Vet-Approved: Liver Cancer in Dogs – What It Is and How to Treat It

Liver cancer can be benign or malignant and arises from various forms and risk factors, with malignant types often spreading to other organs.

This article explains everything about liver cancer in dogs, how it differs from liver tumors, and covers signs, diagnosis, treatment, and life expectancy.

What is Canine Liver Cancer?

Liver cancer is an oncological disease characterized by the presence of one or more tumors (growths) in the liver. These can either involve benign liver tumors or malignant liver tumors. This condition usually occurs in older dogs.

Malignant tumors are cancerous in nature. In liver cancer, hepatocytes multiply uncontrollably, and lose their function, damaging healthy cells and disrupting liver structure.

Liver cancer can be primary, originating in liver cells, or secondary (metastatic), spreading to the liver from other organs. The liver is a common site for metastasis of cancerous cells like in the case of osteosarcoma and intestinal carcinoma.

This serious disease can also be hemolymphatic, originating from blood cells or the lymphatic system.

Primary Liver Cancer in Dogs

In dogs, primary liver cancer is rare, arising within various liver cell types, while metastatic liver cancer is more common. It represents approximately 1% of all cancers in dogs.

The most common primary liver cancers in dogs include:

• Hepatocellular carcinoma: Originates from hepatocytes.
  
• Bile duct carcinoma: Develops from bile duct tumors.
  
• Neuroendocrine tumors (carcinoid): Arise from hormone-secreting cells.
  
• Mesenchymal tumors (sarcomas): Form in the liver's connective tissue.
  

Primary liver tumors can spread to other parts of the liver and organs like lymph nodes, lungs, and abdominal organs. Neuroendocrine tumors, bile duct carcinomas, and certain hepatocellular carcinomas are most likely to metastasize.

Hepatocellular carcinoma in dogs 

Hepatocellular carcinoma, affecting liver cells, is the most common primary liver cancer in both dogs and humans.

Hepatocellular carcinoma (HCC) occurs in three forms:

• Solitary (massive) HCC: Found in a single liver lobe ( 50-80% of cases).
  
• Nodular HCC: Affects multiple lobes, giving the liver a nodular appearance (16-25% of cases).
  
• Diffuse HCC: Spreads throughout the entire liver (19% of cases).
  

Nodular and diffuse hepatocellular carcinoma have the highest metastasis rates, at 90-100%.

The prognosis for dogs with hepatocellular carcinoma varies by type. Massive HCC has a better outlook, with a mean survival time of over 1,460 days after complete surgical resection and 270 days without surgery. Nodular and diffuse forms have a poorer prognosis.

Carcinoma of the bile ducts in dogs

Bile duct carcinoma (cholangiocarcinoma) is the second most common liver cancer in dogs and the most common in cats. It originates in the bile ducts, which connect the liver and gallbladder to the intestine to transport bile.

Dogs have extrahepatic (outside the liver) and intrahepatic (inside the liver) bile ducts, with cholangiocarcinoma more commonly affecting the intrahepatic ducts.

Bile duct cancer is rare but aggressive in dogs, generally carrying a poor prognosis. However, dogs with intrahepatic cholangiocarcinoma have a better outlook, with a median survival time of 492 days after complete surgical resection.

Tumors of neuroendocrine origin (carcinoid) in dogs

Neuroendocrine tumors (carcinoids) in dogs are rare. These tumors arise from neuroendocrine cells, which share traits with both nerve and hormone-producing cells. Neuroendocrine cells regulate physiological and metabolic activities by releasing hormones into the bloodstream.

Carcinoids can develop in various parts of the body, including the stomach, intestines, pancreas, esophagus, skin, adrenal glands, lungs, thyroid, liver, and heart. They may appear as nodular or diffuse tumors.

Carcinoids have a guarded prognosis, with frequent metastasis.

Mesenchymal tumors (sarcomas)

Primary liver sarcomas are rare in dogs, with leiomyosarcoma being the most common, originating in smooth muscle fibers. Other types include:

• Fibrosarcoma: Arises from connective tissue cells.
  
• Hemangiosarcoma: Develops in the vascular endothelium.
  
• Rhabdomyosarcoma: Originates in striated muscle fibers.
  
• Osteosarcoma: Forms in bone cells (primary liver osteosarcoma is extremely rare, even in humans).
  
• Liposarcoma: Arises from fat cells.
  

