Sarman the orange cat, August 11, 2017

FIP Treatment – A Promising Research

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.

Last September, I lost my beloved Sarman to FIP (pictured above – it was his last photo when he was still healthy). He died in 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 future, I will be very happy. Last summer only, I dug more than ten graves for cats died of FIP.

According to the study, published in 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). 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 a 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, virologist in the College of Veterinary Medicine, and one of the authors of the study, says “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 a 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 varying duration of clinical remission before many them succumb 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.


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