Liver cancer in dogs is a diagnosis no dog parent wants to receive. Yet a variety of cancers can, and sometimes do, affect a dog’s liver. To help you navigate your dog’s liver cancer diagnosis, integrative veterinarian Dr. Julie Buzby explains the types, symptoms, diagnosis, treatment, and prognosis for liver cancer in dogs.
If your veterinarian just said the words “liver cancer,” it may feel like your world is crashing down around you. No one wants to hear that their beloved dog has cancer. And liver cancer is no exception.
While your veterinarian probably discussed your dog’s situation with you and laid out the options for the next steps, I know it can be hard to absorb information when you are still reeling from receiving bad news. And I want to help support you in your time of need. That’s why I created this guide to liver cancer in dogs.
What is liver cancer in dogs?
As you probably already know, cancer occurs when abnormal (i.e. cancerous) cells in the body start multiplying out of control. They can invade tissues or organs and spread to other parts of the body.
In the case of liver cancer, sometimes the abnormal cells originate from the liver itself (i.e. primary liver cancer). And in other situations, the cancerous cells may spread to the liver from a tumor elsewhere in the body (i.e. secondary liver cancer).
What are the types of liver cancer?
In addition to classifying the tumor as primary or secondary, veterinarians also group liver tumors based on their distribution in the liver and the cells they originated from.
Liver tumors come in three forms:
- Massive—single large tumor in one lobe of the liver
- Nodular—several masses spread throughout the liver lobes
- Diffuse—tumor cells distributed throughout the liver tissue
Additionally, primary liver tumors fall into four categories based on what cell type they arose from:
- Hepatocellular—originating from liver cells
- Cholangiocellular— growing from the cells of the biliary duct
- Mesenchymal— arising from cells that become muscle, connective tissue, fat, and blood vessels
- Neuroendocrine—originating from nervous system cells that can create hormones
The vast majority (75%) of primary liver cancers in dogs are hepatocellular. Mesenchymal is next at 11%, followed by cholangiocellular at 9% and then neuroendocrine at 3%.
Finally, and perhaps more importantly for your dog, liver tumors are classified as either being benign or malignant. Benign tumors remain in one location and don’t usually cause much trouble for the dog. On the other hand, malignant (i.e. cancerous) tumors can spread to other locations and cause more damage to the tissue.
There are a number of different liver tumors, but let’s take a look at a few of the most common.
Which liver tumors are cancerous?
Unfortunately, dogs may develop malignant liver tumors. Some of the more common types include:
Hepatocellular carcinoma (HCC) is most common type of primary malignant liver tumor in dogs, and also the most common hepatocellular tumor. It is often a solitary lesion, which is good news because that makes it easier to remove surgically. Single tumors also have a low rate of metastasis.
However, diffuse and nodular forms are also possible, and have a higher metastatic rate. HCC occurs more often in males than females, and the Welsh Corgi may be predisposed to it.
Cholangiocellular (biliary) carcinoma
The second most common type of primary liver cancer in dogs is cholangiocellular carcinoma. Compared to HCC, cholangiocellular carcinoma most commonly has a diffuse distribution and carries an increased risk of metastasis. It is more likely to occur in females than in males.
Hemangiosarcoma in dogs is a mesenchymal type of liver cancer that can be primary or secondary and tends to spread very quickly. HSA is prone to rupturing suddenly, which often leads to life-threatening bleeds that originate from the liver. Labrador Retrievers, Golden Retrievers, and German Shepherd Dogs may be more likely to develop this kind of cancer.
Lymphoma in dogs is another mesenchymal tumor which can either be primary or secondary. Most often, it starts in the lymph nodes and then spreads to other parts of the body like the spleen, lungs, and liver. However, it is also possible for lymphoma to originate from the liver.
Secondary (metastatic) tumors
Up to this point we have talked about primary liver cancers or ones that can be primary or secondary. However, the liver is also a common location for metastasis (i.e. spread) of other types of cancer. In fact, one study indicated that only 26% of liver masses were primary. This means the vast majority of the time, a dog’s liver mass is the result of cancer spread from another location.
