There are two different types of liver cancer in dogs, primary and metastatic neoplasia. The liver plays an important role in detoxifying substances that circulates in the body. The purpose of the liver also includes metabolism, break-down of red blood cells, protein synthesis and glycogen storage. Masses that are found on the liver can be benign or malignant. Studies show that older dogs have a greater risk of developing liver cancer.
Primary
Primary liver cancer originates in the liver and often spreads to other organs. Primary cancer is rare and is seen in less than 1.5 percent of dog cancers. It has been studied that exposure to carcinogens or toxic chemicals can increase your dogs chances of developing primary liver cancer. When a substance is digested it can become more toxic as it is metabolized. Some carcinogens that are harmful to your dog can be rotten pet food, dyes, food additives, animal tissue and certain plants.
The most common primary liver cancer is hepatocellular carcinoma. Most hepatocellular carcinomas occur on the left side of the liver. There are three form in which the tumor can be classified, massive, nodular or diffuse. The massive form involves a single mass on one liver lobe. This form makes up more than 50 percent of cancer cases. The nodular form involves nodules in several liver lobes with 16 to 29 percent of cases. Only 10 percent of the hepatocellular carcinoma cases are from the diffuse form.
Metastatic Disease and Cancer
When cancer is spread from it's original site affecting the liver it is known as metastatic liver cancer. This is the most common type of liver cancer. This occurs with the spreading of cancer cells through the lymphatic system or the blood stream. The most common cancer that metastasizes to the liver is lymphosarcoma followed by tumors of the blood vessels and pancreas. With the different functions that the liver preforms, cancer cells pass through the liver from different areas of the body passing on cancer cells.
Symptoms of Liver Cancer
If your dog has a benign tumor the tumor will not spread and he will show no symptoms, unless it has ruptures or bleeds. If he has a malignant tumor he may show some or all of these symptoms.
- lack of appetite
- weight loss
- vomiting
- lethargy
- increase thirst
- increase urine
- fluid in peritoneal cavity (abdomen)
- pale gums
- jaundice
- difficulty breathing
- weakness
- ataxia (no muscle control)
- seizures
Diagnosing Canine Liver Cancer
Liver tumors can only be diagnosed by a veterinarian. With the completion of a blood profile test they will find an increase in the white blood cell count, a lack of red blood cells and a increase in the platelet count. The liver enzymes may be elevated, but are not exclusive to liver tumors. If a tumor is suspected, x- rays, MRI, CT scan, or an ultrasound may be performed. The preferred method is an ultrasound but a MRI or CT scan provides more information. Needle aspirations or needle core biopsies can be performed to confirm if the cancer is benign or malignant. This procedure involves tissue samples or cells from the tumor evaluated by a veterinary laboratory.
Treatment for Liver Cancer in Dogs
Depending on the severity of the liver cancer, surgery can be preformed. Massive hepatic carcinoma has been known to be successful due to the cancer affecting a certain lobe. Because of the complexity of nodular and diffused cancer forms, surgery is not usually an option. Pain medications are given to your dog to relieve pain and assist in comfort. Radiation and chemotherapy has not been studied on dogs with liver tumors.