Liver Cancer in Dogs: Causes, Symptoms, Diagnosis, and Treatment
Liver cancer is a serious condition that can affect dogs of all ages and breeds. While it is not as common in dogs as it is in humans, liver cancer is still a significant concern for pet owners.
Early diagnosis and treatment are essential for managing the condition, and pet owners must be aware of the signs and symptoms to ensure their dogs receive prompt veterinary care.
In this article, we will provide an overview of liver cancer in dogs, including its causes, symptoms, diagnosis, treatment, home care, and prognosis. We will also address some common questions and concerns that pet owners have about liver cancer in dogs, such as the lifespan of dogs with liver cancer and the pain associated with the condition.
What is Liver Cancer in Dogs?
Most people have a general idea of what cancer is, but I want to review a precise description of the disease.
Cancer is a disease caused by the uncontrolled growth of abnormal cells in an animal. Normal cells of the body have mechanisms that shut off their growth when there are just enough of them but not too many. When abnormal cells overgrow, they cause inflammation, organ failure and loss of nutrients. Advanced stages of cancer affect the whole body and may lead to the death of the animal.
Tumors of the liver can be primary in nature, meaning they started in the liver. The two most common primary types of liver tumors are liver cell tumors and bile system tumors. Primary liver tumors are relatively uncommon in dogs.
Hepatocellular carcinomas are the most common type of primary hepatic tumor in dogs. These tumors develop from the cells that make up the liver itself, and they can grow in any part of the liver.
Primary cholangiocellular tumors, on the other hand, develop from the cells that line the bile ducts within the liver. These tumors can cause bile to accumulate in the liver, leading to liver damage and dysfunction.
The liver is also a common site for secondary tumors. These are metastatic tumors that have spread to the liver from other parts of the body, such as the spleen, pancreas, kidneys or intestines. Secondary tumors are more common than primary liver tumors in dogs. In many cases, secondary tumors in the liver are an indication of advanced cancer in another part of the body.
Understanding the different types of liver tumors that can affect dogs is essential for accurate diagnosis and treatment.
How Common Is It and What Causes It?
Primary liver cancer is uncommon in dogs with only about 1.5% of all dogs being affected. Secondary or metastatic liver cancer is much more common with more than 30% of cancers spreading to the liver by way of blood. (2)
There is no dog breed recognized as high risk for the disease, but dogs over the age of about 11 years have a higher risk of getting some type of liver cancer.
Researchers have yet to determine the specific causes of canine liver cancer. You may find reports that mold toxins in dog food cause liver cancer but experts agree it’s not as common in dogs as it is in humans.
Symptoms
Many dogs show few symptoms of liver cancer until it is in an advanced state. Early signs include finicky appetite, vomiting, diarrhea and lethargy.
Once liver cancer has affected a significant portion of the organ, dogs display more obvious symptoms. These might include a swollen belly, panting, refusal of food plus increased drinking and urination.
Some dogs develop jaundice which is caused by disruption of normal bile metabolism in the liver and/or gallbladder. Easy places to detect jaundice are the whites of the eyes and gum tissue in the mouth. Dogs with excessive bilirubin in their blood usually have orangish poop and yellow-orange urine.
During end-stage liver disease, a dog’s liver fails to clean the blood normally, allowing toxins to build up. Hepatic encephalopathy (HE) occurs when blood toxins like ammonia are very elevated. Dogs with HE have more extreme symptoms such as seizures, weakness and collapse.
Dog owners often ask if their dog is in pain from liver cancer. It’s hard to answer the question without being a dog mind reader, but my interpretation is that if a dog doesn’t want to eat and has any of the symptoms listed above, they do have some degree of pain.
Diagnosis
Very early liver cancer often goes unnoticed as it doesn’t cause a lot of symptoms. It takes more diagnostic tests to find early-stage cancer. Late-stage liver cancer is often large enough to cause changes on plain radiographs and standard blood tests. But since liver nodules can be non-cancerous, testing is essential.
Testing a dog for liver cancer often includes:
- Complete blood count, blood chemistry panel, electrolyte levels
- Urinalysis
- Bile acids tests for liver function
- Blood clotting profiles
- Radiographs
- Ultrasound imaging
- Biopsy or cytology of affected tissue
Veterinarians sometimes collect samples of the liver either by using an ultrasound-guided needle or biopsy collector without putting the dog under anesthesia. Some dogs need a surgical exploratory procedure to diagnose liver lesions.
