Cat wrapped in a pink blanket sitting by a window.

Feline infectious peritonitis (FIP) is a viral disease caused by a feline coronavirus that can affect wild and domestic cats worldwide. In many cases, cats infected with coronavirus won’t present with symptoms or become severely ill.1 In fact, 90% of cats in shelters will test positive for prior coronavirus exposure but will never show signs or experience complications.2 However, cats that exhibit symptoms of FIP will often pass away from the disease. 

While FIP is challenging to diagnose, it’s important to know the warning signs of feline infectious peritonitis and ways to minimize the risk of your cat becoming infected. Get started by reading from start to finish or use the links below to navigate the post. 

Note: There are various strains of coronavirus, and feline coronavirus differs from the COVID-19 that affects humans. Feline coronavirus can only be transmitted from cat to cat and doesn’t cause infection in humans.

What Is Feline Infectious Peritonitis (FIP) in Cats?

Feline infectious peritonitis is a fatal disease caused by a feline coronavirus, which is a family of viruses that result in respiratory infections.3 While a large portion of cats can be infected with coronavirus, only a few types mutate into the pathogenic form and cause disease. This can be due to spontaneous mutations within the virus. Feline infectious peritonitis can impact all breeds of cats, regardless of their age or sex.

Feline infectious peritonitis (FIP) is a viral disease caused by strains of the feline coronavirus (FeCV).

How Do Cats Get FIP?

The strain of coronavirus that causes FIP is often transmitted through ingestion, which means a cat usually has to eat something that contains the pathogen. This can occur when cats consume infected feces in litter boxes, share a food or water bowl, or ingest saliva during mutual grooming. In some cases, it can also be spread through inhalation when cats are in close contact or sneeze4

It can also be passed down to kittens from their mother’s placenta, making young kittens more likely to inherit or have the disease. According to Cornell University College of Veterinary Medicine, 70% of cases of FIP occur in cats less than 1 ½ years of age, while 50% occur in cats less than seven months.5

 FIP in cats can be transmitted by ingesting feces, sneezing, mutual grooming, sharing the same food bowl, and close contact with a cat infected with FIP.

Additionally, settings with multiple cats, such as shelters and catteries, can be the perfect breeding ground for feline infectious peritonitis—75% of cases of FIP occur in multi-cat environments.6  If you have several cats, make sure they have enough space to urinate, defecate, eat, and play without overcrowding. Here are a few other ways you can minimize your cat’s risk of developing FIP:

  • Promptly cleaning up feces
  • Isolating cats with FIP
  • Disinfecting their environment 
  • Staying up to date with vaccinations 
  • Keeping litter boxes away from water or food bowls 
  • Vacuum carpets and other areas thoroughly 

The Best Friends Animal Society states that increased stress can increase the chances of a cat developing the disease.7 So, it’s a good idea for cat owners and caretakers to learn how to ease a cat’s anxiety

Certain cats may also be more susceptible to FIP than others.8 For instance, purebred cats, intact males, and specific breeds, including:

  • Abyssinians
  • Bengals
  • Birmans
  • Himalayans
  • Ragdolls
  • Rexes

What Are the Symptoms of FIP in Cats?

Cats with feline infectious peritonitis sometimes won’t show any signs of infection, especially if they have been exposed to feline enteric coronavirus (FeCV)—a type of coronavirus that primarily affects the gastrointestinal tract and hardly causes illness.9 However, when symptoms of FIP in cats are present, the diseases manifest in a wet or dry form, sometimes both:

  • Effusive (wet form)—Effusive FIP occurs when blood vessels are inflamed or damaged, resulting in fluid seeping into the abdomen or chest.10 A build-up of fluid within the abdomen, chest, and heart can cause these affected areas to swell. This excess of fluid may make your cat have a pot-bellied appearance. Further, increased fluid can impact your cat’s lungs, leading to a hard time breathing. One-third of cats will experience difficulty breathing with the wet form of the disease. 
  • Non-effusive (dry form)—As the name implies, there’s no fluid accumulation in the non-effusive form of the disease. Instead, different organs can be affected, such as the liver, kidneys, pancreas, CNS, and eyes, because of inflammatory lesions. In 30% of cases, both the eyes and brain will be affected due to non-effusive FIP.
Symptoms of FIP in cats include diarrhea, vomiting, stunted growth, upper respiratory signs, and weight loss

FIP in cats symptoms may also overlap. This includes:

  • Diarrhea
  • Vomiting
  • Stunted growth
  • Difficulty breathing
  • Weight loss
  • Depression
  • Sneezing
  • Watery eyes in cats
  • Discoloration of the eyes
  • Dazed and confused
  • Fever
  • Unthrifty hair coat

FIP in cats can also cause a feline’s eyes to become cloudy, yellow due to jaundice, or red. It can also significantly impact the nervous system, leading to seizures and behavioral changes. 

cat laying down with a veterinarian checking its pulse with a stethoscope.

How Is FIP in Cats Diagnosed?

Diagnosing FIP cat disease can be challenging because symptoms mirror other similar diseases. For example, excessive fluid in the chest is a common symptom of neoplasia or liver disease.11

To diagnose your cat with FIP, a vet will have to evaluate their medical history, conduct physical exams, and assess lab results for an overview of your cat’s condition. A few changes in your cat’s blood work, alongside notable symptoms, can indicate FIP.12 This includes:

  • Low lymphocytes (a type of white blood cell)
  • High neutrophils (a type of white blood cell)
  • Rise in globulin concentration
  • Increased liver enzymes
  • Anemia
  • Elevated bilirubin
  • Increase in total proteins

Additional tests may have to be taken in order to verify FIP in your feline, such as ultrasonography, fluid sample testing, special FIP blood tests,  and surgical biopsies, which is one of the best ways to confirm a diagnosis.13 During a biopsy, a licensed veterinarian will administer anesthesia to your cat and remove tissues or cells from a specific area of their body. They’ll then analyze it under a microscope. However, some cats may be too sick for this procedure to occur while they’re alive. 

