Hepatic Neoplasia (Liver Tumors) in Dogs

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Overview of Canine Liver Cancer 

Hepatic neoplasia is cancer of the liver which can occur in dogs. The words cancer, neoplasia or neoplasm, and tumor are often used interchangeably. Neoplasia in the liver may be the result of a primary liver tumor (one that originates in the liver), hemolymphatic cancer (arising from blood cells or lymphoid tissue) that involves the liver, or metastatic cancer (cancer that has spread to the liver from other organs).

The most common form of liver cancer in dogs is metastatic disease. Primary liver cancer is rare, comprising less than two percent of all cancer seen in these species. When it does occur, the most common primary liver tumors seen in dogs are hepatocellular carcinomas, which are malignant tumors that arise from the liver cells, and hepatocellular adenomas or hepatomas, which are benign tumors that arise from the liver cells.

The cause of primary liver cancer may be related to environmental factors. Exposure to carcinogens, or cancer-causing chemicals, may increase the risk of cancer development. Many chemicals are not toxic until they are metabolized by the liver. The liver serves an important role in detoxifying many substances circulating in the body. However, some chemicals are made more toxic after they have been broken down by the liver. Examples of possible carcinogens include toxins produced by fungi that are sometimes associated with spoiled pet food, food additives, certain pesticides, dyes, plants and animal tissue. Viral infections have been associated with hepatic cancer in humans. This has not been shown in dogs.

Primary liver cancer is most common in pets greater than 10 years of age. There is a slightly increased risk of hepatocellular carcinoma in males compared to females.

The impact of the disease on the pet varies depending on the tumor type. Benign tumors do not spread and generally do not cause illness unless they are physically impinging on other abdominal organs, or if they rupture and bleed. Occasionally, large benign liver tumors cause hypoglycemia (low blood sugar) by probable release of insulin-like substances. Insulin is the hormone that controls blood sugar levels, and is normally produced by the pancreas.

What to Watch For

Signs of liver cancer in dogs may include: 

  • Vomiting
  • Decreased appetite
  • Abdominal distension
  • Pale gums
  • Generalized weakness
  • Increased respiratory rate
  • Difficulty breathing
  • Jaundice (yellow discoloration of the skin)
  • Weight loss
  • Malignant tumors carry a much graver prognosis as these are aggressive disease processes and often have evidence of widespread involvement by the time of diagnosis. Just as other tumors can metastasize to the liver, primary liver tumors can metastasize to other organs. The symptoms are often vague and non-specific.

    Diagnosis of Hepatic Neoplasia in Dogs

  • History and physical exam
  • Complete blood count (CBC)
  • Biochemical profile
  • Abdominal radiographs (x-rays)
  • Thoracic (chest) radiographs
  • Abdominal ultrasound
  • Coagulation profile (clotting tests)
  • Liver biopsy
  • Treatment of Hepatic Neoplasia in Dogs

  • Medical stabilization, which may require IV fluids and blood transfusions in certain cases
  • Surgical mass removal when possible
  • Chemotherapy, depending on the tumor type
  • Home Care and Prevention

    Administer all medications as prescribed by your veterinarian. Monitor your pet for abdominal distension, pale gums, extreme weakness, anorexia, vomiting or diarrhea.

    Feed a high quality pet food and provide proper storage to insure freshness of the food. Discard any food that appears to be spoiled.

    In-depth Information on Hepatic Neoplasia in Dogs

    Although hepatocellular tumors and tumors of the biliary tract are the most common primary liver tumors, other tumor types may also occur. These include:

  • Hemangiosarcoma – a malignant tumor that originates from blood vessels
  • Hemangioma – a benign tumor that originates from blood vessels
  • Fibrosarcoma – a malignant tumor that originates from connective tissue
  • Leiomyosarcoma – a malignant tumor originating from smooth muscle
  • Carcinoids – a malignant tumor arising from specialized endocrine cells.

    Hemolymphatic tumors that often involve the liver include:

  • Lymphosarcoma – a tumor of the lymph nodes and lymphatic tissue
  • Mast cell tumors – mast cells are involved in allergic responses and can become malignant and form tumors
  • Leukemia – cancers that arise from blood cells
  • Multiple myeloma – a type of cancer that arises from specialized antibody producing cells

    The liver is the most common organ involved in metastatic disease, or spread of malignant cancer. Many tumor types may metastasize to the liver. Because the symptoms of hepatic neoplasia are often quite vague, there are any number of other disease processes that may cause similar signs. In cases of metastatic disease, the signs are often related to the site of the primary cancer. Generally the initial diagnostic work-up allows recognition of some type of liver problem. Other liver diseases that may cause similar symptoms include:

  • Hepatitis or cholangiohepatitis. These are inflammatory conditions of the liver, or liver and biliary or bile transport system.
  • Hepatic abscesses. Abscesses in the liver are bacterial infections with associated pockets of pus similar to an abscess your pet could develop in the skin.
  • Hepatic hematomas. Hematomas are large collections of clotted blood that may occur in the liver secondary to trauma or secondary to ruptured portions of the liver. The hematomas usually do not cause clinical problems unless they begin to bleed profusely.
  • Hepatic necrosis. Necrosis or cell death of the liver may occur secondary to toxins or adverse drug reactions.
  • Leptospirosis. This is an infectious liver disease of dogs, caused by a particular type of bacteria called a spirochete. It can cause both liver and kidney damage and subsequent inflammation of these organs.
  • Hepatic flukes. Flukes are parasites that invade the liver. They are quite rare.
  • Hepatic viral infections. Viruses that target the liver include canine infectious hepatitis virus in dogs. As with other infectious causes, these animals usually have more than one body system involved.
  • Fungal infections. Systemic (widespread) fungal infections can involve the liver. Individual fungi are limited to certain geographic regions of the United States.
  • Liver lobe torsion. In rare instances, part of the liver may become twisted. This may happen following trauma or can occur spontaneously.
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