Hepatic sarcomas are highly aggressive with a poor prognosis, showing an 86-100% metastasis rate. They often spread to the spleen, lungs, or diffusely within the liver.

Benign Liver Cancer in Canines

Not all canine liver cancers are malignant; some are benign (non-cancerous) tumors, including:

• Hepatocellular adenoma
  
• Bile duct adenoma
  
• Hemangioma
  
• Leiomyoma
  

These tumors tend to grow slowly and are the most commonly diagnosed in dogs.

Benign tumors have a good prognosis and are treated with surgical removal. They don’t spread or cause issues unless they grow large, affect other organs, or rupture and bleed, potentially causing complications.

Secondary or Metastatic Canine Liver Cancer

Most metastatic liver cancers arise from the spleen, pancreas, or intestinal tract but can also spread from any other parts of the dog’s body. This type of liver cancer is 2.5 times more common than primary liver cancer.

The most common cancers that spread to the liver include:

• Lymphoma: Cancer of the lymph nodes and lymphatic system; occasionally primary liver cancer.
  
• Pancreatic cancer: Rare and severe, with insulinoma and pancreatic adenocarcinoma as common types.
  
• Intestinal adenocarcinoma and carcinoid: Rare cancers, with carcinoids more likely to spread to the liver.
  
• Thyroid cancer: Thyroid carcinoma often metastasizes to the lungs but can also affect the liver, heart, bone, or brain.
  
• Osteosarcoma: The most common bone cancer in dogs; aggressively spreads to lungs, liver, spleen, and lymph nodes. Rarely a primary liver cancer.
  
• Mast cell tumor (MCT): Aggressive skin cancer that frequently spreads to the liver (sometimes even in multiple liver lobes), spleen, and lymph nodes.
  
• Transitional cell carcinoma (TCC): Urinary tract cancer that metastasizes to the lungs, liver, and lymph nodes, with lymph nodes being the most common.
  
• Mammary carcinoma: The most common breast cancer in intact females, aggressively spreading to the lungs, liver, heart, bones, and lymph nodes; often resistant to treatment.
  
• Hemangiosarcoma: Malignant cancer of blood vessels, often affecting the spleen, heart, lungs, and liver. Occasionally a primary liver cancer.
  

How Do Dogs Get Liver Cancer?

The exact causes of liver cancer in dogs are unclear, but several factors increase their risk, including:

Genetic predisposition

Certain dog breeds are more prone to liver cancer, including Rottweilers (lymphoma, hepatocellular carcinoma), Weimaraners (mast cell tumors), Golden Retrievers (mast cell tumors, hepatocellular carcinoma), German Shepherds, Welsh Corgis, Beagles, and Poodles (hepatocellular carcinoma). Males are more likely to develop hepatocellular carcinoma, while females are prone to bile duct carcinoma.

Age 

Liver cancer usually occurs in dogs over 9 years of age.

Chronic liver disease

Chronic liver disease, as in humans, can increase the risk of liver cancer in dogs.

Carcinogens

Long-term exposure to chemicals, secondhand smoke, and aflatoxins increases the risk of liver cancer in dogs.

• Can dog food cause liver cancer? Yes, small amounts of aflatoxins have been found in many dog food brands. Prolonged consumption of contaminated food can lead to cancer or death.
  
• What foods cause liver damage in dogs? High-carb diets over time can contribute to liver dysfunction. Additionally, toxic human foods like grapes, raisins, and xylitol (artificial sweetener) can cause severe liver damage.
  

Hormonal imbalances

Hormonal imbalances and endocrine disorders, such as Cushing's disease, can contribute to liver cancer in dogs. Excessive exposure to adrenocortical hormones can cause steroid hepatopathy, which may progress to hepatocellular carcinoma. Studies also show hyperadrenocorticism (Cushing's disease) is commonly associated with hepatocellular carcinoma.

Metastasis of other cancers that spread at a distance

As noted, canine liver cancer can also be secondary, originating from other cancers that spread.

• How quickly does liver cancer progress in dogs? Progression depends on the cancer type. Massive hepatocellular carcinoma progresses slowly, while untreated malignant (metastatic) cancers can grow and spread to other organs within months.
  

What are the Clinical Signs of Liver Cancer in Canines?

Clinical signs of canine liver cancer vary by type and stage, appearing gradually or suddenly. Common signs include:

• Loss of appetite and weight loss: Caused by nausea or abdominal pain, leading to noticeable weight loss.
  
• Lethargy: Reduced energy, excessive sleeping, or disinterest in daily activities.
  
