FIP and Feline Coronavirus: What an RT-PCR Result Means

A positive feline coronavirus RT-PCR result does not mean a cat has FIP. Many healthy cats carry the virus, and only a small number go on to develop FIP. Vets read the result together with the cat's signs, any fluid in the body and other tests to decide what it means for your cat.

What are feline coronavirus and FIP?

Feline coronavirus is a common virus of cats. It is a cat virus and not the virus behind COVID in people. It passes mostly through dung, so shared litter trays in homes, shelters and breeding places are a common route. Most infected cats show no signs, or only mild loose motions.

In a small number of cats the virus changes inside the body and causes FIP, short for feline infectious peritonitis. FIP is a serious illness. It is seen more often in young cats, though adults can be affected. Signs may include a fever that keeps coming back, a poor appetite, weight loss, a swollen belly, trouble breathing or changes in the eyes. A cat with such signs needs a vet promptly.

What can an RT-PCR result tell you?

The FCoV / FIP RT-PCR is an RT-PCR (real-time PCR) test. It looks for the genetic material of the virus in a sample, such as dung, a swab, blood or fluid.

A positive result on a stool or swab sample shows that the cat is carrying or passing the virus. That is common and is often harmless. On its own, the test cannot separate the harmless gut form of the virus from a form that has changed to cause FIP. A negative result does not always rule FIP out either, because the answer depends on the sample and the timing. This is why the result must be read with the cat's signs and other tests.

Which other tests help when FIP is suspected?

Vets often look at several pieces together.

• Body fluid. Some cats with FIP collect fluid in the belly or chest. A vet takes a sample of it, and the Rivalta Test is a simple test on that fluid that is commonly used as a screening step. It supports the vet's thinking and does not prove FIP by itself. The fluid may also go for RT-PCR and other tests.
• Antibodies. The Feline Coronavirus Antibody (ELISA) shows that a cat's body has met a coronavirus. Because so many healthy cats have, a positive result does not show FIP.
• Inflammation. The Feline SAA (Serum Amyloid A) measures serum amyloid A, a protein that rises with inflammation. It can show that the body is inflamed, or help follow a cat over time, but it does not name the cause.
• General blood tests. A blood count and blood chemistry give the wider picture of how the cat is coping.

If your cat's signs could fit more than one virus, the Cat Viral RT-PCR Panel may help. It typically groups RT-PCR tests for several cat viruses, and the exact list is confirmed when you book.

Why does careful wording matter?

The letters FIP frighten owners, and that fear can cut both ways. A positive coronavirus result in a bright, healthy cat should not cause panic. A positive result, or even a negative one, in a cat that is clearly unwell should not cause delay either.

A registered veterinarian looks at the cat's age, signs, living conditions and every result, and then explains what is likely and what is still uncertain. Please do not start any medicine on your own or from advice found online. Your vet will talk through the options that suit your cat.

How can you help your vet?

• Note when the signs began, how your cat is eating and drinking and whether the belly looks bigger.
• Mention how many cats share your home and whether any recently came from a shelter or another house.
• Tell the vet about earlier illnesses and test reports.
• If a vet draws fluid or collects a sample, keep it cool and labelled, and send it as advised.

Read next

If a sick cat also has bruises or bleeding, D-Dimer and Clotting Tests for Bleeding and Clot Risks explains clotting tests that vets sometimes add. For another illness where blood tests guide the vet, such as a cat that drinks and passes urine much more than usual, see Diabetes in Dogs and Cats: Glucose, Fructosamine and HbA1c.

Testing in Bhopal

To book, call or WhatsApp +91 88175 01118. The lab at C-200, C Sector, Shahpura collects samples from cats free anywhere in Bhopal, and fluid drawn by your vet can be sent in as advised. Owners in other districts can use a courier, a bus parcel or their own vet. The lab confirms the method, sample needs and reporting time when you book.