Inflammatory liver disease is second only to hepatic lipidosis as a cause of hepatobiliary disease in cats in the United States. Inflammatory liver diseases have been traditionally classified by their cellular infiltrate and pattern of distribution. The inflammatory cells involved are primarily neutrophils, lymphocytes and plasma cells which led to the descriptors neutrophilic, lymphocytic or lymphoplasmacytic. The cells may be found within the bile ducts, the epithelial cells lining the bile ducts, the hepatic parenchyma, and the gall bladder. These patterns of distribution have led to the use of the terms cholangitis, cholangiohepatitis and cholecystitis. Current classification schemes developed by the WSAVA Liver Standardization Group have led to the use of neutrophilic cholangitis and lymphocytic cholangitis to define the two major forms of inflammatory liver disease seen in the cat. Cholangitis less commonly consists of a mixed cellular infiltrate including neutrophils, lymphocytes, plasma cells, and occasional eosinophils. This mixed cholangitis is believed to be a more chronic form of neutrophilic cholangitis.

Signalment

There does not appear to be any breed or sex predisposition in the development of inflammatory liver disease although some of the original reports suggested that the disease was more common in Persians. Neutrophilic cholangitis is more common in older cats and lymphocytic cholangitis is more common in younger cats.

Neutrophilic cholangitis is believed to be due to bacterial infections originating from the gastrointestinal tract. Staphylococcus spp, E. coli and anaerobes are most commonly isolated. Most cases of lymphocytic cholangitis are idiopathic. Inflammatory bowel disease and pancreatitis have been associated with neutrophilic and lymphocytic cholangitis in cats. Helicobacter spp. have also been found in the bile and biliary ducts of a small number of cats with cholangitis. Liver flukes (Metorchis conjunctus, Parametorchis complexum, Platynosomum concinnum) have been associated with the development of cholangitis in the cat.

Clinical Signs

Clinical signs in cats with neutrophilic cholangitis are more acute and severe. Signs include lethargy, anorexia, vomiting, abdominal pain, icterus, and fever. Lymphocytic cholangitis tends to be more chronic with mild non-specific signs noted initially that become more severe and apparent as the disease progresses. Initially there may be mild weight loss that goes unnoticed followed by intermittent decreases in appetite, vomiting, diarrhea, and icterus. Some cats with lymphocytic cholangitis develop polyphagia, generalized lymphadenopathy and hepatomegaly. Ascites is uncommon but may occur due to portal hypertension in more chronic forms of lymphocytic cholangitis with extensive fibrosis, cirrhosis or sclerosing cholangitis. Acholic feces are also uncommon in cats but suggest complete obstruction of the common bile duct or severe sclerosing cholangitis.