• Weakness: Difficulty climbing stairs or walking due to muscle loss, anemia, or toxin buildup.
  
• Nausea and vomiting: Indicated by frequent lip licking and vomiting undigested food, bile, or liquids.
  
• Diarrhea: Persistent loose or bloody stools.
  
• Abdominal pain: Enlarged, painful liver causing crying, hunching, or avoiding abdominal contact.
  
• Jaundice: Yellowing of skin, eyes, or gums due to bilirubin buildup.
  
• Excessive thirst (polydipsia): Increased water consumption to combat dehydration or dilute toxins.
  
• Excessive urination (polyuria): Often linked to increased water intake or kidney damage.
  
• Distended abdomen (ascites): Fluid buildup in the abdominal cavity from impaired circulation.
  
• Anemia: Pale gums, weakness, and decreased red blood cells due to spleen enlargement or tumor rupture.
  
• Prolonged bleeding or bruising: Clotting issues from liver dysfunction causing bruises, petechiae, or prolonged bleeding.
  

Early signs of liver cancer, often subtle and easily mistaken for minor conditions, include reduced appetite, mild weight loss, slight lethargy, intermittent vomiting, occasional diarrhea, and mild abdominal discomfort.

Seek veterinary care immediately if these signs are observed.

What are the Final Stages of Dog Liver Cancer?

In the final stages of liver cancer, the disease often progresses to a point where it significantly reduces a dog’s quality of life. This decline occurs as the liver fails to perform its essential functions due to extensive tumor growth and metastasis, leading to severe and debilitating symptoms.

The final stages of canine liver cancer can include:

• Loss of appetite and severe weight loss
  
• Severe weakness
  
• Persistent vomiting and diarrhea
  
• Jaundice
  
• Ascites (fluid accumulation in the abdomen)
  
• Breathing difficulties, often caused by lung metastases
  
• Neurological symptoms due to hepatic encephalopathy, such as seizures, disorientation, or behavioral changes
  
• Significant abdominal pain, causing reluctance to move or restlessness
  

Malignant Liver Tumors and Cancer in Canines: When to Euthanize?

When there is uncontrollable physical pain, inoperable liver masses, severe weight loss, respiratory problems, and a continuing decline in your dog's quality of life, it is time to consider ending their suffering: humane euthanasia.

How Veterinarians Diagnose Liver Cancer in Dogs

If your dog shows the clinical signs mentioned above, a veterinarian can diagnose liver cancer through a series of examinations and tests, such as:

• Physical examination: During the physical examination, the veterinarian may detect a mass, fluid in the abdomen, or an enlarged liver. These findings are often accompanied by abdominal pain.
  
• Blood tests: A complete blood count (CBC) can detect anemia, particularly in cases of tumor rupture. Blood biochemistry can reveal changes in liver enzyme levels, indicating liver dysfunction.
  
• Bile acids testing: This test evaluates liver function by measuring the ability to process bile acids. Elevated levels may indicate liver dysfunction, including the possibility of liver cancer in dogs.
  
• Coagulation tests: A diseased liver can impair blood clotting in dogs. These tests assess the dog’s ability to form blood clots, which is critical for diagnosing and managing clotting disorders.
  
• Alpha-fetoprotein (AFP): This protein is synthesized during fetal development in the liver, gastrointestinal tract, and yolk sac. Elevated AFP levels are associated with hepatocellular cancer, making this test a valuable diagnostic tool for liver cancer in dogs.
  
• Urine tests: The presence of bilirubin in the urine can be an early sign of liver cancer.
  
• Abdominal ultrasound: This diagnostic tool allows the veterinarian to observe structural changes in the liver and identify tumors, whether they are massive, nodular, or diffuse. The ultrasound can also determine whether the cancer affects one or multiple liver lobes and detect bile duct or gallbladder obstruction.
  
• X-rays: Abdominal and thoracic X-rays can help visualize tumors, including their location, shape, and size, especially if an ultrasound has not been performed. X-rays are also useful for detecting metastases in other organs, such as the lungs, which is particularly important in advanced stages of the disease.
  
• CT scans or MRI: These imaging tests help to locate the tumor and assess the tumor size and shape.
  
• Ultrasound-guided fine needle aspiration (FNA): When one or more masses are found in the liver, your vet will recommend ultrasound-guided FNA to obtain a sample of cells that will be further examined under a microscope for the diagnosis of liver cancer (cytological exam).
  
