Feline infectious peritonitis (FIP) is a complex disease. It’s something all cat parents should know a little about because it’s not just serious, it’s often fatal. The good news is that in the last few years there have been some remarkable developments in treating FIP.

How can this disease affect your cat? More importantly, how can you keep them from being exposed? We’re covering all the basics.

Understanding Feline Infectious Peritonitis (FIP)

FIP can be a confusing disease even for veterinary professionals. There is a feline enteric coronavirus and it can mutate. FIP is caused by a common virus that can rarely mutate and cause serious disease when it does. The disease is a result of an intense inflammatory response by the immune system causing the signs noted below.

What Cats Are Most at Risk for FIP?

This disease is found worldwide and cats of all ages can be affected, but it’s most common in cats under two years of age. Kittens between four and 12 months of age are most susceptible¹.

FIP seems more common in:

• Cats living in multi-cat households or shelters

• Stress (due to re-homing, recent surgery, or have other infections)

• Intact cats (those who are not spayed or neutered)²

• Purebred cats, including Himalayans, Ragdolls, Abyssinians, Rexes, Bengals, and Birmans²

It’s important to know that there is no evidence that feline coronavirus or FIPV can be passed to humans from infected cats². It’s also important to know that just because a cat is infected doesn’t mean they will show symptoms. They can, however, shed the virus, putting other cats at risk. We’ll talk more about this later in the article.

What Are the Signs of FIP?

The initial symptoms of FIP can be vague and similar to other diseases.

Signs include:

• Fluctuating fever
• Lethargy
• Depression
• Listlessness
• Decrease or loss of appetite
• Weight loss

Following a period of several days to months, other symptoms develop.

If a cat has the ‘wet’ form, fluid will accumulate in the abdominal and/or chest cavities. The resulting symptoms, which usually develop rapidly, are abdominal distension (swollen belly) and/or difficulty breathing.

If a cat develops the ‘dry’ form, severe inflammation occurs in one or more organs of the body (eyes, brain, liver, intestines, kidneys, etc.), which can lead to a variety of symptoms. In cases where inflammation affects the eye, the only symptoms are often related to the eye. If the brain is affected by inflammation, it can cause neurologic symptoms (seizures, abnormal gait, and abnormal behavior).

How Do Cats Get FIP?

As mentioned, FIP results from a mutation of the feline enteric coronavirus. Cats become infected with the virus through oral contact with infected poop or saliva, likely at a very young age. The virus can also be spread on clothing or objects within a few hours of contact with an infected cat.

The virus can remain inactive in a cat’s body for months or years before they develop any symptoms, and healthy cats can be carriers and shed the more harmful strain but never show symptoms. In fact, the virus is shed in the poop of about one-third of cats¹. They normally only shed the virus for a few months, but some shed it continuously for life. Cats exposed to virus-containing poop can become infected via the mouth and nose if they eat, lick, sniff, or rub their mouth on something contaminated.

Many cats do not develop FIP even when they are known to be infected with the FIP-causing strain of feline enteric coronavirus. There is no way to predict why one cat will develop FIP and another won’t. Only a minority of cats infected with the feline coronavirus will develop FIP.

Is FIP Contagious?

Feline coronavirus, before mutation, is quite contagious. Infected cats pass it in their poop and saliva, and non-infected cats become infected if they come into contact with contaminated poop via their mouth or nose. However, it is not believed that FIPV, the mutated form of the feline enteric coronavirus, or FIP, the advanced form of infection, is contagious².

How Is FIP Treated?

This is a progressive disease, currently without a cure. Once it has progressed to the point of FIP from feline enteric coronavirus and FIPV, it is almost always fatal. However, supportive care and medications can potentially extend and improve the quality of a cat’s life.

Recently, there have been some promising developments regarding the treatment of this disease. Research at the University of California, Davis, has shown that some newer human anti-viral drugs may be effective. Additionally, there has been investigation into other experimental drugs that, so far, have shown a positive response rate of 80%, which makes researchers optimistic³. However, there are no commercially available or FDA-approved therapies, but these cases are usually treated with steroids if they are treated at all. Steroids and supportive care like oxygen or thoracocentesis are accessible options for most doctors to use. Although this isn’t the first option, considering a humane euthanasia process can provide a compassionate option for some cases of FIP that have gone too far.

How Can You Prevent FIP?

FIP can only be prevented by keeping cats safe from feline enteric coronavirus. This poses a significant challenge because it’s widespread and especially prevalent in multi-cat households and shelters.

Unfortunately, preventing the exposure to the virus or the mutation is challenging. While there is a vaccine for FIP, it’s not generally recommended because it has limited utility. You should work with your veterinarian to develop the best plan for your kitten. Most kittens are infected with feline enteric coronavirus well before the vaccine can be administered at 16 weeks of age. Additionally, AAFP feline vaccination guidelines say that there is insufficient evidence that the FIP vaccine provides clinically relevant protection³.

The best way to protect cats is to keep them as healthy as possible.

• Feed a high-quality, well-balanced diet.
• Maintain an ideal body weight.
• Provide routine veterinary care.
• Keep their vaccines current.
• Maintain good dental hygiene.
• Have an adequate number of litter boxes, especially in multi-cat households, to lessen exposure to other cat’s poop.
• Keep litter boxes clean and away from food and water dishes.
• New cats in a home should be quarantined and monitored for any signs of disease.
• Regularly clean and disinfect any areas the cats have access to, in order to kill viruses.