Some common types of secondary liver cancer include:
- Exocrine pancreatic carcinoma
- Intestinal carcinoma
- Islet cell carcinoma
- Renal carcinoma
- Mast cell tumors in dogs
Which liver tumors are benign?
However, not all liver tumors are malignant. Dogs can also develop benign tumors such as:
As the name indicates, hepatocellular adenomas arise from the liver cells (i.e. hepatocellular origin) and are usually solitary tumors. Some hepatocellular adenomas can grow quite large. They are often an incidental finding on imaging like ultrasound, and symptoms may only appear if the mass starts to bleed or presses on surrounding internal organs.
These bile duct (i.e. cholangiocellular) tumors are also solitary and sometimes lobulated. Like with hepatocellular adenoma, dogs can be asymptomatic at first.
Myelolipomas are single mesenchymal tumors that can originate from the liver or other internal organs within the abdomen. They occur more often in cats than dogs, and are usually an incidental finding on imaging.
Hepatic nodular hyperplasia
Nodular hyperplasia is a benign process in which multiple nodules form in the liver lobes of older dogs. These nodules are not a precursor to cancer, do not alter liver function, and are typically asymptomatic.
What are the symptoms of liver cancer?
With most liver tumors, the signs are often vague or non-existent. In fact, one in four dogs with liver cancer are asymptomatic. And many times the vet doesn’t diagnose the dog with liver cancer until he or she happens to palpate an enlarged liver during a physical exam or find the tumor on imaging (e.g. X-rays or ultrasound). This is one of many reasons why annual or semi-annual exams are important—they may be responsible for a diagnosis of liver cancer before it causes symptoms!
If the dog is symptomatic, he or she may show signs such as:
- Weight loss
- Poor appetite
- Increased thirst in dogs and increased urination
- Being a lethargic dog
In more advanced cases, the dog may develop ascites (i.e. free fluid in the abdomen). The fluid can give a pot-bellied dog appearance and push on the diaphragm, making it harder for the dog to breathe. Additionally, some dogs develop low blood sugar as a result of the liver tumor (i.e. paraneoplastic hypoglycemia). This may cause the dog to be weak. collapse, or have seizures in dogs.
Dogs with hemangiosarcoma of the liver and/or spleen may also experience sudden and life-threatening internal bleeding if the tumor ruptures. This can lead to collapse, pale gums, weakness, and even death. This is a situation where time is of the essence, so if you notice any of those signs, make an emergency vet visit immediately.
How is liver cancer diagnosed in dogs?
With the exception of sudden internal bleeding, many of these symptoms of liver cancer are vague and could point to many different conditions such as diabetes in dogs, Cushing’s disease in dogs, liver disease in dogs, or kidney failure in dogs. This means that your veterinarian may need to perform a variety of tests to determine that it is liver cancer—and not another condition—causing the signs.
Alternatively, other dogs may have no outward sign that anything is wrong with them. It isn’t until the mass ruptures or the vet does a wellness exam and bloodwork that liver cancer comes up as a possibility.
Either way, the vet may perform some of the following diagnostics:
The vet may recommend bloodwork as part of the wellness visit or to start tracking down the cause of vague symptoms. Typically this involves a complete blood count (CBC) and chemistry panel, but the vet may add on other tests like a clotting profile.
If the vet palpates an enlarged liver or the bloodwork points to a liver problem, sometimes he or she may take an abdominal X-ray to evaluate the size and shape of the liver. But it isn’t usually possible to definitively find a liver tumor on X-rays. Advanced imaging like ultrasound, MRI, or CT are much more sensitive for detecting liver cancer.
X-rays are however, very good at looking for evidence of metastasis to the lungs or enlargement of other organs like the spleen. So the vet may recommend them as a staging tool after finding a liver tumor.