• Biopsy: If the results of the cytological examination are inconclusive, the veterinarian may recommend a biopsy. This procedure involves using a long, hollow needle to extract a small tissue sample from the tumor through the skin. The sample is then analyzed under a microscope by a pathologist to provide a definitive diagnosis.
  

Immediate and definitive diagnosis is necessary to begin treatment because many forms of liver cancer are aggressive and can metastasize to other organs.

What is the Treatment for Liver Cancer in Dogs?

For treating liver cancer in dogs, several options are available, including surgery, chemotherapy, and stereotactic body radiation therapy. The choice of treatment depends on factors such as the type, size, and location of the tumor, as well as the overall health of the dog.

Surgical removal of malignant tumors and cancer

Surgery is often the preferred treatment for primary liver cancers in dogs, as tumors confined to a single liver lobe are easier to remove. However, surgery is not an option for secondary liver cancers, as the presence of cancer in the liver typically indicates that the disease has already spread throughout the body.

An encouraging aspect of liver surgery is the organ's ability to regenerate. Dogs that have a portion of their liver removed can often regain normal liver function over time.

Stereotactic Body Radiation Therapy (SBRT)

When a liver tumor is inoperable, stereotactic body radiation therapy (SBRT) can be considered as a treatment option. This advanced radiotherapy technique, often used for hepatocellular carcinoma in humans, delivers high doses of radiation with extreme precision. It targets small tumors in one or a few sessions, destroying neoplastic cells through necrosis while minimizing damage to surrounding healthy tissues.

Because of its targeted approach, SBRT offers a promising alternative for cases where surgery is not possible. However, some dogs may experience hepatic and renal side effects. These potential adverse reactions should be discussed with the veterinarian to determine appropriate management strategies.

Chemotherapy

Chemotherapy is recommended by veterinarians for both primary and secondary liver tumors. Chemotherapy may be administered after the tumor has been removed by surgical resection, along with radiation therapy, or if the tumor(s) cannot be removed surgically.

Are There Any Alternative Treatments for Liver Cancer in Dogs?

If your dog has liver cancer, some homeopathic products may help strengthen their immune system and complement conventional treatments as a gentler approach.

While homeopathic treatments do not cure or replace conventional cancer therapies, they will help support your dog's body, strengthen the immune system, and help prolong their life.

PIPTOPET is designed to support your dog during liver tumors and cancer

One product that may strengthen your dog's immune system and support their fight against cancer is PIPTOPET. This supplement contains Fomitopsis betulina, a mushroom renowned for its health benefits. Studies on dogs, monkeys, and mice have demonstrated its anti-inflammatory, antiviral, antibacterial, antioxidant, and anticancer properties.

PIPTOPET is part of the Optimal Kit, which includes additional TONICPET products designed to complement its properties. The kit contains:

TONICPET #4: Supports the immune system and promotes healthy oxygen circulation throughout the body.

TONICPET #5: Enhances circulation and overall bodily function.

TONICPET #7: Boosts the immune response and improves oxygen circulation in deeper skin layers.

TONICPET #10: Helps balance acidity levels and supports digestive health. By creating a less acidic environment, it discourages tumor growth, as cancer cells thrive in acidic conditions.

Combining these products provides your dog with a natural, powerful boost to their immune system and overall health.

Other natural support products you should consider

CBD oil (cannabidiol) is a natural product that may help your cat fight lymphoma by stimulating programmed cell death (apoptosis) in cancer cells and reducing their viability.

S-adenosyl-methionine (SAMe) is a supplement that supports liver function recovery and, according to studies, selectively inhibits the growth and invasiveness of liver cancer cells.

Milk thistle, a centuries-old liver tonic, can help dogs with liver cancer by supporting liver recovery and protecting its functions. You can also consult a professional pet homeopath to explore additional treatment options.

About the author

Dr. Iuliana Mihai, DVM, MSc, PhD

Iuliana Mihai, DVM, MSc, PhD, is a Bucharest-based veterinary expert specializing in internal medicine and oncology.

Her work has been published in reputable publications such as Veterinary Medicine Journal, Catster.com, Dogster.com, Hepper.com, Meowiz.com, Springnaturals.com, Petkeen.com, and Wilderharrier.com.

She is a malpractice and negligence veterinary consultant and a graduate of The University of Agronomic Sciences and Veterinary Medicine and The Romanian Academy.

Read the complete profile of Dr. Iuliana Mihai, DVM, MSc, PhD (Veterinarian) here.