

What Dogs Get Liver Cancer?

Primary liver cancer usually affects older dogs, but that does not mean it can’t affect younger dogs. So far, experts have not noted any breed predispositions to primary liver cancers. However, dog breeds that are predisposed to other types of cancer that can metastasize to the liver, for example Golden Retrievers, a breed with a frequent occurrence of lymphoma and hemangiosarcoma, could potentially see liver involvement in their cancers.

Symptoms of Liver Cancer in Dogs

Unfortunately, many dogs with liver cancer are asymptomatic until the tumor reaches a large enough size to cause problems, which makes it a hard disease to prevent or catch early.

Once the cancer progresses, dogs may show some of the following symptoms:

  • Weight loss
  • Loss of appetite
  • Fever
  • Lethargy
  • Weakness
  • Polydipsia (excessive thirst)
  • Diarrhea

Some less common symptoms are vomiting and seizures, and some dogs may even have abdominal hemorrhaging from a necrotic tumor core.

Your veterinarian may be able to detect abnormalities in your dog’s liver at an exam. Liver enlargement or abdominal pain on palpation could point toward a liver problem such as liver cancer, and blood work can reveal liver abnormalities that also lead to a suspicion of cancer.

Diagnosing Liver Cancer in Dogs

Liver cancer is diagnosed using a multi-faceted approach. Your veterinarian may run laboratory tests to look for signs of liver dysfunction or damage. He or she may also take a urine sample, run some diagnostic imaging tests like radiographs and ultrasounds, and ultimately take a sample of the tumor by either a biopsy or a needle aspiration. These diagnostics are not without risk, and blood clotting tests are usually performed prior to needle aspirates or surgical biopsies.

These tests and samples allow veterinarians to diagnose what kind of cancer your dog has, and together you and your veterinarian will come up with the best treatment plan for your dog’s condition.

Treatment and Prognosis

Primary liver cancer in dogs sounds like a terrifying diagnosis, but the upshot is that the liver can regenerate, even if a large portion is removed. Also, massive HCC tumors grow slowly, giving your veterinarian the opportunity to remove the affected parts of your dog’s liver and greatly increasing her chances of a full recovery.

Surgical removal of the liver tumor is the preferred treatment for liver cancer and can be curative. Dogs that have had massive liver tumors removed have a good prognosis, and may live for years past the operation.

Some malignant tumors cannot be removed. Nodular or diffuse HCC tumors and tumors from a metastasized cancer, unfortunately, have a poor prognosis (usually allowing only 3-6 months). Chemotherapy can delay the progression of cancer, but will most likely not be curative, and your veterinarian will most likely discuss the options available for keeping your dog comfortable.

Your dog’s prognosis will depend upon a variety of factors, including the extent of the tissue involvement, the success of surgery and other treatment options, and your dog’s overall health. For the most accurate prognosis, consult your veterinarian.