Introduction

Feline cholangitis (CCH) is the second most common form of liver disease in cats (Sherding 2000). The WSAVA Liver Standardization Group describes three differ­ent forms of cholangitis: neutrophilic, subdi­vided into acute and chronic forms; lymphocytic; and cholangitis associated with liver flukes (Twedt, Armstrong, and Simpson 2014).

Neutrophilic (suppurative/exudative)

CCH can be subdivided pathologically into an acute neutrophilic form (predominantly neutrophilic infiltration) and a chronic neu­trophilic form (mixed cellular infiltrate of neutrophils, lymphocytes, and plasma cells). The cause of the acute form is thought to be bacterial from gastrointestinal origin, whereas the chronic form may represent a later stage of the same disease process, pos­sibly triggered by persistent infection or inflammation. Bacterial entry by either the biliary system or hematogenous spread is possible. In lymphocytic (non-suppurative/ lymphoplasmacytic) CCH, the cellular infiltrate consists mainly of lymphocytes and plasma cells. It tends to be more chronic and slowly progressive than neutrophilic CCH. Preliminary immunologic studies suggest that lymphocytic CCH could have an immune-mediated cause (Zoran 2012).

CCH has been described in a wide age range of cats, but cats with neutrophilic CCH tend to be younger (median age of 9 years) than those with lymphocytic CCH (median age 11.5 years) at the time of diagnosis (Sherding 2000). In some reports on lympho­cytic CCH, a male predisposition was found, with Norwegian Forest cats overrepresented (Otte et al.

Affected cats with either type of CCH show clinical signs of anorexia, weight loss, lethargy, and vomiting. Cats are usually icteric, and a few may have ascites. Patients with neutrophilic CCH usually present for an acute onset of illness and pyrexia is often seen. In lymphocytic CCH, the signs are often intermittent and tend to wax and wane over months (Gagne et al. 1999). Polyphagia is sometimes seen in these cases. With neu­trophilic CCH cats are usually febrile, dehy­drated, and icteric and may have abdominal discomfort with palpation, while cats with lymphocytic CCH may have minimal physi­cal examination abnormalities or may pre­sent icteric with hepatomegaly on abdominal palpation (Gagne et al. 1999).

Frequent concurrent disorders in CCH cats include extra-hepatic bile duct obstruc­tion, cholelithiasis, gall bladder abnormali­ties (sludge, cholecystitis), chronic subclinical pancreatitis, and inflammatory bowel dis­ease. Because of the feline pancreatic and bile duct anatomy, it is common for cats to have CCH and pancreatitis simultaneously and in some cases; cats will also have concurrent IBD. The constellation of the three condi­tions occurring together is called triaditis. This combination is increasingly recognized in cats, and recent reports suggest 50-85 % of cats with one syndrome have all three dis­eases (Zoran 2012). Anorexia induced by CCH may also lead to secondary hepatic lipi­dosis (Twedt et al. 2014).