Ultrasound, CT, or MRI
The best ways to find and evaluate liver tumors are abdominal ultrasound, CT, or MRI. These advanced imaging modalities allow the vet to look in and around the liver lobes and get an idea of what the liver tissue looks like. Plus, the vet can use the ultrasound or other advanced imaging to assess the rest of the internal organs (such as the spleen, since splenic masses in dogs may spread to the liver).
Fine needle aspirate (FNA)
After identifying a liver mass, the vet may perform a fine needle aspirate or FNA. This involves using a needle to collect cells from the mass to determine what kind of tumor it is and if it is benign or malignant. However, it is important to know that an FNA can only correctly diagnose a liver tumor 60% of the time.
Performing a biopsy to remove a portion of the tumor correctly characterizes a liver tumor 90% of the time, making it superior to FNA for tumor identification. However, it is a much more invasive test and comes with a higher risk of bleeding, especially if the tumor is fragile.
What is the treatment for liver cancer in dogs?
Once your vet diagnoses your dog with liver cancer, he or she will discuss the treatment options with you. The type of tumor, location, distribution, and overall status of your dog’s health will all factor into these decisions. Some possible options include:
Surgery for liver cancer
Surgical removal of the tumor is the treatment of choice, but it isn’t possible for all tumors. A veterinary surgeon can usually remove a solitary mass, or cancer that is localized to one liver lobe or the gallbladder. This is the case because the liver is comprised of several lobes. A liver lobectomy (i.e. removing a lobe) may not impact overall liver function. Plus, the liver has regenerative properties and can even function when up to 75% of it is removed!
However, if the dog has secondary liver tumors (i.e. ones that spread to the liver from a different site), the cancer is diffuse, or the primary tumor has already metastasized, surgery is typically not a good option.
Depending on the type of liver cancer and how the surgery went, the veterinary oncologist may recommend chemotherapy after the tumor removal. Plus, chemotherapy is sometimes an option for nodular or diffuse liver cancers where surgery isn’t possible. When used for primary liver tumors, it may delay progression in some cases. And chemotherapy is an important part of treatment for lymphoma, mast cell tumors, and hemangiosarcoma.
Additionally, there is a newer procedure called chemoembolization. It involves using a catheter to deliver chemotherapy and an agent to block blood flow directly to a blood vessel feeding the tumor. This cuts off the blood supply to the tumor and delivers the chemotherapeutic agent directly to the tumor cells. While it seems promising, chemoembolization is not yet widely available and its benefits are not fully known at this point.
The liver is very sensitive to the effects of radiation, so for the most part it isn’t a good option for dogs with liver cancer. However, some veterinary oncologists are using stereotactic (i.e. precisely targeted) radiation for dogs with liver cancer.
Natural treatments for liver cancer
Like with most cancers, it is very unlikely that natural and holistic therapies will cure liver cancer in dogs. However, some holistic and natural treatments are available that may help support dogs with liver cancer.
- Supplements containing milk thistle have a protective effect on the liver because of milk thistle’s anti-inflammatory and antioxidant properties.
- Curcumin, which is found in turmeric, is also an anti-inflammatory and has been shown to kill cancer cells in a laboratory setting.
- An herbal supplement called dispel stasis in the middle palace can be used to help with blood stasis (i.e. slowing of blood flow through the liver) and liver qi stagnation (which causes abdominal pain and poor digestion).
- Yunnan Baiyao for dogs, another herbal supplement, can decrease blood loss from aggressive liver and splenic cancers like hemangiosarcoma.
Please consult your veterinarian or a veterinarian who is skilled in Traditional Chinese Veterinary Medicine (TCVM) if you are interested in trying these supplements for your dog with liver cancer.
In some cases, the therapies we discussed may not be the right option for your canine companion. Maybe the tumor isn’t amenable to treatment. Or perhaps the financial and time costs as well as the effects of the treatments on your dog’s quality of life are simply too much.
If you are in the second category, I want you to know that it is ok to forgo treatments and instead take steps to keep your dog comfortable as long as possible. Just because you can do a treatment doesn’t always mean you should.
