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. Large-breed dogs appear to be affected more frequently than smaller breeds, though the tumour can develop in any dog. 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
Options & trade-offs
Last reviewed: Invalid Date ·