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Feline Infectious Peritonitis (FIP)

What is Feline Infectious Peritonitis?

Feline Infectious Peritonitis is a fatal viral infection of domestic and wild cats caused by a specific strain of virus called feline coronavirus. Since it produces alpha coronaviruses in cats, it differs from SARS-Cov-2 coronavirus, which produces COVID-19, a beta alphavirus in humans. FCoV is found in both domestically kept and outdoor cats.  Infection rate increases dramatically in multi-litter household when compared to single cat households.

Although Feline coronavirus (FCoV) causes only mild diarrhoea in cats, its mutated strain can lead to serious illness that can lead to death in cats. About 10% of infected cats will develop an infection known as feline infectious peritonitis virus (FIPV) that can spread throughout their bodies. When it becomes progressive it starts involving the kidneys, abdomen, and brain.

What are the Clinical Signs of FIP?

Symptoms of feline infectious peritonitis are diverse and can make the clinical diagnosis based on symptoms
pretty hard. At the start, some vague symptoms are common. These include fluctuating fever, energy loss, and inappetence. After some time, cats can present with ‘dry’ or ‘non-effusive’ disease or ‘wet’ or ‘effusive’ disease.

Dry or non-effusive FIP

It mainly causes inflammatory lesions around the blood vessels affecting the kidneys, liver, lungs, brain, and skin. The cats with the dry form of FIP can show the following clinical signs.

  • Seizures

  • Uncoordinated body movement

  • Excessive thirst and urination

  • Weight loss

  • Jaundice

  • Vomiting

Wet or effusive FIP

In Wet FIP, inflammatory reactions affect the blood vessels causing vasculitis and fluid leakage from the blood into the chest and abdominal cavity. As a result, a large amount of fluid accumulates in the abdomen and chest, causing a pot-bellied appearance and difficulty breathing.

How can FIP be Diagnosed?

Symptoms of FIP are wide yet vague which makes it difficult to diagnose. Also, your veterinarian can not diagnose it based on only one blood test. Following factors can make the diagnosis easy if your cat:

  • Shows clinical signs of FIP

  • Falls in the high-risk groups (e.g., colony cats, colony cats, etc.)

  • Presents with yellowing of the eyes and gums

Based on laboratory tests, a cat affected by FIP can have:

  • Lymphopenia or decrease in the number of white blood cells

  • Neutrophilia or an increase in the number of neutrophils

  • Deficiency of blood

  • Increased concentration of proteins

  • High levels of liver enzymes and bilirubin

Besides, there are many other tests that can confirm its diagnosis. A few of them are:

  • X-ray and Ultrasound

  • Immunoperoxidase test

  • Polymerase chain reaction technology

  • Biopsy

FIP Treatment Options

Despite advances in medical technology, FIP remains a challenge for veterinary professionals. However, recent research completed by a team of animal virological researchers at the University of California Davis has discovered that GS-441524, an antiviral drug use to treat human viral infections can be effective treating feline infectious peritonitis. 

Link to research paper: HERE.
GS-441524 drug is not FDA approved for FIP treatment at the time of this writing.  Its high success rates in treating feline infectious peritonitis gives hope to cat owners and veterinaries from around the world.  In the absence of legitimate supplier, black market suppliers have sprung up in every region of the world to provide cat owners access to GS-441524  Since the official publication of the clinical study using GS-441524 for the treatment of feline infectious peritonitis, according to various FIP focused website and self help groups across the internet, a combined estimate put the number of successful treatments in the hundreds of thousands across the globe.  The results in real world clinical applications seemed to have validated the published results by UC Davis researchers.
Some supportive treatments that are effective against FIV include blood transfusion and drainage of accumulated fluid from the body, B12 vitamin injections and oral dietary supplements. 

Prevention of FIP

You might be wondering- is there a vaccine for cat FIP? Yes, it is available. But the American Association of Feline Practitioners Feline Vaccine Advisory Panel has not recommended this vaccine. However, it is safe and you need to consult your veterinarian regarding this vaccine. You can take the following precautionary measures to prevent FIP.

  • Maintain the hygiene of cats and their litter boxes

  • Prevent overcrowding of cats in your space

  • Keep the cats healthy


Feline infectious peritonitis is an infection in cats caused by a feline coronavirus. Its symptoms are varied and complex, but it commonly presents in dry form or wet form. Your veterinarian can make the diagnosis based on clinical signs and various laboratory tests. GS-441524 is the most promising drug to treat FIP with success rate ranging from 80-95%. The best way is to prevent this disease by taking precautionary measures including avoid exposure to other cats, periodically disinfect areas frequented by cats such as litter boxes, feeding bowls, play pins, cages and pet boxes, Keep only one cat per household, and include feline infectious peritonitis vaccination as part of core vaccination program for all your cats. 

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