The liver has many complex and diverse functions. It manufactures and excretes bile, which is necessary for proper fat absorption, it detoxifies and excretes many potential toxic substances, and it produces many blood proteins, including those necessary for normal blood clotting. Since the liver is responsible for the detoxification of many of the chemicals that enter the body, it is particularly susceptible to injury from those chemicals. Cats are subject to a number of life-threatening liver diseases.
The most common sign of severe liver disease, and the most noticeable, is jaundice. Cats that are jaundiced will have a yellowished cast to their skin, gums, and the sclera (white areas) of their eyes. Jaundice occurs because of an increase in the yellow-brown bile pigment bilirubin in the cat's blood stream. The liver is responsible for excreting bilirubin, a product in the breakdown of red blood cells. When the liver is not functioning properly, or if there is an obstruction to the flow of bile, which contains the bilirubin, the pigment will cause the animal to appear jaundiced.
Feline Idiopathic Hepatic Lipidosis
Feline idiopathic hepatic lipidosis, or fatty liver syndrome, is one of the least understood liver diseases that affect the cat's liver. It usually occurs in obese cats. The most common clinical sign is lack of appetite, which often lasts several weeks. Other signs may include lethargy and occasional vomiting and diarrhea. Treatment requires forced feeding of a balanced cat food diet until the cat will eat on its own. Because this forced feeding make take several weeks, it is often necessary to have a feeding tube placed into the cat's stomach. Hepatic lipidosis may also occur if cats who do not eat for several days. This condition is unique to cats. Even with very intensive treatment, this condition is frequently fatal.
Cholangiohepatitis, simply defined, is an inflammatory disorder of the hepato-biliary system which includes both liver and the bile excretory system. The causes of cholangiohepatitis are not well understood, but some cases are caused by bacterial infections. The final stage of this condition is cirrhosis. Treatment usually consists of antibiotics and cortisone-type drugs.
Bile is excreted from the liver through the bile ducts. Occasionally these will become obstructed. The most common causes are gallstones and sludged bile, which is associated with cholangiohepatitis. Inflammation of the pancreas and bile duct cancer can also cause a bile ducts obstruction. These cats are very ill, and surgery is the only way to remove the opbstruction.
Cats can develop cancer of the liver. Cancer can be either primary, developing from cells in the liver, or metastatic, which developed elsewhere in the body.
Some cats are born with a congenital anomaly of the blood vessels of the liver called a portosystemic shunt. In this condition the vessels that generally lead into the liver from the intestines bypass the liver and go immediately into the circulation. Because the blood bypasses the liver where detoxification occurs, kittens suffering from this condition have signs related to poisoning, such as loss of appetite, excessive salivation, depression, blindness, abnormal behavior and even seizures. Treatment involves surgical correction of any abnormal blood vessels.