Hepatic Neoplasia (Liver Tumors) in Dogs
Dr. Erika De Papp
A thorough history and physical exam are important in order to establish a diagnostic plan. Since the clinical signs of hepatic neoplasia can be quite vague, the physical exam is an important diagnostic tool. Many animals with hepatic neoplasia have an enlarged liver or a palpable mass in the abdomen. Free fluid in the abdominal cavity can also be recognized on physical exam, which may be an indication of bleeding into the abdomen or other fluid accumulation that is sometimes seen with liver disease. Physical exam may also suggest anemia (low red blood cell count) or reveal jaundice based on the appearance of the mucous membranes (gums, whites of the eyes).
Complete blood count. The CBC evaluates the red and white blood cells, as well as the platelets. Dogs with liver neoplasia may be anemic, especially if they have had internal bleeding. Red blood cell morphology (shape) may also be affected with certain tumor types. Elevations of the white blood cell count may also be noted, but this is a non-specific finding. Atypical or cancerous white blood cells may be seen in animals with hemolymphatic neoplasia. Animals that have had internal bleeding may also have reduced platelet numbers, as platelets are necessary for normal blood clotting and may be consumed when bleeding occurs.
Biochemical profile. The biochemical profile provides important information with respect to the liver. The enzymes produced by the liver are often elevated with hepatic neoplasia. Additionally, liver function can be partially assessed by measuring albumin (a blood protein made by the liver), blood sugar, bilirubin (a breakdown product of red blood cells that may be elevated with liver dysfunction, which results in jaundice), cholesterol, and blood urea nitrogen (a substance made in the liver from metabolism of protein). All of these parameters are measured on the biochemical profile. It is important to note however that abnormalities in these measurements can be seen with any type of liver disease and are not specific indicators of neoplasia.
Abdominal radiographs. Radiographs provide good information with respect to liver size and the presence of masses in the abdomen. Small masses may not be seen with routine radiographs. Fluid accumulation in the abdomen can also be noted on radiographs.
Thoracic radiographs. Radiographs of the thorax are important in cases where neoplasia is suspected, as the lungs are a common site of metastasis for many tumor types. Although metastatic disease can be present without showing up on the radiographs, the presence of metastasis in the lungs that is noted radiographically indicates that the disease has definitely spread to the lungs.
Abdominal ultrasound. Ultrasound often complements the findings on abdominal radiographs. It is a more sensitive means of examining the liver architecture. Additionally, it may be able to detect smaller masses, as well as evidence of locally enlarged lymph nodes and abnormalities in other abdominal organs. It is not as good at judging liver size compared to radiographs.
Coagulation profile. Tests of clotting function are imperative in animals with liver disease. The liver is responsible for making the vast majority of the body's clotting factors, so with liver dysfunction clotting can be abnormal. It is not common for animals with primary liver tumors to have defects in clotting ability, although it is important to test this prior to any invasive diagnostics, in order to assess the risk of bleeding. Additionally, if the tests are abnormal, specific therapy may be indicated.
Liver biopsy. Biopsy of the liver is necessary to make a diagnosis of hepatic neoplasia. Appearance of the liver alone is not a reliable method of diagnosis of neoplasia. With certain types of neoplasia, most notably the hemolymphatic cancers, diagnosis is made by fine needle aspiration and cytologic analysis (microscopic evaluation of the cells). However in the majority of cases, actual liver tissue must be obtained for microscopic review. This is important because an erroneous diagnosis of liver cancer might otherwise be made. The method used to obtain the biopsy may vary depending on the stability of the patient as well as the appearance of the masses associated with the liver and whether or not there appears to be multi-organ involvement. Biopsies may be obtained via ultrasound guidance, in which the abdomen is not opened; laparoscopy, using a small scope and biopsy instrument that are placed into the abdominal cavity; or abdominal surgery.