Hepatic lipidosis (fatty liver disease) is a common disease of the feline liver in which abnormally large amounts of lipid (fat) accumulates within the cells of the liver. In other animals (humans, dogs, laboratory animals), lipid accumulation tends to be harmless, however, the cat's unique pathways of protein and fat metabolism cause lipid accumulation in the liver to have severe consequences. Any breed of cat may be affected, and both sexes seem to be affected equally. Middle aged to older cats are more susceptible than young cats.

Most, but not all, affected cats have a history of being obese, as well as a history of a sudden loss of appetite, often precipitated by a stressful event, such as a move to a new home, separation from an owner, a new pet or family member in the household, or a sudden switch to an unpalatable food. Anorexia, depression, and intermittent vomiting are the first signs usually noted by the cat owner. As liver function worsens, cats may develop jaundice (a yellow discoloration to the whites of the eyes, gums, and skin), severe loss of muscle mass, drooling, and signs of mental dysfunction (severe depression, sudden blindness, seizures). Cats often lose at least 25 percent of their body weight. The diagnostic tests recommended will help differentiate hepatic lipidosis from other liver diseases such as:

Cholangiohepatitis - an infection or inflammation of the liver and bile ducts

Feline infectious peritonitis - a deadly viral disease that can affect many organs, including the liver

Toxic liver disease - caused by ingestion of a drug or other harmful toxin

Liver cancer

Feline leukemia virus

Parasites - such as liver flukes (uncommon)