Treatment
The preferred treatment for liver cancer is surgical removal of the entire mass. That’s not always possible when the tumor is large or has spread to other organs.
Chemotherapy is used after surgical resection to destroy microscopic cancer cells that may have been left behind. Dogs with tumors that can’t be removed surgically may also benefit from chemotherapy if they have mast cell cancer, hemangiosarcoma or lymphoma-type tumors.
Radiation therapy is not used much to treat liver cancer in dogs. Radiation causes too much damage to the healthy liver tissue to be helpful.
Home Care Tips
No matter which type of liver cancer your dog has, the most important thing you can do to help them is to work with your veterinarian. Through careful observation, you and your vet can tailor the treatment to keep your dog comfortable.
A couple of the common issues dogs with liver cancer face are poor appetite and nausea. Your vet may want to prescribe anti-nausea medication, appetite stimulants and a special diet such as Hills l/d® or n/d® diet for dogs. Some dogs may also benefit from supplements such as milk thistle and S-Adenosylmethionine (SAM-e). Ask your vet for advice before giving any over-the-counter supplements!
You need to stay flexible when dealing with canine liver cancer. Your dog may be full of energy one day but sleepy and lethargic the next. Do what you can to keep their spirits up without overdoing exercise or treats. I find some dogs don’t feel well enough to go for a walk but still appreciate a short ride in the car to sit quietly in a park.
How to decide when to euthanize a dog with liver disease…
What Is the Life Expectancy for a Dog with Liver Cancer?
The life expectancy for a dog with liver cancer depends on the tumor type and size. Primary hepatocellular carcinoma in a single liver lobe with a tumor size of 5.0 cm or smaller has the best prognosis with proper treatment. (2)
The three types of liver tumor locations are
- Massive–tumors affecting only one lobe of the liver. Longest life expectancy, 4 years or more with surgery and chemotherapy.
- Nodular–tumors in multiple liver lobes. Life expectancy depends on treatment. Maybe up to 6 months with surgery and chemotherapy.
- Diffuse–tumors invade tissue throughout the liver. Shortest life expectancy of days to a few months.
One study found dogs who had surgery for hepatocellular carcinoma had a life expectancy of around 4 years. Dogs who did not have surgery had a median survival time of about 9 months. (1)
Biliary tumors tend to be of the nodular or diffuse type and have a poorer prognosis. Even when part of the liver is surgically removed, this type of liver tumor tends to recur and lead to the dog’s death within 6 months.
Secondary liver cancer is often of the diffuse type. It’s not possible to remove diffuse cancer from the liver surgically, so chemotherapy is the treatment of choice. The survival time for dogs with metastatic liver cancer depends on the primary tumor type. In dogs who had primary mammary cancer that spread to their liver, the median survival time was 3-24 months in one report.
Key Points
- Liver cancer in dogs is caused by the uncontrolled growth of abnormal cells in the liver and can be of a primary or secondary nature.
- Early diagnosis and treatment are essential for managing liver cancer in dogs. The symptoms of liver cancer in dogs can be subtle and may include vomiting, diarrhea, and lethargy.
- Diagnostic tests for liver cancer in dogs include a complete blood count, blood chemistry panel, electrolyte levels, urinalysis, bile acids tests, radiographs, ultrasound imaging, and biopsy.
- The preferred treatment of liver cancer in dogs is surgical removal, especially if it’s a solitary mass. Chemotherapy is used after surgery to destroy microscopic cancer cells that may have been left behind. Radiation therapy is not used much to treat liver cancer in dogs.
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References
- Liptak, J. M., Dernell, W. S., Monnet, E., Powers, B. E., Bachand, A. M., Kenney, J. G., & Withrow, S. J. (2004). Massive hepatocellular carcinoma in dogs: 48 cases (1992–2002). Journal of the American Veterinary Medical Association, 225(8), 1225-1230.
- Vilkovyskiy, I. F., Vatnikov, Y. A., Kulikov, E. V., Sotnikova, E. D., Yagnikov, S. A., Seleznev, S. B., … & Avdotin, V. P. (2020). Influence of hepatic neoplasia on life expectancy in dogs. Veterinary World, 13(3), 413.