Even though vets can check for coronavirus antibodies, this will only reveal exposure to the virus, whether it’s a new infection or old. However, it may be useful to test for these specific antibodies in multi-cat households where one or more cats were infected before they’re reintroduced to the group. 

Can FIP in Cats Be Treated?

Unfortunately, 95% of cats diagnosed with FIP will die from the disease once symptoms have progressed.14 Cats with FIP can be prescribed medication to reduce inflammation and suppress immune reactions, allowing you to manage their condition. Appropriate medical and supportive care is essential during this time since it can provide relief temporarily and make the experience more comfortable for your cat.

Depending on how advanced your cat’s symptoms are or their condition, euthanasia may be a viable option that can keep them out of pain. A veterinarian can discuss different end-of-life and temporary treatment options so that you can decide what’s best for your feline.

If a cat with FIP is still healthy, meaning they’re eating well, don’t have nervous system problems, or develop secondary infections, the outcome is better. In some cases, treatment can prolong the survival of your cat. However, keep in mind that this is less than a 10% chance. If a cat’s symptoms don’t improve within three days of treatment, they most likely won’t make it. 

While there’s a vaccine available for FIP, it isn’t generally recommended by the American Association of Feline Practitioners and most veterinarians do not offer it.15 This is because the vaccine is available to felines 16 weeks of age or older, and many kittens will develop the disease before this time. The vaccine must also be administered before a cat is exposed to feline coronavirus.

Note that this doesn’t mean you can’t request your cat to receive the vaccination. As a non-core, or optional, vaccine, it’s best to discuss the pros and cons with your veterinarian to decide if it’ll benefit your feline.

With all that said, there’s some hope for cats with FIP. There’s currently two unapproved, experimental antiviral drugs that can allegedly cure cats with the disease.16  According to the American Veterinary Medical Association, treatment has been successful in 25 out of 31 cats. While the two drugs have shown promise, their efficacy and safety still need to be reviewed. For more information, you can look into FIP Warriors17, where you can learn about these new treatment options.

Final Notes

Ultimately, feline infectious peritonitis is fatal, especially if symptoms are present and have advanced. Despite this, there is good news: many cats will remain asymptomatic and will never experience complications from FIP. While you can’t prevent your feline friend from becoming infected, you can minimize their risk by maintaining a sanitary environment. If there are multiple cats in one household or space, make sure there’s ample room for every feline. It’s also essential to keep their stress and anxiety low in settings with many cats. 

At Dutch, we can help you ease your cat’s anxiety with vet telemedicine for pets. Our quick and convenient services make it easy to get your cat evaluated and receive the specialized treatment necessary for a happy and healthy life. Check out Dutch.com to get assistance for your cat’s behavioral issues today.

References

  1. Levy, Julie K., and Staci Hutsell. “Feline Infectious Peritonitis (FIP).” Merck Veterinary Manual, Merck Veterinary Manual, 15 Nov. 2021, https://www.merckvetmanual.com/cat-owners/disorders-affecting-multiple-body-systems-of-cats/feline-infectious-peritonitis-fip.

  2. “Feline Infectious Peritonitis (FIP).” Best Friends Animal Society, https://resources.bestfriends.org/article/feline-infectious-peritonitis-fip.

  3. Levy, Julie K., and Staci Hutsell. “Feline Infectious Peritonitis (FIP).”
  4. “Feline Infectious Peritonitis.” Cornell University College of Veterinary Medicine, 15 June 2021, https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-infectious-peritonitis.

  5. Pesteanu-Somogyi, Loretta D et al. “Prevalence of feline infectious peritonitis in specific cat breeds.” Journal of feline medicine and surgery vol. 8,1 (2006): 1-5. doi:10.1016/j.jfms.2005.04.003

  6. “Feline Infectious Peritonitis (FIP).” Best Friends Animal Society.

  7. Pesteanu-Somogyi, Loretta D et al. “Prevalence of feline infectious peritonitis in specific cat breeds.”
  8. “Feline Infectious Peritonitis.” Cornell University College of Veterinary.
  9. “Feline Infectious Peritonitis (FIP).” International Cat Care, 7 Oct. 2021, https://icatcare.org/advice/feline-infectious-peritonitis-fip/.

  10. “Feline Infectious Peritonitis (FIP).” International Cat Care.

  11. Levy, Julie K., and Staci Hutsell. “Feline Infectious Peritonitis (FIP).”

  12. Stone, Amy, et al. 2020 AAHA/AAFP Feline Vaccination Guidelines*, American Animal Hospital Association, https://www.aaha.org/globalassets/02-guidelines/feline-vaccination-guidlines/resource-center/2020-aahaa-afp-feline-vaccination-guidelines.pdf.

  13. Burns, Katie. “FIP Drugs Continue to Show Promise, While Being Sold on Black Market.” American Veterinary Medical Association, 2 Jan. 2020,  https://www.avma.org/javma-news/2020-01-15/fip-drugs-continue-show-promise-while-being-sold-black-market. .

  14. FIP Warriors, https://fipwarriors.com/