Bringing home a new kitten should be a joyous time. But for many, an aggressive virus brings tragedy, often proving fatal in a matter of weeks.

Feline infectious peritonitis (FIP) is a mysterious, devastating illness that most commonly affects kittens, especially those that have been exposed to multi-cat indoor environments like animal shelters. In honor of National Feline Infectious Peritonitis (FIP) Awareness Day, learn what causes this disease and what you can do to protect your kitten.
 

What Is FIP in Cats?

Feline infectious peritonitis (FIP) is a mutated strain of a virus called feline enteric coronavirus (FeCV). An estimated 50% of cats will be exposed to FeCV in their lifetime, and usually, the virus is limited to the gastric tract.

The majority of cats that contract FeCV will experience mild symptoms like diarrhea that lasts a few weeks, and many do not experience any symptoms at all. For an unlucky 10% of affected cats, though, the virus mutates into FIPV. The mutated virus attacks white blood cells, spreading from the gastric system to the bloodstream and throughout the body.

In cats with FIPV, the virus attacks the immune system, causing an inflammatory response that leads to severe illness, multiple system organ failure and, in a matter of weeks or months, death.
 

What Causes FIP in Cats?

It’s unclear why most cats clear the virus without complications, while others develop fatal FIP. Kittens face a risk of developing FIP at about five to seven weeks of age, when they’re no longer taking in protective antibodies from their mother’s milk. Cats under two years of age are usually affected, though geriatric cats are also at risk, possibly due to the virus coming out of dormancy with compromised immunity due to chronic illness or stress.
 

What Are The Symptoms of FIP in Cats?

Early signs of FIP are typically nonspecific. Cats and kittens tend to show general signs of being unwell, like lethargy, poor appetite, and fever. Upper respiratory symptoms like eye discharge and sneezing may also be seen.

There are two types of FIP. Effusive or “wet” FIP is most common, and typically affects kittens, while older cats are more likely to be affected by non-effusive or “dry” FIP.
 

Symptoms of Wet or Effusive FIP

• Fluid accumulation in belly
• Difficulty breathing
• Organ failure
• Fever
• Eye discharge
• Rapid onset of symptoms

Symptoms of Dry or Non-Effusive FIP

• Neurological signs like seizures and tremors
• Vision loss
• Organ failure
• Fever
• Eye discharge
• Slow, gradual onset of symptoms

As the virus spreads through the body, affected cats can develop a combination of dry and wet FIP symptoms.
 

Prevention of FIP in Cats

While there is a vaccine for FIP, it is generally not recommended because it cannot be administered in cats younger than 16 weeks of age, and most cats will have been exposed to the virus by then.

The only way to prevent the development of FIP in cats is to protect your kitten from being exposed to FeCV. Some cats are carriers and will asymptomatically shed the virus throughout their life.

The virus can spread through multiple different modes of transmission. It is spread through the feces, particularly in cats that share a litter box. It may also be spread via saliva, through mutual grooming or fighting.
 

Is FIP Contagious?

The virus can live on soft surfaces like carpets for up to seven weeks. You can use household disinfectants to clean surfaces, and provide separate litter boxes that you clean often to prevent contamination between at-risk cats and kittens. If you have had a cat that passed away from FIP, it’s recommended to wait at least two months before introducing a new kitten into your home.

Thankfully, FIP is not contagious to other species and will not affect your family members or other pets. Other cats in your home are unlikely to develop FIP unless they are very young and have not already been exposed to the FeCV virus, and even then the virus is not likely to mutate in most cats.
 

Diagnosis And Treatment for Cats with FIP

At this time, there is no single definitive test to diagnose FIP in cats. At first, symptoms like upper respiratory issues and diarrhea may be attributed to parasites or a less serious bacterial or viral infection. Usually, cats are diagnosed when symptoms are persistent and do not respond to antibiotics.

Unfortunately, around 95% of cats diagnosed with FIP will pass away, according to the Merck Veterinary Manual. About half of those will die in fewer than nine days after symptoms first appear. Antiviral medications have shown promise for curing FIP in veterinary research studies, but for now no treatment is approved for use in cats.

If your cat has been diagnosed with FIP, your veterinarian may recommend treatments to suppress the inflammatory and immune system response to extend their lifespan. Early treatment gives FIP cats the best chance at a few extra months of life, but euthanasia may be necessary when your cat’s quality of life has declined.