Additionally, even if you do pursue treatment, there may come a time when it is no longer working. And then you will need to make the decision to shift the focus from addressing the tumor to keeping your dog comfortable.
In all of these situations, your vet can talk to you about the options for palliative therapies (i.e. comfort care). Liver cancer in dogs can be painful, especially if the mass is large enough to push on other internal organs. So your vet may prescribe pain medications to keep your dog comfortable. Or if your dog is nauseous or has a poor appetite, the vet might recommend anti-nausea medications like Cerenia for dogs or appetite stimulants for dogs.
What is the prognosis for liver cancer in dogs?
The life expectancy of a dog with liver cancer will depend on the type of mass present and its distribution. If it is a solitary tumor that can be removed with surgery, a dog can have a good prognosis and live for several more years, especially if the dog is middle-aged and the mass is benign.
Additionally, in dogs with massive (i.e. a solitary mass) hepatocellular carcinoma, surgical removal can be curative in some situations. In a study of 48 cases of dogs with massive hepatocellular carcinoma, dogs who did not undergo surgery were 15 times more likely to die from cancer complications than those who did.
Unfortunately though, most nodular and diffuse primary liver cancers, including bile duct carcinomas, neuroendocrine tumors, and mesenchymal cancers, carry a poor prognosis. The survival rate for dogs with these types of cancerous tumors is very low, and many will have a poor quality of life once other symptoms appear.
Final stages of liver cancer in dogs
In end-stage liver cancer, the dog may develop symptoms from the tumor itself or from tumor spread. Large hepatocellular carcinomas or tumors of the bile duct can obstruct the bile duct, leading to jaundice (i.e. yellowing of the skin), abdominal pain, and GI signs.
Additionally, liver cancer may spread to the dog’s lymph nodes, abdominal lining (i.e. peritoneum), or lungs. And dogs with hemangiosarcoma may suffer massive internal bleeding at any point, forcing dog parents to decide when to euthanize a dog with hemangiosarcoma.
Making the decision to euthanize your dog with liver cancer
If your dog has recently been diagnosed with liver cancer and the prognosis isn’t good, it can help to have a plan in place for your dog’s final days. You may want to talk to a vet who provides dog hospice care or have a conversation with your vet about how to keep your dog comfortable. And it might be a good idea to start filling out a quality of life scale for dogs on a regular basis so you can have an objective indicator of your dog’s wellbeing.
Preparing for your dog’s euthanasia is never easy. But remember that you don’t have to do it alone. Your friends and family can be there to support you. And I want to provide some resources which might help you in the journey:
- In-Home Dog Euthanasia: Heartfelt Answers to 12 FAQs
- Do Dogs Grieve? Helping Your Dog Cope With Loss
- Dog Memorial Ideas: 10 Ways to Honor Your Dog’s Legacy
- Dog Euthanasia: Knowing When to Say Goodbye
- Grieving the Loss of a Dog After Euthanasia (& Finding Peace)
- How Will You Know When It’s Time to Euthanize Your Dog? 5 Caring, Heartfelt Messages
Make the most of the days
Sometimes you get lucky and your dog’s liver tumor is benign or surgery is curative. But other times, a diagnosis of liver cancer does mean that the end is near for your dog. I wish I could take that pain away from you. But the best I can do is provide information and some words of comfort and encouragement to hopefully ease the pain a little.
So I’ll leave you with this thought. Dogs live each day in the moment. Even if you don’t have a lot more days left together, you have today. And you can make the most of it. Go to the pet store and pick out a new toy together. Snuggle on the couch and watch a movie. Take a walk and visit your dog’s favorite people and places.
You know what would make the day special for your dog. Hopefully, you have a lot more good days together. But even if you don’t, hang on to the memory of all the good days in the past and the ways you made your dog’s last days the best they could be.
Has your dog been diagnosed with liver cancer?
Please share your dog’s story or any words of encouragement for other dog parents.