Liver Tumor (Hepatocellular Adenoma) in Dogs

Hepatocellular adenomas are benign, while hepatocellular carcinomas are the malignant form. Studies show that the malignant form of the neoplasia (abnormal tissue growth) is the most common one, which is why all masses on the liver should be checked for cancerous properties. Even without a cancerous base, tumors of the liver can cause critical problems in that they can rupture and cause hemorrhaging. Tumors of the liver are most often found in older dogs, and usually appear as nodules of fibrous tissue. At present, there is no known breed or sex predisposition.

Hepatocellular Adenomas are benign tumors that arise from epithelial cells of the liver. This is a benign rare tumor that does not spread and offers a good prognosis with surgical removal.

Your dog may be asymptomatic even though he has a liver tumor, and it may be discovered during a routine examination upon palpation of the abdomen. In many cases, however, your pet could be quite ill before the presence of a hepatocellular adenoma is known.

• Vomiting
• Frequent bowel movements
• Increased thirst (polydipsia)
• Increased urination (polyuria)
• Low appetite
• Weakness
• Lethargy
• Abdominal swelling
• Jaundice
• Weight loss

Types

Hepatocellular adenoma is classified as a primary hepatobiliary neoplasia. Forms of the tumor are called solitary, nodular and diffuse. These tumors arise from glandular epithelial tissue and are usually clearly demarcated and well differentiated from the tissue of the liver.

Though scientists have not yet determined the reason that cancerous or noncancerous tumors form in humans and canines alike, there are some factors that could be attributed to the growth.

• Age
• Though not proven, liver flukes (parasitic organism) have been reported as a cause of tumor growth
• Environmental factors such as chemical exposure
• Hormonal changes
• Increased liver enzyme activity
• Genetics may play a role

It is interesting to note that less than 1% of all tumors seen in canines are tumors of liver cells. However, when they do occur, they often cause damage to other systems in the body, specifically because they are not found until they have advanced to the stage whereby they are serious.

The veterinary team will have questions for you that may help lead them to a diagnosis. It will be beneficial for the team to know what type of food you feed your pet, and how long he has been displaying the symptoms that brought him to the clinic. Behavioral changes are an important indicator of health, as are changes in bowel and urine habits. Be certain to give as much detail as possible in your discussions with the veterinarian. 

The veterinarian will have the technician assist as blood work is taken to look for markers that may suggest illness. A complete blood count and serum chemical profile will be done to check for abnormalities in liver enzyme levels. Additional important diagnostic tools are the radiograph, which can highlight areas that may appear different than they should, and the ultrasound, which can clearly show the presence of a mass.

Based on information provided by the abdominal ultrasound and further using the ultrasound as a guide, the veterinarian can take a fine needle aspirate of fluid from the mass to analyze the cells. A biopsy could be suggested as well and has been found to be an accurate way to positively determine if a hepatocellular adenoma is present.

The treatment protocol for a benign liver tumor of this type is surgery to remove the mass. Complete excision of the hepatocellular adenoma is the ideal scenario for full recovery. Fortunately, with the imaging tool of the ultrasound, determining the exact location and size of the growth is possible. This type of tumor is easily differentiated from normal liver tissue. 

When a tumor is removed from the liver, a surgical resection is necessary. Even with the removal of a large mass, the prognosis is good. Interestingly, up to 75% of the liver can be resected with the function of the liver remaining normal or near to normal.

During surgery, your beloved pet’s vital signs will be closely monitored at all times. Rest assured he will be kept comfortable, with the veterinary team keeping a close eye on oxygen levels, heart rate, and pulse.

Once your dog is ready to leave the hospital, the veterinarian will release him into your care with strict guidelines for recovery at home. You will need to administer pain medication if still required. Anti-inflammatories and antibiotics are necessary to avoid swelling and infection. Carefully monitor the incision; if you have any concerns about the recovery rate of your pet, contact the clinic immediately. Your veterinarian will need to see your furry family member in order to view the incision and the progress of healing a week after the surgery and then again, a week or two later.

The recovery should be fairly straightforward. Recurrence is possible if the tumor was not completely eliminated, but this type of growth removal is most often successful.