Feline Infectious Peritonitis
Roger Ross DVM

On This Page:

This page is about feline infectious peritonitis which is also known as F.I.P.

A short introduction about the corona virus that causes this disease and then a discussion of the symptoms, diagnosis, treatment, and prevention of this fatal sickness in cats.

More about other respiratory diseases:

Back To The Main Page About Respiratory Problems in Dogs And Cats

Respiratory: Feline Asthma

Respiratory: Feline Upper Respiratory Complex (Colds)

Respiratory: Kennel Cough in Dogs

Laryngeal Paralysis in dogs

Collapsed Trachea in dogs

Respiratory: Heartworm disease in dogs and cats

Respiratory: Pneumonia

Respiratory: Fungal

On Other Pages about Infectious Diseases:
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Introduction page to infectious diseases in pets

Rabies in dogs and cats

Canine distemper (CDV) 

Canine parvovirus (CPV)

Infectious canine hepatitis (ICH)

Tracheobronchitis (CAV-2)
Kennel Cough


Canine herpesvirus (CHV)

Brucellosis in Dogs

Toxic Shock Syndrome in Canines caused by Streptococcus

Feline leukemia

Feline respiratory disease complex FVR, FCV, FPN

Feline Aids or (FIV)


About other cat topics on other pages:

Cats: our introductory pages to these fascinating creatures and their medical problems

Vaccine Recommendations for cats

What To Expect When You Take A Sick Cat To The Vet
Toxoplasmosis from Cats

Urine Spraying and Marking Behavior in Cats

Feline Asthma   
Feline Heartworm Disease

Feline Reproduction & Sex

A Short History of Cats
and an interesting article about cat extermination in Australia

There are lots of different subtypes of Corona Virus affecting people and animals. 

Many of these subtypes are harmless but some cause pretty serious diseases in some patients.

In cats, we have 3 main types of problems caused by Corona Virus:

1: Sometimes corona virus causes neural signs to include blindness and paralysis.  I discuss this disease on another page

2:  Sometimes corona virus causes diarrhea in kittens and is usually non fatal but can cause a life time of reduced health and recurrence of intestinal problems.
We refer to this problem as Feline CoronaVirus Enteritis and is discussed on another page.

3:  Unfortunately, the 3rd type of corona caused disease we have to deal with in feline medicine is often deadly and is know as FIP or Feline Infectious Peritonitis.  Peritonitis is a medical term referring to inflammation of the abdominal cavity.  But FIP also causes severe lung disease.

Feline Infectious Peritonitis (FIP)

Initial Comments and Symptoms:

Of the cats that get exposed to the virus, most show no symptoms at all.  Ever.

Many show no symptoms at first, but months later may get sick.

Some cats may show mild upper respiratory symptoms such as sneezing, watery eyes, and nasal discharge and then get better.

Other cats and especially kittens may experience a mild intestinal disease and show symptoms such as diarrhea and then get better.

And unfortunately, a few cats go on to develop full blown FIP and almost always end up dying.

In cats that develop FIP, the symptoms can appear to be sudden since cats have an amazing ability to mask disease until they are in a crisis state.

Once symptoms develop, often there is increasing severity over the course of several weeks, ending in death.

Generally, these cats first develop nonspecific symptoms such as loss of appetite, weight loss, depression, rough hair coat, and fever.

Other symptoms include anemia, persistent fever, a pot bellied appearance due to fluid in the belly and trouble breathing due to fluid in the lungs.


FIP is pretty easy to diagnois if the belly is obviously full of fluid and the patient is almost dead.  The problem is getting a diagnosis when you first bring your cat in because it's just not feeling up to par and not eating well.

There are no reliable screening tests for FIP
The blood work that most vets do when you have a sick cat will tell us that your cat is fighting off an infection or is anemic, but it won't tell us if the cause is FIP.

It's very inexpensive for us to place a syringe needle in your cat's belly to see if there is any yellow, syrupy fluid in the abdomen but this symptom doesn't occur until late in the disease.

Radiographs will often indicate fluid in the lungs and/or abdomen making us suspect FIP but again, this often isn't obvious until late in the disease.

Blood titers will tell us if your cat has been exposed to corona virus but won't distinguish between the non harmful strains of the virus or the deadly strains that causes FIP.
If we repeat the blood titer 7-21 days later and the titer is rising significantly while at the same time the patient is getting sicker, then we can conclude that your cat has FIP but by then your cat will be near death anyway.

Prevention:  There is a vaccine for FIP but most veterinary feline specialists seem to think the vaccine not very effective and the potential side effects are not worth the dubious benefit.

Unfortunately, there is no known cure or effective treatment for FIP at this time. Some treatments may induce short-term remissions in a small percentage of cats; however, FIP is a fatal disease. Treatment is generally aimed at supportive care, such as good nursing care and nutrition, and alleviating the inflammatory response of the disease. Cats with FIP are often treated with corticosteroids, cytotoxic drugs, and antibiotics. Supportive care may also include fluid therapy, draining accumulated fluids, and blood transfusions.

Research is ongoing to find other immunosuppressive drugs that may slow down the progress of the disease. Attempts are also being made to find antiviral drugs that will prevent or slow down the replication of the virus. One promising approach currently being studied combines both an antiviral agent and an immune response modifier.

Can I protect my cat from getting FIP?

In multiple cat environments, keeping cats as healthy as possible and minimizing exposure to infectious agents decreases the likelihood of cats developing FIP.

Litter boxes should be kept clean and located away from food and water dishes. Litter should be cleansed of feces daily, and the box should be thoroughly cleaned and disinfected regularly. Newly acquired cats and any cats that are suspected of being infected should be separated from other cats. Preventing overcrowding, keeping cats current on vaccinations, and providing proper nutrition can also help decrease the occurrence of FIP in groups of cats.

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This pictures is of the abdominal cavity of a cat that died of FIP.  Everything is a sickly color and notice the little granular plaques (looks like kosher salt) covering the surfaces of the intestines.  When the abdominal cavity was opened, thick yellow syrup like fluid leaked out.
Note the bloated belly
This disease affects the whole body but abdominal bloat, gastro-intestinal inflammation causing diarrhea, drastic weight loss, poor hair coats, lethargy, and respiratory-cold symptoms are what we notice first.