Liver Disease

Liver disease is a generic term used to describe any disease that affects the functioning or structure of the liver. The liver is a vital organ which sits within the abdomen. It performs several important roles such as protein and hormone synthesis, and metabolism and elimination of waste or toxic substances. There are many conditions which can result in liver disease in cats, whether directly or indirectly.

The clinical signs of liver disease can be very vague, for example, you may notice your cat has a generally reduced appetite, is being more quiet/lethargic than usual and that they have either slowly or quickly lost weight. Depending on the cause of the disease, you may see other signs such as vomiting, increased thirst, and an increased temperature. In more severe cases you may notice yellowing of your cat's eyes (where the eyes would normally look white), their gums and their skin, this is known as jaundice. Some cats may also suffer with excess fluid in their abdomen causing them to look bloated or as if they have suddenly gained weight.

There are several causes of liver disease in cats, some of the most common conditions include:

Neutrophilic cholangitis

This is an inflammatory disease of the liver resulting from a bacterial infection, which has usually travelled to the liver from the small intestine. The bacterial infection results in infiltration of the liver by large numbers of white blood cells called neutrophils. Cats with this disease may also suffer from inflammation of the small intestine and pancreas. This disease is usually acute in nature, meaning that cats will often present with more severe signs such as a high temperature, severe lethargy and jaundice, although it is possible for the disease to present chronically. It usually affects young to middle-age cats.

Lymphocytic cholangitis

This is another inflammatory disease of the liver. Unlike with neutrophilic cholangitis, the cause of lymphocytic cholangitis is unknown. It results in infiltration of the liver by white blood cells called lymphocytes and plasma cells. The disease is usually chronic in nature and symptoms such as reduced appetite, weight loss, vomiting and diarrhoea might appear to come and go, although it is possible for cats to suffer from more severe forms of the disease. The disease usually affects young to middle-age cats.

Hepatic lipidosis

This is a condition caused by accumulation of large amounts of fat (known as lipid) in the cells of the liver. This affects the structure and functioning of the cells. Hepatic lipidosis can be primary or secondary in nature.

Primary hepatic lipidosis occurs when a cat suffers a period of anorexia (complete loss of appetite) or stress, for example, due to a change in routine. This disrupts normal metabolism and causes accumulation of fat in the liver. It is most likely to affect overweight cats. The secondary form of the disease is triggered in response to other diseases such as diabetes mellitus, inflammatory bowel disease and pancreatitis. Clinical signs include anorexia and lethargy.

Toxin-induced liver disease

Cats may suffer from liver disease as a result of ingestion of a toxic substance or a certain type of drug. Clinical signs will depend on the toxin ingested although they are often acute in nature.

Other causes of liver disease in cats include liver tumours, amyloidosis (caused by accumulation of a protein in the liver), porto-systemic shunts (usually caused by a genetic condition which results in blood coming from the intestines to by-pass the liver), toxoplasmosis (caused by a parasitic organism called Toxoplasma gondii) and feline infectious peritonitis (FIP) (caused by feline coronavirus).

Blood and urine tests are usually an important first step for detecting liver disease in cats. Abnormalities that might be seen on these tests include:

• Increased liver enzymes in the blood (ALT, ALP, AST, GGT) - these are enzymes produced in the liver. If there is any damage to the liver or biliary system, these enzymes are released into the bloodstream.
• Increased bilirubin in the blood and urine - bilirubin is produced as a result of red blood cell breakdown in the spleen, it is filtered by the liver and excreted through the bile ducts. Liver disease may cause an increase in bilirubin in the blood or urine as it cannot be filtered and/or excreted, resulting in a build up.
• Increased bile acids in the blood - bile acids are produced in the liver from cholesterol. Your vet will be able to measure levels of bile acids in the blood before and after your cat eats a meal, this is called a bile acid stimulation test. This will give your vet an idea of whether the liver is functioning normally.

Other blood or urine parameters that can change as a result of liver disease include glucose, ammonia, blood urea nitrogen, cholesterol and proteins involved in blood coagulation. It is possible for other diseases such as hyperthyroidism or diabetes mellitus to cause changes in these blood and urine parameters as well. This means that liver disease can be complicated to diagnose.

Although blood and urine tests can give a useful indication that liver disease is present, your vet will not be able to diagnose the exact cause of the liver disease from these tests alone. Other diagnostic tools often required include ultrasound or x-rays of the liver (so that the liver can be visualised), and a liver biopsy.

A liver biopsy, which involves taking a small sample of the liver, is usually performed under general anaesthetic. Your vet will either use a needle to collect the biopsy with guidance from an ultrasound to visualise the needle in the abdomen, or they will need to perform surgery in order to open up the abdomen and collect the biopsy. The sample of the liver will be inspected under a microscope and, in most cases, the cause of the liver disease can be diagnosed.

Treatment will depend on the cause of the disease.

• Neutrophilic cholangitis is treated with a long course of antibiotics as well as supportive care such as intravenous fluids and drugs to help with liver function and blood clotting.
• Lymphocytic cholangitis is usually treated with immunosuppressive drugs such as steroids. It is possible for relapses to occur once treatment has ended and some cats need to stay on lifelong treatment.
• Hepatic lipidosis will often require a prolonged period of hospitalisation and nutritional support with the use of feeding tubes.

Whatever the cause, the liver is critical to your cat’s body functioning. As a result, supportive care will also be required to help them while, hopefully, the liver heals. In most cases this will revolve around good (low amount of high quality, and very palatable) nutrition, supplementation of certain substances the liver needs (silybin and SAMe, for example), potentially fluids and even feeding tubes.

Fortunately, the liver is highly regenerative and, with care and rapid treatment, many short-lasting liver diseases can be treated, allowing the liver to repair itself. Longer lasting conditions are more of a challenge, but can often be managed as a chronic illness.