Feline inflammatory hepatobiliary disease is the second most common cause of liver disease in cats, with hepatic lipidosis being the most common. The disease is classified by hepatic histopathology¹ ; terms used to describe it have included suppurative or acute cholangiohepatitis, chronic cholangiohepatitis, chronic lymphocytic cholangitis, progressive lymphocytic cholangitis, sclerosing cholangitis, lymphocytic-plasmacytic cholangitis/cholangiohepatitis, lymphocytic portal hepatitis, and biliary cirrhosis.² A lack of consistency in terminology has made comparison of reported cases difficult and has hindered clarification of the etiopathogenesis of feline inflammatory hepatobiliary disease subtypes. In this review, we first discuss the general classifications of the disease and then describe how to diagnose and treat the various types.

CLASSIFICATION

A new classification scheme, proposed by the World Small Animal Veterinary Association (WSAVA) Liver Disease Standardization Group, recognizes that feline inflammatory hepatobiliary disease largely centers on the biliary tree.^3,4 They describe three distinct forms of feline inflammatory hepatobiliary disease: neutrophilic cholangitis (acute and chronic), lymphocytic cholangitis, and chronic cholangitis caused by fluke infestation.^3,4 Unfortunately, since there is not yet consensus within the veterinary community to use this scheme, for this review we use two broad categories of clinically relevant feline inflammatory hepatobiliary disease: acute suppurative and chronic nonsuppurative cholangitis. We also briefly discuss lymphocytic portal hepatitis.

1. Neutrophilic cholangitis. Neutrophils are present within the walls and lumina of the intrahepatic bile ducts and portal areas. Bile duct epithelial degeneration is also present. Microvesicular fatty change can be noted within the hepatocytes (hematoxylin-eosin stain; 400X).

Suppurative cholangitis is thought to be associated with infection.^1,5,6 This may be a primary biliary tree infection or an infection secondary to septicemia, dissemination of a chronic infection from another organ system, or treatment with systemic immunosuppressive therapy.¹ Many cats with suppurative cholangitis demonstrate disturbances in biliary structure and function that predispose them to ascending bacterial infections.^1,5,6 These disturbances can be anatomic, functional, or both. Many of these predisposing conditions have a waxing and waning course or result in subtle clinical signs (e.g. chronic pancreatitis, inflammatory bowel disease), so clinicians would not necessarily be able to determine whether the process was active. These predisposing factors may result in damage to the biliary tree that then results in abnormalities in biliary structure or function. Predisposing factors include inflammatory bowel disease, pancreatitis, abnormalities of gallbladder structure and function, choledochitis, biliary parasites, previous biliary diversion surgery, and extrahepatic bile duct obstruction.^1,5

The most commonly isolated organisms in cats with suppurative cholangitis are consistent with an enteric origin: Escherichia coli and alpha-hemolytic Streptococcus species, and Actinomyces, Enterobacter, Bacteroides, Klebsiella, and Clostridium species.² Additional organisms associated with suppurative cholangitis include Toxoplasma species and possibly Bartonella species. In many reported cases, however, a bacterial cause is suspected, but culture results are negative.² Reasons speculated for the failure to isolate bacteria include 1) lack of anaerobic culture submission, 2) difficulty in growing anaerobic organisms in vitro, and 3) previous antibiotic treatment.^1,2