The liver is a very important organ in the body. It is one of the largest organs in the cat and is located behind the lower ribs on the right side of the body. The liver is connected to the small intestine by the bile duct which carries bile (which is formed in the liver) into the intestines. All of the blood that leaves the stomach and intestines must pass through the liver before reaching its destination in the rest of the body. Thus the liver can be thought of as the main industrial center that processes nutrients and blood into forms that are easier for the rest of the body to use.
The liver itself has tremendous reserve capacity as well as a bit of regeneration capacity. These are both wonderful for keeping your cat healthy despite disease, but it can also mean that by the time you notice a problem the liver is 70-80% damaged. Thus at the first sign of a problem take your cat to the vet for an examination.
The liver has a number of functions in the body including:
- Production of blood enzymes, blood protein and clotting factors
- Production of bile and metabolism of bile salts
- Metabolism of cholesterol and protein
- Storage of glycogen and other nutrients
- Maintenance of blood sugar concentration
- Activation of B vitamines
- Hormonal regulation (ex. T4, GFT)
Cats can get a five different types of liver disease. Cholangitis or cholangiohepatitis is characterized by infection or inflammation of the bile ducts and/or liver. This inflammation can eventually lead to liver damage. This type of liver disease is usually seen in conjunction with other diseases such as FIP, FIV and FeLV. There are a few reasons that cholangitis or cholangiohepatitis can occur.
- Infectious disease (FIP, FIV)
- Parasitic condition (fluke infestation or toxoplasmosis)
- Bacterial infection of the liver or ducts
- Metabolic disease
Fatty liver disease or hepatic lipidosis occurs when fatty deposits build up in the liver. This usually occurs when the cat stops eating for some reason (this usually happens in conjunction with another disease). At that point the body will start to use the body’s fat stores for fuel. Unfortunately cats are not very good at using stored fat for energy and therefore fat can begin to accumulate in the liver. Hepatic lipidosis is generally not seen as the primary problem but is usually seen in response to some other disorder.
Toxic injury can be caused by poisoning, injury from bacterial toxins, or lack of blood to the liver. Symptoms of toxic injury will come on suddenly and necessitate immediate attention.
Portosystemic shunts occur when liver circulation is not fully functional, this can occur when incorrect connections between the arterial and venous blood flow are formed. When this happens the liver does not receive adequate blood and therefore can not perform its duties properly. This is generally a congenital condition.
Cancer of the liver can also occur, although it is rare in cats. There are several cancers that affect cats which have a tendency to spread to the liver including pancreatic cancer.
Symptoms to look for:
- Yellowing of skin and whites of the eyes (icterus)
- Ascite or a swollen fluid-filled belly
- Very yellow urine
- Appetite loss
- Weight loss
If your vet suspects liver damage he/she will perform a blood work-up and look for levels of:
- ALT (alanine aminotransferase). A rise in ALT occurs when the hepatocytes (liver cells) are damaged enough to leak through the cell membrane and release this enzyme. This can occur due to an acute attack on the liver from toxins, bacterial infection, blood supply deficiencies, bile duct obstruction and hepatic lipidosis.
- AST (aspartate aminotransferase). Rises of AST in conjunction with ALT can help confirm that liver disease is present. Basically there needs to be a bile duct blockage causing the liver cells to die in order for AST to be released. Testing for this enzyme can help point to the cause of the liver damage and show if there is cell death in conjunction with cell damage.
- ALKP (ALP, SAP, serum alkaline phosphatase). This enzyme is usually found in conjunction with bile duct obstruction.
- Bilirubin. This is a bile pigment and increased levels of it can indicate liver problems or the inability of the liver to properly break down bilirubin.
- Glucose, urea, albumin, globulin and bile acid levels.
Liver function can be evaluated using bile acid response testing. X-rays and ultrasounds can give indications of the size of the liver and can look for specific lesions in the liver or gall bladder. Of course a liver biopsy is the only completely conclusive way to determine liver disease.
Treatment varies with the specific type of liver disease and the extent of the liver disease. If your cat has cholangitis or cholangiohepatitis you need to stimulate your cat’s appetite and food intake. You can either do this manually or your vet may suggest having a stomach tube put in. This will start allowing the liver to function normally again since your cat will be getting calories from food and will no longer need to breakdown fats for energy. There are also appetite stimulants and anti-nausea drugs that your cat can take such as milk thistle (which also has beneficial effects on the liver) or valium. (See also appetite stimulation) You also may need to consider some dietary changes (high protein, low fat and adequate calorie diet) for your pet, if so your veterinarian will prescribe a proper diet for your cat. Your cat may also be put on a course of drug therapy most likely containing antibiotics, steroids and possibly immunosuppressive medications. Caught early and treated properly most liver problems are correctable and survivable.
NEW: A new supplement for liver disorders is now being investigated. It is known that glutathione, which is an antioxidant, helps protect liver cells (hepatocytes) from destruction and death. A new product from Nutramax Laboratories called Denosyl®SD4 contains S-adenyl-methionine (also called SAMe). Supplementing with SAMe has been shown to increase levels of glutathione in the feline body, thus helping the cat to have healthier liver cells! You should not give SAMe supplements without the advice of your veterinarian. These supplements should only be used with cats who have undergone liver damage, not for prevention of liver disease. If your cat has been diagnosed with a liver problem, ask your vet if SAMe might be right for her. If so he can prescribe Denosyl®SD4 for her in the proper dosage and set up a treatment schedule for her.
The best precaution for avoiding liver problems is to keep your cat on a healthy diet and at a healthy weight. Although there isn’t a clear 100% connection, obese cats have a higher tendency to get liver problems especially if they then undergo severe weight loss at some time point.
Also always keep an eye on your cat’s eating patterns and remember that even a few days of not eating can be a problem. Any cat who is not eating should be examined by a veterinarian to determine the cause.