It can be extremely difficult to receive news that your little one is sick and even more difficult if you’ve never heard of the disease/illness and are receiving the information for the first time. For that reason, I thought I would start a newer segment on the site where I take the time to break down the most common cat illnesses, what you should look for, what the treatments are and a recap of what your vet may have told you while your cat was being diagnosed.
WHAT IS FELINE INFECTIOUS PERITONITIS?
Feline Infectious Peritonitis (which will be referred to as FIP for the remainder of this article) is considered a progressive disease. Progressive diseases are classified as diseases that can worsen or develop elsewhere if left untreated and may lead to death.
FIP, in particular, is usually caused by a coronavirus (a virus that usually begins in the nose, sinuses, or upper throat) and is usually treatable in early stages.
Although rare, coronaviruses may mutate into a more serious form which ends up weakening your cat’s immune system. If the coronavirus is left untreated and worsens it spreads through the white blood cells and may lead to death.
WHO IS AT THE GREATEST RISK OF FIP?
Cats under the age of 3 are at the highest risk of FIP. This is due to the fact that they have not had enough time to develop strong enough immune systems.
ARE THERE ANY OTHER DISEASES OR INFECTIONS ASSOCIATED WITH FIP?
Not necessarily associated, however, cats who have lower tolerances or a weakened immune system tend to be at a higher risk. This is why cats who are diagnosed with feline immunodeficiency virus (FIV) or feline leukemia (FeLV) are usually watched more closely.
ONE OF MY CATS HAS FIP, WILL MY OTHER CATS GET IT?
While your cats are at a higher risk of developing FIP, not all cats who are exposed to FIP actually develop the disease. It’s actually said that the majority of cats who are exposed to the illness do not actually get sick.
HOW IS FIP TRANSMITTED?
It is said that FIP is spread through fecal matter, although this belief is not 100%. This being the case, it is believed that FIP is not highly contagious.
I HEARD THERE ARE MULTIPLE FORMS OF FIP, IS THIS TRUE?
You would be correct. There are two known forms of FIP. There is an acute form (which means that it has a rapid onset), and a chronic form.
The acute form (effusive) of FIP is often referred to as “wet” FIP, this form comes very suddenly and usually comes with a buildup of fluid in your cat’s abdomen and chest cavity. You may also notice your cat having some difficulty breathing.
The chronic form (non-effusive) of FIP is often referred to as “dry” FIP, this is because there is no fluid buildup. Instead, your cat may have lesions develop on their organs. A common side effect of the lesions is seizures or paralysis. If extreme, your cat may also begin to lose weight, become lethargic or develop kidney or liver problems.
The majority of cats will be diagnosed with the acute form of FIP.
CAN YOU LIST OUT ALL OF THE SYMPTOMS FOR ME?
Common in both types
Fevers that aren’t responsive to antibiotics
Anorexia
Weight Loss
Lethargy
Common in “Wet” FIP
A build-up of fluid in the abdominal cavity
A build-up of fluid in the chest cavity
Laboured Breathing (most common when cats have fluid in the chest)
Common in “Dry” FIP
Inflammations/Granulomas on organs
Kidney Failure
Excessive Thirst
Excessive Urination
Vomiting
Weightloss
Jaundice
Neurological Damage

HOW DO VETS DIAGNOSE FIP?
FIP is actually fairly difficult to diagnose, however, vets will commonly run blood tests to see whether or not your cat has been exposed to the feline coronavirus. Your vet may also run some of the following tests (dependant on your cat’s symptoms):
An abdominal x-ray to see whether or not there is fluid build-up
- A microscopic examination of the fluid extracted
Tests for the Vital Organs including heart, liver, pancreas, kidney as well as a sugar level test
A Blood Test
Electrolyte test
Test for FeLV or FIV
A FIP Virus PCR test to see if your cat has any signs of mutations
WHY IS IT SO HARD TO DIAGNOSE?
The simple answer is, often different ailments look exactly the same. There’s no way to really diagnose whether or not your cat has the FIP coronavirus or the harmless intestinal coronavirus (which is usually just accompanied with diarrhea). Even though a test shows positive, it does not mean that it is correct in this case, however negative tests usually prove the fact that your cat does not have FIP (although again, there have been cases where this is untrue.)
IS ONE TYPE MORE DIFFICULT TO DIAGNOSE THAN THE OTHER?
Absolutely. The “dry” form of FIP is a lot more difficult to diagnose and it often requires a biopsy of the affected organs.
WHAT ARE SOME OF THE TREATMENTS?
At the moment there is no treatment or cure for FIP itself. There are treatments for the infections caused by the disease and will help make sure your cat lives a longer and healthier life. Some treatments include:
Fluid Treatments for Dehydration
Antibiotics for Infections
Procedures to remove excess fluid
Anti-Inflammatories (glucocorticoids)
Nutritional Support
IS THERE ANY ADVICE FOR PREVENTION?
Absolutely, make sure that you keep your cat’s litter box, water bowl and food bowl very clean. Also, make sure to keep your cat indoors if you are afraid that cats in the area have this disease. There is a vaccine that was developed to prevent FIP, however, it is very controversial. This is due to the fact that some studies have shown that it works effectively, while others show that it offers little to no benefit. I would highly recommend speaking to your vet thoroughly about the vaccine before accepting to allow your cat to receive it. I will do my best to update this article as more studies are conducted.
STATISTICS
Unfortunately, the statistics are fairly grim. Over 95% of cats who have FIP will be in a fatal condition, although in milder cases cats with the “dry” form of FIP can receive treatments to help prolong their life. Cats who have the “wet” version of this disease tend to have a 2-month life expectancy, however, let the next statistics calm you. FIP is very uncommon and in households that have one or two cats, the mortality rate is about 1 in 5000. A more specific number is 5-10% of cats who have been infected by the disease actually get to the stage of “clinical FIP.” So again, the chances are fairly low.
CONCLUSION
While it can be disheartening to know that FIP is uncurable, it does not have to be a death sentence for your cat. There are a number of treatments that can help extend your cat’s life as well raise the quality of their life. I would take my cat to the vet immediately if you are worried about them or ask lots of questions at your next regular vet visit.