Demystifying Feline Infectious Peritonitis (FIP) in Cats: An Essential Guide for Pet Owners

Hearing the word “coronavirus” can bring all kinds of thoughts, images, and feelings to mind. First let’s say that, while FIP is a disease that stems from coronaviruses, they are not the same viruses responsible for COVID. So what is FIP? In this comprehensive guide, we'll navigate the complex world of Feline Infectious Peritonitis (FIP), a serious condition that affects cats. Our aim is to empower you with knowledge about FIP, from understanding its causes, symptoms, and potential treatment and management strategies.

Understanding Feline Infectious Peritonitis (FIP) in Cats

What is FIP in Cats?

Feline Infectious Peritonitis, commonly referred to as FIP, is an often fatal immune-mediated disease that affects cats. It's brought on by specific strains of feline coronavirus. While these strains often exist harmlessly in a cat's gastrointestinal tract, about 10% of them mutate, causing the virus to infect the white blood cells and spread throughout the cat’s body.

This mutated virus, known as FIPV, causes the cat's immune system to respond inappropriately, leading to the condition known as FIP. This is a complex disease, any cat that carries the feline enteric coronavirus (FeCV) is potentially at risk of developing FIP but not all FeCV infected cats will go on to develop FIP.

FIP in Cats: How Common Is It?

FIP is a relatively common disease, typically seen more often in environments with a high density of cats, such as multi-cat households, catteries, and shelters. It's also worth noting that the disease often affects young cats, between the ages of 6 months to 2 years, more often than older cats. Additionally, FIP is more common in purebred cats such as Persians, Abyssinians, Bengals, Birmans, Himalayans, Ragdolls, and Rex breeds. However, this doesn't mean that all cats in these environments or categories will develop FIP, it simply means that the mutation from FeCV to FIPV virus is observed more often under these conditions.

Understanding the Different Types of FIP in Cats

Traditionally FIP has been identified as either being in the 'wet' or 'dry' form, depending on the specific symptoms seen in each presentation. The 'wet' or effusive form is characterized by a significant buildup of fluid in the abdomen or chest, whereas the 'dry' or non-effusive form involves the formation of granulomas, or lumps, in various organs and tissues. Despite this historical categorization, FIP can display characteristics of both the wet and the dry form concurrently or in succession.

Identifying Symptoms of FIP in Cats

Initial infection with FeCV generally doesn't manifest any obvious symptoms. Occasionally cats will display mild diarrhea or respiratory symptoms which are usually self-limiting.

The early signs of FIP can be quite non-specific, with cats presenting symptoms such as loss of appetite, weight loss, depression, and fever. As the disease progresses and develops into either the wet or dry form, more specific symptoms may appear. Cats with wet FIP might display abdominal distention or breathing difficulties due to fluid buildup in the abdomen or chest, while cats with dry FIP might exhibit symptoms related to the specific organ or tissue affected by granulomatous formation along with the aforementioned nonspecific signs such as fever, lethargy, and inappetance. Some cats will also display neurologic symptoms such as altered behavior, movements lacking coordination (ataxia), or seizures.

Diagnosing FIP in Cats: A Comprehensive Approach

When it comes to feline infectious peritonitis or any other illness, the clinical examination plays a critical role in the diagnostic process. Your veterinarian will start with a thorough physical examination to observe any overt signs of discomfort or illness in your feline friend. They will also ask about your pet’s health history including recent changes to the pet’s behavior or environment. As discussed, FIP may manifest non-specific symptoms which often overlap with other illnesses. Therefore, your veterinarian will need to rule out other illnesses while narrowing in on an FIP diagnosis.

Investigating FIP: Laboratory Tests and Imaging Techniques

Diagnosing FIP is challenging. However, laboratory tests are often the next step in investigating FIP. Tests called titers are available for showing exposure to FeCV. However, it is important to remember that many cats will encounter FeCV without going on to develop FIP. Therefore, such tests must be looked at along with the rest of the clinical picture to decide the significance of their results. Other pieces of the clinical puzzle include screening blood tests, such as complete blood counts and chemistry panels, and imaging such as ultrasonography and radiography (X-rays).

In wet cases of FIP, where fluid is present, it can be isolated for further analysis. Such fluid analysis looks for the characteristic yellow, highly protein-rich and white blood cell laden properties seen in effusive FIP. Other tests directed toward virus isolation such as immunofluorescence assays, polymerase chain reactions, and immunoperoxidase testing can help but each has its own pitfalls and none are completely accurate.

Treatment and Management of FIP in Cats

Until recently, FIP was considered an untreatable and fatal disease with a majority of cats (95%) passing from the disease itself or humane euthanasia. However, recently there have been new developments and there are possible treatments on the horizon. It is important to note that at the time of this writing, there are no FDA approved medications to treat FIP. It is important to have a consultation with your veterinarian to discuss regulatory issues, sourcing,risks, benefits, and identifying unknowns when considering treatments not approved by the FDA.

