CONDITION
Hepatocellular Carcinoma
Hepatocellular carcinoma is a type of cancer that originates in the liver cells themselves. It tends to develop as a single large mass within the liver, though sometimes multiple nodules form. This is distinct from cancers that spread to the liver from elsewhere in the body. Many dogs with hepatocellular carcinoma show no signs at all in the early stages, and a mass may be discovered incidentally during imaging for another reason or during routine health screening in older animals. When signs do appear, they are often vague—reduced appetite, weight loss, occasional vomiting, or a general sense that the dog is not quite right. Because the liver has significant reserve capacity, signs may not emerge until the tumour is quite large. In cats, this tumour is much less common. This page explores the signals that may prompt investigation, what is happening at a cellular level, how hepatocellular carcinoma is identified and staged, and the range of approaches that may be considered depending on the tumour's size, location, and whether it has spread beyond the liver.
Why this matters now
Hepatocellular carcinoma is predominantly a disease of older dogs, with most cases identified in animals over eight years of age. No consistent breed predisposition has been established for hepatocellular carcinoma in dogs. Some studies have found Welsh Corgis, Beagles, and Schnauzers overrepresented among affected dogs, but most report no clear link to breed or size. There is no clear link to specific dietary factors or environmental exposures, and the condition arises sporadically rather than in response to an identifiable trigger in most cases.
The tumour typically grows slowly over months to years, often remaining confined to a single lobe of the liver for a considerable period. Because the liver can function well even when a portion is replaced by tumour tissue, signs may not appear until the mass is quite large or begins to interfere with surrounding structures. In a proportion of cases, the tumour may eventually spread to other organs, most commonly the lungs or the membrane lining the abdomen, though this is less predictable than with some other cancers.
Signals & patterns
Early signals
Reduced appetite over days or weeks
An owner may notice the dog eating slightly less than usual, leaving food in the bowl more often, or showing less enthusiasm at mealtimes. This change is often subtle and can be mistaken for pickiness or seasonal variation.
Gradual weight loss
Weight may decline slowly, often without dramatic changes in behaviour. Because the loss is gradual, it can be difficult to pinpoint when it began, and it may only become apparent when comparing the dog's appearance to photographs from months earlier.
Occasional vomiting or nausea
Episodes of vomiting may occur intermittently, sometimes with no clear pattern or trigger. The dog may also show signs of nausea such as lip-licking, drooling, or reluctance to eat without actually vomiting.
Subtle shifts in energy or behaviour
The dog may seem slightly less engaged, sleeping more, or showing less interest in play or walks. These changes are often described as the dog being "not quite itself" rather than obviously unwell.
Incidental finding on imaging
In many cases, a mass is detected during an ultrasound or radiograph performed for an unrelated reason, such as investigating a heart murmur or following up on a routine blood test abnormality. The dog may have shown no signs at all.
Later signals
Abdominal swelling or distension
The abdomen may appear larger or feel fuller, either because the tumour itself has grown substantially or because fluid has begun to accumulate in the abdominal cavity. This may be noticeable when the dog lies down or when viewed from above.
Pale gums or weakness
If bleeding occurs within or around the tumour, the dog may become anaemic. Gums may look paler than usual, and the dog may tire more easily, breathe more rapidly, or seem unsteady.
Laboured breathing or coughing
If the tumour has spread to the lungs, the dog may breathe more heavily, cough intermittently, or seem less able to tolerate exertion. These signs reflect reduced lung capacity rather than heart disease.
Jaundice or yellowing
In some cases, the tumour may obstruct bile flow or cause sufficient liver damage that bilirubin accumulates in the blood. The whites of the eyes, gums, or skin may take on a yellowish tinge.
Click to read about the biological mechanisms
How this is usually investigated
Investigation typically begins with a careful history and physical examination, looking for any palpable abdominal masses or signs of discomfort. Because hepatocellular carcinoma often produces no specific signs, imaging is usually the next step, allowing visualisation of liver architecture and any focal masses. Blood tests help assess liver function and rule out other conditions, though they may be entirely normal in animals with localised tumours. Confirmation of the tumour type usually requires tissue sampling, either through biopsy or examination of surgically removed tissue.
Abdominal ultrasonography
Blood biochemistry
Thoracic radiography or CT
Cytology or biopsy
Advanced cross-sectional imaging (CT or MRI)
Options & trade-offs
Management of hepatocellular carcinoma is shaped by the tumour's size, location, whether it has spread, and the individual dog's overall health and temperament. Some tumours are amenable to surgical removal, particularly when confined to one or two liver lobes; others are monitored over time or managed with supportive measures. There is no single path that suits every animal, and decisions often reflect a balance between what is technically possible and what feels workable for the owner and the dog.
