Hepatic lipidosis is the most common liver disease in cats in North America. In a retrospective study performed at the University
of Minnesota evaluating liver biopsy specimens obtained from cats over a 10-year period, hepatic lipidosis accounted for 50%
of all cases. Approximately 15% of cases were diagnosed as lymphocytic hepatitis, 11% as cholangiohepatitis, 10% neoplasia,
4% vacuolar degeneration, 3% congenital PSS, 2% toxic hepatopathy, 5% other. Greater than 75% of icteric cats have either
of the following: lipidosis, cholangitis, FIP, neoplasia (lymphoma).
Unlike in dogs, inflammatory liver disease of cats primarily involves the biliary tree. This disease was previously categorized
as acute or suppurative cholangitis/cholangiohepatitis, chronic or nonsuppurative lymphocytic, lymphoplasmacytic cholangitis/cholangiohepatitis
with (sclerosing cholangitis) or without destructive duct lesions. Recently these diseases have been re-categorized based
upon histopathologic features. As described by the World Small Animal Veterinary Association (WSAVA) Liver diseases and Standardization
Research Group 2006, inflammation of the bile duct can be differentiated into neutrophilic cholangitis, lymphocytic cholangitis,
destructive cholangitis (dogs), and chronic cholangitis associated with liver fluke infestation.14 Clinical differentiation of the subcategories of the cholangitis is unreliable without a liver biopsy because clinical features
are widely divergent; some cats show no signs and others present with severe acute illness.