FIP (Feline Infectious Peritonitis) is a fatal disease that affects cats. Still, there is no cure for FIP and it is 100 percent fatal. The disease is caused by a mutation of feline enteric coronavirus (FECV) or simply Feline coronavirus (FCoV). But, according to a recent study, titled “Efficacy of a 3C-like protease inhibitor in treating various forms of acquired feline infectious peritonitis”, published in September 2017, an antiviral compound (GC376 protease inhibitor) has opened the door to targeted antiviral drug therapy and FIP treatment. The compound GC376 was originally synthesized in 2011 while looking for cures for the Norwalk virusNotes 1. It was found to have a broad spectrum of activity against other viruses – including the coronavirus family – one of which is the cause of FIP.

Sarman the orange cat, August 11, 2017
The last healthy photo of Sarman. Taken on August 11, 2017. Just in ten days, he’d get terminally ill.

Last September, I lost my beloved Sarman to FIP (pictured above – it was his last photo when he was still healthy). He died a month after he was diagnosed with this horrible disease. So, If you started searching for a possible FIP treatment on the Internet, and stumbled upon this page, I am really sorry for you. Perhaps your or your family’s cat (or a friend’s, or a relative’s cat) is diagnosed with the disease. I know how do you feel, I know how your heart is broken, how you feel empty and helpless. Because I’ve been there too.

It won’t bring back my lovely orange tabby, Sarman, but if this GC376 thing becomes available as some sort of medicine in the future, I will be very happy. Last summer only, I dug more than ten graves for cats who died of FIP.

According to the study, published in the US National Library of Medicine National Institutes of Health, GC376 was tested on a cohort of client-owned cats with various forms of FIP.

There are two types of FIP: Effusive (wet) and non-effusive (dry). Both types are extremely fatal, but the effusive form is more common (60-70% of all cases are wet) and progresses more rapidly than the non-effusive form. It is also far more deadly (100 percent deadly, unfortunately). Twenty cats from 3.3-82 months of age (mean 10.4 months) with various forms of FIP were accepted into a field trial. Fourteen cats presented with wet or dry-to-wet FIP and six cats presented with dry FIP. GC376 was administered subcutaneously every 12 h at a dose of 15 mg/kg. Cats with neurologic signs were excluded from the study. Nineteen of 20 cats treated with GC376 regained outward health within 2 weeks of initial treatment. However, disease signs recurred 1-7 weeks after primary treatment, and relapses and new cases were ultimately treated for a minimum of 12 weeks. Relapses no longer responsive to treatment occurred in 13 of these 19 cats within 1-7 weeks of initial or repeat treatment(s). The severe neurologic disease occurred in 8/13 cats that failed treatment and five cats had recurrences of abdominal lesions. At the time of writing, seven cats were in disease remission. Five kittens aged 3.3-4.4 months with wet FIP were treated for 12 weeks and have been in disease remission after stopping treatment and at the time of writing for 5-14 months (mean 11.2 months). A sixth kitten was in remission for 10 weeks after 12 weeks of treatment, relapsed, and is responding to the second round of GC376. The seventh was a 6.8-year-old cat with only mesenteric lymph node involvement that went into remission after three relapses that required progressively longer repeat treatments over a 10 month period. Side effects of treatment included transient stinging upon injection and occasional foci of subcutaneous fibrosis and hair loss. There were retarded development and the abnormal eruption of permanent teeth in cats treated before 16-18 weeks of age.

Researchers conclude “GC376 showed promise in treating cats with certain presentations of FIP and has opened the door to targeted antiviral drug therapy”.

Sarman the cat, FIP, September 13, 2017
This photo was taken on September 21 at around 20:00. It was my Sarman’s last photo. In a few hours, he would be dead of FIP. Looking at this photo still hurts… I really hope this compound opens a door to FIP treatment.

Yunjeong Kim, a virologist in the College of Veterinary Medicine, and one of the authors of the study say “The field trial of GC376 was the first antiviral treatment for naturally occurring FIP, and it was designed to address several questions. One of the questions was to find out whether antiviral treatment holds promise in FIP treatment.”

Kim explains: “They were at different stages with various clinical signs and were recruited into the trial. A total of 20 cats received antiviral treatment and seven of those cats are currently in long-term remission. This trial gave us valuable information regarding which patient groups seem to have a better prognosis for long-term remission. Typically, acute wet FIP progresses rapidly and kittens are usually euthanized within weeks of diagnosis. But six out of eight kittens with wet FIP that were admitted into the trial are currently in remission with the longest remission time at one and a half years.”

Other cats in the trial that were chronically ill also quickly improved on antiviral treatment and had a varying duration of clinical remission before many of them succumbed to neurological disease later.

