Beyond Nine Lives: Beware This Deadly Illness

This is a sponsored post by veterinarian Elizabeth Arguelles, owner of Just Cats Clinic at Lake Anne Plaza. She writes weekly on Reston Now.

Feline infectious peritonitis (FIP) is a viral disease affecting cats that is caused by certain strains of the feline coronavirus.

Though it can occur in any cat, it is most common in cats younger than two. Most strains of the coronavirus do not cause the disease, and most infected cats do not show any symptoms. This is because the development of viral antibodies often triggers an immune response.

But in about 5 to 10 percent of infected cats, the virus mutates into a more harmful form that causes FIP. When this happens, the white blood cells are infected with the virus and transport it throughout the cat’s body, causing an intense inflammatory reaction in the tissues where the infected cells are located. These are often in the abdomen, kidneys or brain.

How do cats become infected with the feline coronavirus?

Though it is not clear how most cats become infected with the virus, direct contact between cats is the most likely method of transmission. Biting insects such as fleas may also spread this virus.

Because the feline coronavirus is present in the infected cat’s blood in the early stages, it may be shed in the urine and feces even when the cat shows no clinical symptoms. The virus does not survive longer than 24 to 36 hours in normal weather, so transmission via clothing or other objects is also only possible within a few hours of contact.

What are the clinical signs and symptoms of FIP?

There are two major types of FIP, a noneffusive or dry form and an effusive or wet form. In general, cats will exhibit the symptoms of the noneffusive form more slowly. Those symptoms include chronic weight loss, anemia, lethargy, and a persistent fever that does not respond to medication.

In the effusive form of FIP, there might be an accumulation of fluid in the abdomen or the chest. Early on, the symptoms may be similar to those of the dry form. But the wet form of the disease often progresses more quickly, and the cat may seem potbellied due to the excessive fluid accumulation in the abdomen. And when there is excessive fluid accumulation, the cat may have difficulty breathing.

How is FIP diagnosed?

Unfortunately, there is no simple diagnostic test. The ELISA, IFA and virus neutralization tests detect the presence of the coronavirus antibodies in a cat, but they are not able to determine which strain is affecting the feline. So a positive result only means that the cat has been previously exposed to the virus.

These tests determine the antibody titer, so the higher the number, the greater the amount of antibodies. But a healthy cat with a high titer is not necessarily more likely to develop FIP than one with a low titer.

Other tests, such as the immuneperoxidase, detect the cells in tissues infected by the virus with the help of a biopsy.

Another antigen test uses a polymerase chain reaction to detect the virus in the tissues or body fluids, but also cannot identify the type of strain.

How is FIP treated?

Unfortunately, FIP is fatal in almost all cases. There is no specific treatment, and supportive care is the only option for cats affected by the disease. Anti-inflammatory drugs like corticosteroids, often used in conjunction with immunosuppressive drugs like the ones used in cancer treatments, may temporarily suppress the symptoms.

Once FIP has been diagnosed in a clinically ill cat, however, euthanasia may be the most humane course of action.

For more information, please visit our Feline Health Library.

If you’d like to help further FIP research, please visit the Cornell Feline Health Center to learn more.