Exploring Upcoming Treatment Options for FIP

One new promising medication, that has yet to be FDA approved, is GS-441524. This is an antiviral drug that studies suggest can serve as a potential treatment option for the wet form of FIP. But it's essential to note that there is no data on long-term treatment using this drug nor the efficacy when using it to combat the dry form of FIP; therefore, it is not yet FDA-approved and products available in the market may vary significantly in terms of concentration, purity, and legality in sourcing.

Another related antiviral drug is remdesivir, in fact GS-441524 is a metabolite of the pro-drug remdesivir. Meaning the body breaks remdesivir down into an analogue of GS-441524 (and other molecules).

While these drugs may bring some hope, it's crucial to remember that much is still unknown and neither is approved for use in cats. Always discuss all risks and benefits with your veterinarian before starting any new medications for your cat.

Supportive Care for Cats with FIP

Sadly in the absence of appropriate treatment options, most cats with FIP succumb to the disease. Supportive care can make a world of difference to the cat suffering from FIP by managing symptoms and preserving comfort, in less than 10% of cases it may also extend survival by a few months.

Supportive care can include proper hydration, removal of accumulated fluid, palliative treatment for inflammation and immune reactions, appropriate nutrition, and possibly blood transfusion. Such supportive treatments show the best results with cats who are otherwise doing well, still eating and active.

Prognosis and Life Expectancy After FIP Diagnosis

The prognosis for cats diagnosed with FIP is generally poor, with up to 95% of cats dying within days or weeks of diagnosis. However, with supportive care and attention to comfort, some cats' lives may be prolonged by several months. Every cat is unique and the presentation and progression of FIP can vary. Consult your veterinarian for guidance and help in assessing your cat’s quality of life.

Preventing FIP: Is there a vaccine?

While there is a vaccine for feline enteric coronavirus, there is no vaccine for FIP. The currently available vaccine is labeled for cats 16 weeks of age or older and it is thought that this may be too late as the cat will likely have been exposed to FeCV already. Remember, that places with a high volume of cats such as shelters, catteries, or breeders often have a high incidence of FeCV. For these reasons, the American Association of Feline Practitioners lists the FIP vaccine under “not recommended” at the time of this writing.

Reducing FIP Risk in Multi-cat Environments

Multicat environments pose an increased risk of FIP, primarily due to the ease of transmission of the feline coronavirus amongst cats. High-density environments—like shelters or catteries—can become breeding grounds for the virus, necessitating extra precaution. Implementing practices such as isolating new cats, limiting the number of cats in a single environment, and maintaining a clean environment with enough litter boxes for all cats can curb the spread of the virus.

If one of your cats develops FIP, it is likely that your other cats have already been exposed to the FeCV virus. However, that does not mean they will go on to develop FIP, the mutated virus is not contagious from cat to cat. But because continued exposure to FeCV gives more opportunity for the virus to mutate, you should decrease the presence of FeCV in the environment by frequently cleaning up feces as well as disinfecting bedding, dishes, litter boxes, and the environment with pet friendly cleaners. You should also prevent contact between your FIP positive cat and new cats, especially kittens, who have not been exposed to FeCV.

Regular Vet Check-Ups: Your Best Ally in Pet Care

We cannot stress enough the importance of regular veterinary check-ups. Consistent professional health monitoring can lead to early detection of health issues, including FIP. Although it's not entirely preventable, early detection can provide your cat with a better quality of life and possibly extend their lifespan. Regular check-ups also present an opportunity for ongoing education about your cat's health. Remember, your veterinarian will always be your best ally when it comes to offering professional advice, diagnosing health problems, and guiding you through the options available for managing your pet's health.

Final Thoughts

A diagnosis of Feline Infectious Peritonitis can be challenging to navigate. From understanding the complexities of the disease to grappling with its implications, every step can be daunting. Yet, we firmly believe that with the right informational support, you can make the best decisions for your pet's health. You are not alone in this journey, your veterinarian will help guide you and there are professionals available to help you process through the emotions you may feel as you grieve over the diagnosis.

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The information contained here is for educational purposes and should not be considered veterinary care or advice.

References

• Cornell University College of Veterinary Medicine (2017, Oct 04). Feline Infectious Peritonitis https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-infectious-peritonitis
• Merck Veterinary Manual. Feline Infectious Peritonitis (FIP) - Cat Owners https://www.merckvetmanual.com/cat-owners/disorders-affecting-multiple-body-systems-of-cats/feline-infectious-peritonitis-fip
• José V. Diaz and Roberto Poma. Diagnosis and clinical signs of feline infectious peritonitis in the central nervous system https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2748294/