Surgical removal (hepatectomy)
When a tumour is localised to one or two liver lobes and there is no evidence of spread, surgical removal of the affected portion of liver may be considered. The liver has considerable regenerative capacity, and dogs can function well with a significant proportion of liver tissue removed. The operation is often performed by a specialist surgeon and carries risks associated with anaesthesia, bleeding, and post-operative recovery.
Trade-offs: Surgery offers the possibility of removing the tumour entirely, which may extend survival significantly if the cancer has not spread. It is a major procedure with a recovery period of several weeks, and not all tumours are positioned in a way that makes complete removal feasible. Older dogs or those with other health conditions may tolerate surgery less well.
Active monitoring
In dogs where a liver mass is discovered incidentally and remains small, or where surgery is declined, periodic imaging and blood tests may be used to track tumour growth and watch for signs of spread or deterioration in liver function. This approach allows time to assess the tumour's behaviour without immediate intervention.
Trade-offs: Monitoring avoids the risks of surgery and may be appropriate when a tumour is growing slowly and the dog remains comfortable. It does not alter the disease course, and there may come a point when the tumour's size or behaviour prompts reconsideration of other options.
Supportive and symptomatic care
For dogs with more advanced disease, large tumours that cannot be removed, or where age or concurrent illness makes surgery less suitable, care focuses on maintaining comfort and quality of life. This may include dietary adjustments, medications to manage nausea or pain, and monitoring for complications such as bleeding or fluid accumulation in the abdomen.
Trade-offs: This approach prioritises the dog's day-to-day experience and avoids interventions that carry significant risk or discomfort. It does not address the underlying tumour, and the disease will typically progress over time, requiring ongoing adjustment of care.
Chemotherapy
Chemotherapy is not commonly used as a primary treatment for hepatocellular carcinoma in dogs, as this tumour type tends not to respond predictably to cytotoxic drugs. In some cases, chemotherapy may be considered if there is evidence of spread or if the tumour cannot be fully removed, though responses are variable.
Trade-offs: Chemotherapy protocols for liver cancer in dogs are less well defined than for some other cancers, and benefits are uncertain. Treatment involves repeated visits and carries the possibility of side effects such as nausea or bone marrow suppression, which may affect quality of life.
Common misconceptions
"If my dog's liver blood tests are normal, there cannot be a significant liver tumour."
The liver has substantial reserve capacity, and a tumour confined to one or two lobes often leaves enough healthy tissue to maintain near-normal function. Blood tests reflect the overall activity of the liver rather than the presence or absence of a mass, and many dogs with hepatocellular carcinoma have entirely unremarkable biochemistry results, particularly in the early stages.
"Liver cancer in dogs is always aggressive and spreads quickly."
Hepatocellular carcinoma tends to grow slowly and often remains localised to the liver for months or years. While spread to the lungs or abdomen can occur, it is less predictable and less common than with some other cancer types. Many dogs live comfortably for a considerable period, particularly if the tumour is detected early and can be surgically removed.
"Diet or supplements can shrink a liver tumour."
There is no evidence that dietary changes, herbal remedies, or nutritional supplements reduce the size of hepatocellular carcinoma or alter its progression. Maintaining good overall nutrition supports liver function and general wellbeing, but this is distinct from influencing the behaviour of the cancer itself.
Related conditions
Cholangiocarcinoma
Cholangiocarcinoma arises from the bile duct cells within or near the liver, whilst hepatocellular carcinoma originates in the liver cells themselves. Both are primary liver cancers, and distinguishing between them often requires biopsy, as imaging and clinical signs can overlap considerably.
Hemangiosarcoma
Haemangiosarcoma can develop in the liver as well as other organs, and when a mass is found in the liver, both haemangiosarcoma and hepatocellular carcinoma may be considered. The two differ in their tissue of origin and biological behaviour, but imaging alone may not reliably distinguish them.
Splenic Mass
A splenic mass and a hepatic mass can present with similar vague signs—weight loss, reduced appetite, lethargy—and both may be discovered incidentally during abdominal imaging. Hepatocellular carcinoma may occasionally spread to the spleen, and conversely, some splenic tumours can metastasise to the liver.
Chronic Hepatitis in Dogs
Chronic hepatitis causes ongoing inflammation and damage to liver tissue over time, and there is some thought that long-standing liver inflammation may, in certain cases, contribute to an environment in which hepatocellular carcinoma can develop, though the relationship is not fully understood.
Cirrhosis in Dogs
Cirrhosis represents extensive scarring of the liver following chronic injury, and in some dogs with cirrhosis, hepatocellular carcinoma may arise within areas of regenerating or dysplastic tissue, though this progression is not inevitable.
Understanding how hepatocellular carcinoma fits into the broader landscape of liver disease in older dogs can be useful, as can exploring what 'staging' means in the context of cancer and how it shapes conversations about prognosis. The Longevity & Healthspan pillar offers context on age-related changes in organ function and the principles behind screening in senior animals. This may also be a point at which to think through what quality of life means for your individual dog and which trade-offs feel tolerable as part of ongoing care.