Question about FIP

Our question this week was:

Dr. Debra,

I recently worked at a Cattery that had an outbreak of FIP only 4 cats out of 100 tested 0 Titer level when all the cats were tested. Most of the cats tested 1600 and above is this normal?



Hi Lynn –thanks for your email. Your question is a good one but not a simple one. I’ll try to explain.

FIP stands for Feline Infectious Peritonitis. FIP is an infection that is caused by a virus called Corona Virus that is fatal to cats. An article that might be helpful that explains what is FIP and the symptoms it causes is on our site called Feline Infectious Peritonitis FIP.

How do cats get FIP? We used to think FIP was highly contagious. But this is no longer true. It is believed some cats infected with the relatively harmless form of the coronavirus will mutate the virus into the FIP virus. It is not transmitted cat to cat.

There are a couple types of Corona virus. One of them is not a big problem and the other one causes FIP. Many cats have the relatively benign form of the coronavirus.

A big problem has been that the tests to date have not been good at differentiating them between the FIP virus and the other corona virus. The most common blood test checks for exposure to the corona virus but does not differentiate between the viruses. So when a test comes up positive, it tells us that the cat has been exposed to corona only. However, a very high titer combined with a sick cat with clinical signs may be suggestive of FIP.

However, there is a newer test being done at Auburn University that is more definitive for diagnosing the FIP. I’ll give you the information form the University of Auburn College of Veterinary Medicine website:

Coronaviridae (such as FIPV) are enveloped RNA viruses that are common in the intestinal tract of cats. As yet uncharacterized mutations of the viral genome allow the virus to escape the intestinal tract and multiply in blood mononuclear cells. This causes the Feline Infectious Peritonitis disease syndrome.

This PCR test detects mRNA of the M gene of all known feline coronavirus strains in any sample; however, for diagnosis of FIP, only the detection of mRNA in blood is indicative since active replication of the virus in circulating mononuclear cells is typical for FIP. In contrast, avirulent feline coronavirus strains replicate in the intestinal tract, but not in blood mononuclear cells.