Pets Are Important Too

Feline Portosystemic Shunt: Early Detection and Treatment Is Critical

by Aurore Fontai

The liver is one of the most important organs in a cat's body. It performs many functions that are crucial to a cat's well-being, and if compromised, the consequences can be serious, even lethal. One such condition is called a portosystemic shunt. The most common form of the disease is congenital, and a cat will typically begin to manifest symptoms during the first year of life. If your young friend begins to show signs of an underlying condition, it's important to get an early diagnosis. If it turns out to be a portosystemic shunt, the earlier treatment begins, the better the prognosis. Here's what you need to know.

The Liver

Liver function in a cat is very similar to that in a human. Its primary function is to filter or detoxify harmful substances in the blood before the blood circulates to the rest of the organs in the body. It also has a role in regulating blood glucose levels, storing vitamins, and synthesizing protein. It produces bile to aid digestion, as well as blood clotting factors and various hormones for use by other organs and systems.

The liver is the largest organ in a cat's body, and according to PetWave, it can still function when as much as half or more of its tissue mass is destroyed. That's good, but also bad, as by the time symptoms show, the liver destruction may be advanced and perhaps irreversible.

Portosystemic Shunt

A portosystemic shunt (PSS) is a congenital liver defect. It's a condition in which an abnormal blood vessel creates a bypass that diverts blood away from the liver. Instead of the blood being detoxified by the liver, it goes straight to the heart and then the rest of the body. The condition can also stunt the liver's growth because of the lack of blood supply.

The presence of poisons in the circulating blood can have profound effects on other bodily systems and cause kidney and digestive disorders, circulatory problems, neurological abnormalities, and growth problems. PSS, if not detected and corrected early, often results in death.

Symptoms and Diagnosis

First symptoms of PSS usually will appear during a cat's first year. Often, signs are subtle at first and include loss of appetite, lethargy, vomiting, and diarrhea. Such nonspecific symptoms don't often point to liver dysfunction. As the disease progresses, it may cause excessive salivation, disorientation, hyperactivity, distended abdomen, and yellowing of the whites of the eyes.

Your veterinarian will conduct a thorough medical history, physical exam, and blood and urine tests. If any of these point toward liver disease, he or she will perform ultrasound tests, radiographs, and vascular imaging to determine any blood flow abnormalities in or around the liver. The imaging can confirm the location and degree of shunting, which is crucial to determining a treatment plan.


Treatment of PSS in cats can be either medical or surgical and usually depends on the severity of the condition. Your vet will likely put your cat on a low-protein diet because the waste products from the breakdown of protein are toxic to the brain and other organs. Cats suffering from PSS often have stomach ulcers, so ulcer medications are often prescribed, as well as oral antibiotics. Unfortunately, these measures provide only a temporary subsiding of systems. The disease is progressive and will eventually require surgical intervention for permanent relief.

The surgery to correct PSS involves finding the bypassing blood vessel and constricting it so that blood is redirected through the liver. One problem with totally constricting blood flow is that it may cause a dramatic increase in blood pressure in the vessels of the liver. The development of a new device called an ameroid constrictor can help alleviate this problem. The ameroid constrictor is a metal band that is placed around the offending blood vessel. The lining of the constrictor absorbs fluid and expands, which slowly constricts the blood vessel. Because the constriction is slow, the liver can adjust without the increase in blood pressure.

If surgery or constriction can result in a complete shutdown of blood flow in the abnormal vessel, liver function will improve, and your cat can live a relatively normal life. If complete constriction is not achieved, a cat's condition will slowly deteriorate until further surgery or euthanasia will be necessary. Learn more about how you can prevent this by speaking with a representative from an animal hospital.