A yellowing of the skin and other tissues of the body is known as jaundice, but you might also hear the word ‘icterus’ being used to describe this process. The yellow colour is caused by excessive levels of bilirubin, a substance that comes from the breakdown of red blood cells. 

It can be tricky to notice jaundice in a cat, since most of their skin is covered by fur. But you might notice a yellowish hue around the ear flaps, whites of their eyes or gums. 

Regardless of the cause, jaundice is considered abnormal in cats, and is a sign of an underlying illness.

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What causes jaundice in cats?

Jaundice mainly arises because of:

  • Excessive destruction of red blood cells.
  • Liver disease.
  • Obstruction of the bile duct.

It’s also worth bearing in mind that there are several risk factors that might predispose a cat to developing jaundice, including:

  • Prolonged periods of not eating.
  • The presence of fleas or ticks.
  • Ingestion of drugs of toxins.
  • Infection with certain viruses (like FeLV and FIP)
  • Travel to areas where there is a risk of catching liver flukes or fungal diseases.

What causes the excessive destruction of red blood cells?

The process of red cell destruction is known as haemolysis. It can occur within blood vessels or in the spleen and liver. It happens all the time as a way of tidying up the blood vessels and keeping the blood healthy. However, excessive haemolysis causes a type of anaemia called haemolytic anaemia, and it also releases a lot of bilirubin into the system which causes the yellow appearance of jaundice. 

To diagnose haemolysis, a blood test is needed to determine the number of red blood cells, to find out whether the cat is anaemic. An examination of a blood smear will give an indication of whether the anaemia is caused by haemolysis. Haemolysis can be brought about by autoimmune disease, toxins, drugs, parasites on the surface of the red blood cells, or certain cancers, so additional tests will then be required to find out what the underlying cause of the haemolysis is. 

How is liver disease caused in cats?

Any disease or condition that damages or destroys liver cells can cause jaundice. This includes:

  • Inflammatory diseases of the liver and bile duct, like hepatitis, cholangitis, or cholangiohepatitis.
  • Hepatic lipidosis (a fatty infiltration of the liver).
  • Infections of the liver, caused by viruses, bacteria, or protozoa.
  • Toxins, such as heavy metals, or harmful chemicals. 
  • Certain drugs, such as diazepam, paracetamol and griseofulvin.
  • Liver cancers.
  • Cirrhosis (severe, end-stage liver disease).

A diagnosis of liver disease in the cat requires a blood test initially, to look at liver enzyme levels and total bilirubin. A bile acid analysis may be recommended in some cases, which tests for liver function. However, to diagnose exactly what the cause of a liver condition is, and whether or not it is reversible, requires a study of the liver tissue. Liver tissue can be obtained by passing a small needle into the liver with the cat under anaesthetic, or by taking a larger sample by opening the abdomen surgically to reach the liver. 

What causes obstruction of the bile duct?

Bile is needed for proper digestion. It is stored in the gallbladder and transported into the small intestine by the bile duct. 

Bile flow can become obstructed if:

  • Bile becomes abnormally thick.
  • The gallbladder or bile ducts become inflamed. 
  • Gallstones form in the gallbladder.
  • If the liver becomes swollen so that the bile ducts are constricted.  

Abdominal trauma, liver cancer and pancreatitis are all possible causes of bile duct obstruction. Cats suffering from an obstructed bile duct are usually very jaundiced, and suffer from vomiting, inappetence and weight loss. An ultrasound examination is usually the best way to confirm the presence of a bile duct obstruction, although some cats may require an exploratory surgery.

Can jaundice be treated?

The prognosis is dependent upon the underlying cause. Some diseases causing jaundice are sadly fatal, but others have a good prognosis for full recovery, especially if caught early. If you have concerns that your cat may unwell, or could be jaundiced, contact your vet straight away for advice.

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