There are many possible causes of liver disease in dogs and cats. Liver disease, also known as hepatitis, is a broad term describing a number of liver conditions. Since the liver has such important functions in the body, the development of liver disease may result in serious health consequences. The liver is responsible for building and breaking down fats, carbohydrates, and proteins, as well as storing vitamins, minerals, glycogen, and triglycerides. The liver also plays an important role in the production of red blood cells and produces factors important for the normal clotting of blood. Since the liver is an essential part of the immune system, liver disease may often lead to a serious immune deficiency syndrome. The liver also plays an important role in digesting nutrients and detoxifying chemicals and drugs taken into the body. When the liver is not functioning properly, toxins will build up, digestion will be affected, and there may be a shortage of essential nutrients, including glucose, vitamins, and minerals.
The potential causes of liver disease are numerous and include viral infections such as infectious canine hepatitis or feline infectious peritonitis virus, bacterial infections such as leptospirosis, certain parasites, toxins including pesticides or vaccinations, cancerous processes, and drugs such as Phenobarbitol, non-steroidal anti-inflammatory drugs (NSAIDs), and steroids. Obstruction of the bile ducts from the gall bladder may also lead to liver disease. In many cases, abnormal immune system responses may affect the liver potentially leading to liver disease. Other diseases, including diabetes, Cushing's Disease, hyperthyroidism, and pancreatitis all may cause secondary liver changes. Stress and obesity may predispose certain cats to hepatic lipidosis.
All pets are susceptible to liver disease. There are certain breeds, however, that are at increased risk. These breeds include Yorkshire Terriers, Cairn Terriers, Scottish Terriers, Schnauzers, Malteses, Golden and Labrador Retrievers, Poodles, and German Shepherds. There does not appear to be a breed predilection in cats, although obese cats are more prone to fatty liver disease, known as hepatic lipidosis. Younger pets are predisposed to a specific genetic circulatory problem of the liver known as a portosystemic shunt. This may lead to nervous system signs in severe cases.