Kim also emphasizes how this was a small study consisting of various patient groups, and said a larger trial focusing on each patient group would be needed to confirm the findings: “From this trial, we learned the answer to the important question: antiviral treatment would be an essential component of effective FIP treatment and early diagnosis/treatment is the key to treatment success.”


  1. Norwalk virus is a common cause of vomiting and diarreal illness each winter and has often been referred to as “stomach flu” or “Winter Vomiting Disease”. Norwalk virus infections have been linked to outbreaks of vomiting and/or diarrhea in institutions such as child-care centres and long term care facilities as well as on cruise ships, camps, schools and households. The Norovirus group were first identified as the cause of a primary school outbreak of vomiting/diarrhea in Norwalk, Ohio during the early 1970’s.


M. Özgür Nevres

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  1. Hi
    I’m Shaik Ahmed from
    Hyderabad India
    My kitten is not active and weight loss, fever temperature is 99, seating one place only

    FIP diseases have my kitten
    What to do my kitten now please share me details.

    1. Hi Ahmed,
      Sorry for your kitten.
      I am really, really sorry, but FIP is still incurable. This treatment is still in the testing phase and not available for the world. All you can do is making the cat as comfortable as possible. You can also contact your vet but s/he cannot do much, either.

  2. I found out a few days ago my family kitten was diagnosed with FIP. Didn’t think much of it until I saw her for the first time since we found out today. It hurts knowing she cant be healed and we’re going to lose her. It hurts more knowing our cats brother will meow in vain looking for her when shes gone and my younger sister who loves that cat with everything she has will have to lose such a beloved pet.
    Its been a rough day.

  3. Hello,

    I found your website while searching about the FIP. I think you’re Turkish and so am I 🙂 That’s great that you’ve made such an informational blog about cats. We have been feeding stray cats and one of them looked very sick today. I can understand when an animal is sick from their eyes. I guess I have a gift. So I called my vet and then poor kitten is diagnosed with FIP. He said there’s no cure but I don’t believe in that. Every disease has a cure which is actually in plants. I put turmeric in her water and we took her in for now. I believe in plant based meds so will try coconut oil and turmeric as a start. She will stay in our closed balcony where she can feel warm and safe. Stress makes their immune system weak which causes this awful disease. I’ve been reading about treatments and got this clinical treatment which you wrote about. What a shame that it’s not available for us…Chemical structure of this vaccine is 10% ethanol and 90% polyethylene glycol 400 which is found in some eye drops. I am planning to vaccinate her with this mixture every 12 hrs…I hope it works. Better to try something than sit and wait…

    1. Hallo, i am from Germany and my beloved cat has fip too. Unfortunately we don’t have any medicine against this terrible deseas too… do you achieve any sucess with ur treatment. Would be thankfull for your answet

      1. Hi,
        unfortunately, this research is still in the test phase and not available publicly. There’s still no cure for FIP. Reaşşy, really sorry. I wish there’s a cure since I lost a few cats to this horrible disease.

    2. Hi Reign,

      I am interested to learn how the cat responded to the turmeric treatment?

      And you fed the cat eye drops, is that you’re saying at the end of your comment?

  4. I lost a newly adopted kitten just a week after we brought her home to FIP last September, and just lost my big baby Gabriel yesterday to this horrid disease. The look in your Sarman’s eyes in his last photo looks so familar it hurts. It’s such a horrific disease, and I am praying so hard for a treatment so that less cats are lost to this. Hopefully Sartan has found Gabe on the other side of the rainbow bridge and his showing him around. 🙂

  5. So sorry to hear of everyone’s experiences with FIP. We lost our beloved one year old, Milo, last Saturday (6/22)to this horrible disease. Milo was always special – very talkative, alert and just super funny! One thing about Milo, though – that brought me here looking for information, is that he was always hungry! Always ready for that next meal, even if he had just finished eating. In reading other stories about FIP, i am coming to find out that extreme hunger is an early symptom….I don’t think that it is just coincidental that all of these animals share this trait. It is just so sad! Our other cat, one year old Carti – was Milo’s best friend. Where you found one of them – the other was always nearby. They would do everything together – sleep, eat, watch out the window, clean each other – it was so endearing. Hoping there will be some type of cure soon!

  6. I also lost 2 kittens to FIP but please know that the cure IS available. GS441 is not yet approved by the FDA but there are several manufacturers in China whose products have been lab tested and confirmed to be effective. It just became available in March 2019 and there are already 100 cats who have been clinically cured, with roughly 1000 more cats currently treating. Join FIP Warriors Using GS group on FB or read more about the treatment options at FIP IS NO LONGER A DEATH SENTENCE!

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