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Feline Infectious Peritonitis (FIP) in Cats: Symptoms and Treatments

Cat laying in bed

 

Our pets are susceptible to several viruses that are often similar to human illnesses, although not precisely the same. Feline Infectious Peritonitis (FIP) is caused by strains of the feline coronavirus, and it does not appear to pass between humans and cats. FIP is a severe condition that needs immediate attention if you suspect it in your feline.

Many strains of feline coronavirus hang out in your cat’s stomach, typically not causing many symptoms. If symptoms do occur, they are mild and often resolve on their own. But, in some cases, mutations can lead to FIPV and eventually Feline Infectious Peritonitis. Once it reaches this stage, the disease becomes progressive and is fatal in most cases, although new treatments are becoming available.

This information is not meant to scare you but to inform you so you can make the best choices for your cat’s health. Understanding the condition and its symptoms, treatments, and potential preventions are the best ways to keep your cat as healthy as possible.

A Closer Look at Feline Infectious Peritonitis

Most types of feline coronavirus live in your cat’s gastrointestinal tract. These strains are called feline enteric coronavirus (FeCV). Cats with FeCV may not show any symptoms or have mild diarrhea and respiratory issues. However, these symptoms typically resolve on their own within several days.

Most cats infected with FeCV develop an immune response within 7-10 days of infection. However, mutations occur in roughly 10% of cases, leading to FIPV. The virus spreads throughout the body as it infects white blood cells.

The cat’s immune system and the virus battle, leading to an inflammatory response. This response occurs in tissues where the infected cells reside, often in the brain or kidneys. Eventually, FIP develops, and once it does, it typically progresses.

There are two primary types of FIP, effusive and non-effusive. In non-effusive FIP, or dry FIP, cats can typically maintain some ability to eliminate parts of the virus. However, effusive or wet, FIP consists of fluid collecting in the chest or abdomen. Effusive FIP develops more rapidly, but effusive cases can become non-effusive and vice versa.

Symptoms of Feline Infectious Peritonitis

To understand the symptoms of FIP, first, you need to look at the signs of FeCV and FIPV. Initial exposure to FeCV may not show symptoms, eventually presenting with mild diarrhea, sneezing, nasal discharge, and watery eyes.

These symptoms often resolve on their own, but in a small percentage of cats, the infection develops into FIPV. FIPV symptoms include appetite loss, fever, depression, and weight loss. 

Noneffusive FIP will present the above signs and various neurological symptoms, like seizures or jerky movements. However, these symptoms will usually develop more slowly than in effusive FIP.

Symptoms of effusive FIP include all of the above and a pot-belly appearance if fluid gathers in the abdomen. Fluid can also collect in the chest, and you may notice breathing difficulties.

Are There Treatments for FIP?

Currently, there are no FDA-approved treatments for FIP. However, there is a drug in the process of trials that seems to have a positive effect on treating the effusive form of FIP. It also had a minimal impact on some non-effusive forms as well.

Right now, the drug is referred to as GS-441524, and it is best to discuss its use with your vet. Although you can find it for sale in some areas, the sources could be questionable. Your vet is still your best avenue of treatment before giving your cat this new potential drug or any medication.

Cat at vet

Can My Cat Get Feline Infectious Peritonitis?

Any cat can contract FIP, although the disease is more common in younger cats under two years old. It’s also more common in cats that live in large groups, such as shelters. Additionally, senior cats, male cats, and purebreds seem more susceptible to developing FIP, but there are no definite reasons to back up these observations.

Almost all cats will develop FeCV at some point in their lifetime. But a minimal amount goes on to develop FIP. Other cats with a higher chance of developing FIP are those under lots of stress and specific breeds, including Himalayans, Bengals, and Abssynians. Genetics can also play a role in your cat’s likelihood of developing FIP.

How Do I Know If My Cat Has FIP?

Overall, FIP is one of the least understood feline diseases, with no definitive test to diagnose it. Veterinarians can use methods to measure levels of feline coronavirus, but these methods don’t distinguish between FIP and FeCV.

Your vet will likely examine your cat for clinical signs of FIP, through routine blood tests, and more specific testing, like PCR tests. If clinical signs are present, they might look for some of the following in a regular blood test:

  • Low red blood cells
  • Elevated liver enzymes
  • Low numbers of lymphocytes and higher numbers of neutrophils (white blood cells)
  • Elevated bilirubin
  • Higher levels of globulin, which is a significant group of proteins in the blood

Then, if various PCR tests indicate a positive result, in addition to these signs, you would receive a diagnosis of FIP. However, a positive result by itself is not a sure sign of Feline Infectious Peritonitis.

If you suspect your cat may have FIP, your best bet is to bring your feline to the vet for assessment immediately. Through testing, diagnostics, and a complete examination, your vet will determine the likelihood of FIP being present.

Is There a Vaccine for Feline Infectious Peritonitis?

There is one licensed vaccine for FIP available. However, it is not often recommended by the American Animal Hospital Association. It is under their list of Not Recommended Vaccines.

One of the reasons is that the vaccine is for cats 16 weeks of age or older, and the majority of FIP cases develop in cats younger than this. Also, there is little evidence that this vaccine can reduce the incidence of FIP in real-world applications. However, the vaccine can make sense in some cases, so consult with your vet to see if it is a good idea for your cat.

Protecting Your Cat from FIP

If the vaccine isn’t recommended, what’s the best way to protect your cat from getting FIP? It’s worth remembering that although FeCV is highly contagious, FIP is not. Always make sure to keep your feline friend as healthy as they can be with proper recommended vaccines, keep litter clean and scoop frequently, and maintain fresh water and clean food dishes.

If you have multiple cats and you know one has FeCV, keep your other cats separate until the condition improves. Although this has not shown 100% efficacy in preventing FeCV, it’s still another way to help.

Taking Care of Your Friendly Feline

Knowledge is power when it comes to keeping your pets healthy. The more you know, the more likely you are to protect your cat from dangerous conditions and illnesses. If you ever suspect any problem with your furry friend, don’t hesitate. Make an appointment with your vet as soon as possible. 


You can find out about other pet issues in our blog, as well as all kinds of ways to care for your fur babies. It’s all about understanding your companion so you can do what’s best.

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