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Jaundice is actually a condition called icterus, meaning that a yellow pigment is found in the blood and in the tissues. It is most easily seen in the gums, the whites of eyes and the earflaps.

Causes & Symptoms
Risk factors for icterus may include the presence of fleas or ticks, infection with feline leukemia virus or feline infectious peritonitis virus, residence in or travel to areas endemic for liver flukes or fungal diseases, prolonged anorexia and ingestion of drugs or toxins. A yellow color is noted in the skin, white part of the eyes, or on the earflaps. The causes of icterus fall into 3 major categories:

1. Destruction of red blood cells
This can occur within the blood vessels (intravascular) or in the spleen and liver (extravascular). The process of red cell destruction is known as hemolysis.

2. Liver disease
Any disease that causes destruction of liver cells or causes bile to become trapped in the liver can cause icterus.

3. Obstruction of the bile duct
The bile duct carries an important fluid for digestion, bile, from the gall bladder to the small intestine. Obstruction can occur within the gall bladder or anywhere along the bile duct.

Diagnosis
Diagnosis of icterus itself is straightforward. However, determining the cause of icterus can be a challenge and usually requires a series of tests. Within each category listed above are several possible causes of icterus. Once the probable cause can be placed into one of these 3 categories, additional tests are performed to look for a specific disease, which is leading to the icteric state.

Occasionally, blood is drawn and the serum component is found to be yellow before the cat is visibly jaundiced. This information is helpful and can give a clue to impending problems.

Hemolysis
Since hemolysis results in destruction of erythrocytes (red blood cells), determination of erythrocyte numbers is one of the first tests performed on the icteric patient. There are 3 tests, which may be used for this. Toxic plants, chemicals, drugs, parasites in the red blood cells, heartworms, autoimmune diseases and cancer can cause hemolysis. Several tests are needed to determine which of these is the cause.

Liver Disease
A chemistry profile is performed on cats with icterus. This is a group of 20 – 30 tests that are performed on a blood sample. The chemistry profile contains several tests that are specific for liver disease. If these tests are normal yet there is reason to suspect liver disease, a bile acid analysis is performed. Although each of these tests is used to ‘look’ at the liver from a slightly different perspective, ultimately they only determine that liver disease is present. None of them are able to determine the exact cause of the disease, to make that determination; a study of liver tissue (biopsy) or liver cells (cytology) is necessary. This can be done in 3 ways:

1. Fine-needle aspirate cytology
To perform this procedure, a small gauge needle is inserted through the skin into the liver. A syringe is used to aspirate some cells from the liver. The cells are placed on a glass slide, stained and studied under a microscope.

2. Needle biopsy
This procedure is similar to fine-needle aspirate except a much larger needle is used. The needle is able to recover a core of tissue, not just a few cells. The sample is fixed in formaldehyde and submitted to a pathologist for analysis.

3. Surgical wedge biopsy
The cat is placed under general anesthesia, and the abdomen is opened surgically. This permits direct visualization of the liver so the exact site for biopsy can be chosen. A piece of the liver is surgically removed using a scalpel. This approach gives the most reliable biopsy sample but the stress of surgery and the expense are the greatest of all of the biopsy methods. Some of the causes of liver-related icterus include infectious diseases (feline leukemia, feline infectious peritonitis, fungal disease), neoplasia and hepatic lipidosis (fatty liver diseases)

4. Bile duct obstruction
Cats with obstructed bile ducts are usually extremely icteric. Their yellow color can often be seen readily in the skin, as well as the sclera (whites of the eyes) and gingival (gums). However, an evaluation of the gall bladder and bile ducts is necessary to be sure that obstruction is present. An ultrasound examination is the most accurate and non-invasive way to evaluate the gall bladder and bile duct. This technology uses sound waves to ‘look’ at the liver, gall bladder and bile duct. If this is not available, x-rays should be taken of the liver. However, sometimes exploratory surgery is necessary to properly evaluate the cat for biliary obstruction. The most common causes of bile duct obstruction include pancreatitis, trauma, cancer, gall bladder stones, liver flukes, and severely thickened bile.

Treatment & Recovery
Icterus is not a disease; it is a sign that disease is present. Therefore, there is no specific treatment. Icterus will resolve when the disease that causes it is cured. The basis for resolving icterus is to diagnose the underlying disease. When the proper testing is done, this is usually possible. The prognosis is dependent upon the underlying cause. Some diseases causing icterus are fatal but others have a good prognosis for full recovery

Taken from Clubpets: Your lifestyle pet magazine (Issue no. 15: Feb – May 2005)