The most common liver disorders in cats are hepatic lipidosis, inflammatory hepatobiliary disease, neoplasia, extrahepatic bile duct obstruction, portosystemic shunt, acute toxic hepatopathy and secondary hepatobiliary disease.
Types of Liver Disease in Cats
Hepatic lipidosis, also called fatty liver disease, has become the most common liver disease of companion cats in North America. Most affected cats are over 2 years of age, but there does not seem to be a particular breed or gender predisposition. Hepatic lipidosis occurs when a cat’s body begins to break down stored fat for energy, and the byproducts of fat metabolism go to the liver to be processed. Affected cats are commonly obese, live indoors and have for some reason stopped eating. They lose weight rapidly, become jaundiced and dehydrated and vomit intermittently. A cat’s body is not equipped to metabolize fat for energy in this situation; the liver becomes damaged by the onslaught of fat byproducts. If the condition is not treated by complete nutritional support, it can be fatal.
Inflammatory Hepatobiliary Diseases - Cholangitis
Cholangitis is the term used to describe a group of diseases characterized by inflammation of the bile ducts. Because of the particular anatomical structure of cats, they are predisposed to infection from ascension of bacteria from the digestive tract into the bile ducts and pancreas, much more so than are dogs. The clinical signs of cholangitis, regardless of its cause, are similar: waxing and waning anorexia, depression, weight loss, vomiting, diarrhea, dehydration, enlarged liver and jaundice.
Primary hepatic neoplasia is uncommon in cats. Of the liver cancers that do cause clinical disease in cats, the most common are cholangiocellular carcinoma (bile duct) and hepatocellular carcinoma. Cancer tends to affect cats at the end stage of their lives. The clinical signs of hepatic neoplasia are nonspecific and include lethargy, anorexia, weight loss, abdominal distention and general malaise.
Extrahepatic Bile Duct Obstruction
This is a syndrome with several possible causes, including compressive tumors outside of the bile duct or intraluminal obstructive lesions. The clinical signs are largely indistinguishable from those of other causes of liver disease.
A portosystemic shunt is a congenital disorder where blood flows around rather than through the liver due to an anatomical vascular defect. This prevents the liver from extracting the waste products that it is responsible for doing, and thus waste products build up in the cat’s circulating blood.
Acute Toxic Hepatopathy
Liver disease can also occur if the liver is damaged by exposure to environmental or medical toxins. Cats are especially sensitive to acetaminophen and aspirin.