Information on Viruses and Diseases – FIP

Information on Viruses and Diseases that Take the Ones we Love…

FIP is greatly misunderstood. Please read below.


FIP is a notoriously difficult condition to diagnose, and many other conditions present very similar clinical signs. FIP is caused by common strains of the coronavirus (FCoV) which in itself is a mild virus that usually runs its course in two weeks. Luckily, most cats don’t develop FIP from being exposed to feline coronavirus. Rather, the majority of exposed cats will show no signs of disease or only minimal ones, including a mild upper respiratory disease with sneezing, water eyes, a runny nose or a mild intestinal problem. Some cats will shed the virus for a brief time, but after several months, most will eliminate it and never be bothered again, unless they become reinfected.

Definitive diagnosis of FIP is only possible at post mortem, or occasionally by biopsy (though for accurate biopsy results one has to actually biopsy a visible pyogranulomatous lesion in either the abdomen or the lungs, which may necessitate laparotomy, which is surgery to gain access into the abdominal cavity through the abdominal wall). Only 18% of samples sent to a laboratory at the University of Glasgow that had a FIP diagnosis actually turned out to be FIP. Since cats with FIP are usually euthanized by the vets diagnosing them, it is absolutely vital that FIP is accurately differentiated from other, treatable, conditions. And therefore, RFW recommends that a FIP diagnosis is followed up with a second opinion from a vet who has not been given the FIP diagnosis.

In America, the FCoV RT-qPCR test is the one that RFW recommends, which is available from Dr Christian Leutenneger’ s laboratory at UC-Davis. You can download a sample submission form from his website. In addition, there is currently a relatively new drug available, a feline interferon omega by Virbac that cures one quarter to a third of the cases that actually have FIP. Naturally, it is our desire for no cats to contract FIP in the first place, never mind die from it, but do not automatically assume your cat has to be euthanized if you receive a diagnosis of FIP from a vet.