Primary liver, or hepatic, cancer is rare in dogs. Most commonly, a dog who develops a mass in the liver has a secondary (metastatic) cancer. Still, any liver tumor should be diagnosed and not ignored.
True liver cancer tends to grow slowly, but your dog can be uncomfortable and feel sick. Many metastatic cancers that settle in the liver, such as hemangiosarcoma, have shorter survival times and may be painful. Keep in mind your dog’s quality of life when making decisions about euthanasia due to liver cancer.
Many dogs will do well for months, or even years, despite having hepatic malignancy. You should be alert to changes such as the development of jaundice and lethargy. Loss of appetite and weakness can both signal that your dog is losing his battle with cancer.
Track his quality-of-life status. Is he eating? Can he still do the things he loves, like taking hikes in the woods or chasing his ball (even if you roll it for now)? Be prepared to schedule euthanasia for his sake, despite your pain.
Liver Cancer Symptoms
Common liver cancer symptoms in dogs are nonspecific with a few caveats. Many dogs will be “off.” They may seem nauseous, have a lack of appetite, and are lethargic or depressed.
Abdominal pain is often evident on palpation. Gastrointestinal upsets may occur. Some dogs will have weight loss but appear normal due to fluid buildup in the abdomen. Liver cancer can strike at any age but is mostly seen in older dogs.
If your dog becomes jaundiced, a liver problem jumps to the top of the list of possible reasons. Jaundice, or icterus, is associated with the destruction of red blood cells, liver disease, or gallbladder problems, particularly problems with the bile duct. With jaundice, you will notice a yellow discoloration to gums, the inside of ears, pale skin in the groin area, and in the sclera of the eyes.
Another sign pointing toward liver disease is neurological problems, which can range from zombie-like behavior to full-blown seizures.
Metastatic cancers in the liver tend to follow clinical signs of the primary cancer. For example, with hemangiosarcoma, your dog’s liver may be fragile, and he may suffer from periodic bleed outs, which can be fatal.
Types of Liver Cancer in Dogs
Hepatocellular adenocarcinoma: The most common type of primary liver cancer in dogs is hepatocellular adenocarcinoma. Hepatocelluar adenocarcinoma accounts for about 50% of all primary liver cancers in dogs. Male dogs are more prone to this type of liver cancer than females. If confined to one lobe of the liver and removed early on, this cancer can be controlled. Masses in the left lobe are easier for surgery.
Left to grow, the cancer cells may spread to other organs or cause bleeding into the abdomen. Liver failure is possible if the cancer grows unchecked as the tumor cells will overtake the normal liver cells and reduce liver function. If the mass has spread beyond one lobe, the prognosis is poor.
Hepatocellular adenoma: This is a benign version of hepatocellular adenocarcinoma. It is unlikely to spread, so surgical removal tends to be easier and can be curative. Despite being slow growing, it should be removed to proactively prevent rupture with a subsequent bleed out.
Bile-duct carcinoma: This is the second-most common primary liver cancer in dogs. Some might argue that these are gallbladder cancers, but many originate within the liver. Female dogs are more likely to get this form of hepatic cancer. Bile-duct carcinomas have a high rate of metastasis. They can also be tricky to totally remove surgically.
Hemangiosarcoma: The most common secondary or metastatic cancer in the liver is hemangiosarcoma. There are few options for treating hemangiosarcoma, and currently none of them are highly successful. The primary site, often the spleen or heart, would need to be treated as well. Plus, it’s important to consider the fact that it has already obviously spread to the liver, which means there is microscopic spread elsewhere. Palliative and hospice care is often your best option for this cancer.
Diagnosing Liver Cancer
A diagnosis of liver cancers usually involves a blood chemistry panel with elevated liver enzyme values and/or an ultrasound exam showing a liver mass. Special blood chemistry tests such as bile acids may be run.
Radiographs are not as helpful as an ultrasound exam. A biopsy is required for a definitive diagnosis. Since the liver is involved in most clotting pathways, care must be taken with any surgery on the liver, even a needle biopsy. A coagulation profile is routinely recommended before any invasive procedure.
Metastases Affect Treatment Options
Once the type of cancer is determined, treatment options will be discussed. A plus to the liver is that it has multiple lobes and amazing regenerative powers. If your dog’s cancer is confined to one area, surgery may be done to remove the tumor. Your dog can easily get along with a lobe, or even two, of his liver removed.
Before undertaking any surgery, your dog should be fully evaluated for metastases. This evaluation should include X-rays of the lungs. Histopathologic evaluation of nearby lymph nodes should be done, if possible.
The ideal treatment for liver cancer is surgery. However, if there has already been metastasis, surgery is not recommended. Chemotherapy has not been highly effective with liver cancer in dogs, but radiation, either before surgery to reduce the size of the mass, or post-surgery if there aren’t clear margins, can prolong survival.
Corticosteroids and palliative radiation can gain some quality time for your canine companion.
Supportive care is important. Liver supplements such as milk thistle may help the healthy liver tissues maintain normal functions. Keeping your dog in good physical shape is always a plus, which means appropriate exercise, other supplements for joint health and cognitive care, and a good diet.
Vaccinations
Currently, there is lots of research into immunotherapy and vaccines for various cancers. There is nothing definitive for liver cancer at this time, although hemangiosarcomas have stimulated lots of interest.
Preventing liver cancer, other than vaccinating for canine hepatitis (included in most multi-vaccines), is non-specific. Avoiding unnecessary exposures to toxins such as avoiding herbicide usage on your property can help.
As with any cancer, report any physical changes in your dog or unusual behavior immediately. Early detection and treatment remain our best weapons against liver cancer, or any cancer, for that matter.
