Neoplasia

Primary hepatobiliary neoplasia is rare in cats, but bile duct carcinoma and hepatocellular carcinoma are reported most often.¹⁰⁵

The systemic tumor most commonly affecting the liver of cats is lymphoma and related myeloproliferative diseases.

Clinical features

Clinical signs of hepatic neoplasia in cats are variable and are dependant on the tumor type and extension. Tumors of the hepatic parenchyma commonly cause hepatomegaly, while icterus is a rare finding seen in patients with other tumors, such as bile duct carcinomas.

Diagnosis

Abdominal ultrasonography may reveal generalized or focal lesions of the liver. Abnormal hepatic enzyme activities are common, but are nonspecific. The diagnosis should be con­firmed with histological or cytological examination of a liver biopsy.

Treatment

Surgical resection of a primary hepatobiliary neoplasm that is confined to one liver lobe and has not metastasized may result in prolonged survival. The size of the neoplasm is less impor­tant in determining the prognosis than the degree of invasive­ness and the presence of regional or distant metastases. The prognosis for cats with benign hepatocellular or biliary tumors after resection is good.

Key Facts

■ The diagnostic accuracy of histopathology is adequate if it is based on 2-3 biopsy specimens collected with a true-cut or Menghini biopsy needle. The recommended size of the biopsy instrument used is 14G in medium and large dogs and 16G in cats and small dogs.

■ In cats, hepatic encephalopathy may be due to portosystemic shunting or hepatic lipidosis. Hepatic encephalopathy in cats with hepatic lipidosis does not require dietary protein restriction.

■ Acute hepatitis in dogs may develop into chronic hepatitis, therefore re-evaluation of a liver biopsy 4-6 weeks after an acute epi­sode of hepatitis is indicated.

■ Evaluation of the course of most liver diseases requires repeated sampling of liver biopsies as results of blood tests do not provide adequate information.

■ Centrolobular copper accumulation in dogs is always due to a primary (genetic) copper storage disease and is not a result of cholestasis.

■ Feline neutrophilic cholangitis can only be definitively diagnosed by bile analysis. Gall bladder puncture should be performed routinely in suspected cases.

■ Treatment with corticosteroids has no long-term beneficial effects in cats with lymphocytic cholangitis.

■ The effect of most therapeutic strategies for hepatic and biliary diseases of dogs and cats are empirical and are not supported by relevant research.