1. Good news: Bova Compounding now has an oral formulation of GS-441524 which will make dosing easier and safer than pilling.
2. Not so good news: GS-441524 adverse effect. The Minnesota Urolith Center has discovered bladder stones formed from GS-441524: this side effect is another reason for using this antiviral drug for as short a duration as required to cure FIP. Cure (as opposed to remission) from FIP can be ascertained by two consecutive normal AGP tests a week apart. SAA level return to within normal levels may also be predictive of full FIP recovery, but has not yet been published.
Many thanks to Dominik Mirowski for alerting me to the Minnesota report.
Note: this section is intended for veterinary surgeons only and should NOT be used by cat guardians to attempt to treat cats themselves. However, before leaving the page, guardians please download the following to take to your veterinary surgeons:
FIP diagnosis algorithm (this will open in a new window)
Note - these downloads should open in a new window and in some browsers will simply automatically download.
Click here for printer friendly version (i.e. black writing on white background) (this version is still the old page: until that is updated, you'd be better with the FIP treatment summary which is a printable pdf giving drugs and doses).
FIP is now a curable condition: but prevention is better than cure!
When I first came to Feline Infectious Peritonitis (FIP) research, FIP was regarded as an incurable condition. However, with the introduction of feline interferon and more recently GS-441524, the nucleoside analogue, we now have hope for more than remission of weeks to months: we have hope of complete recovery for some cats, especially those diagnosed in early infection. However, more work requires to be done so that an affordable treatment protocol can be established for people whose cats are not insured. Therefore the emphasis must still be on totally preventing cats ever developing FIP in the first place, and on accurate diagnosis, so that cats with non-FIP conditions are not needlessly euthanased.
This webpage represents only the personal opinions of the author, not all opinion leaders agree with me.
Disclaimer: this website and webpage are for information purposes only, I accept no responsibility for how you decide to use this information.
Remember that many treatments listed here would be off label and that you must inform your client of this fact and have your client sign your practice's legal disclaimer form.
Updates on treatment will appear in the English version of the website before the translated pages.
1. DOUBLE CHECK THE DIAGNOSIS: 40% of cats diagnosed with FIP actually have some other disease
To see me working through FIP diagnosis algorithm on a real life case, watch "Does Pancho Have FIP?" or Does Tommy Have FIP? (These films will count towards your Continuing Professional Development /Veterinary Continuing Education.) Subscribe to my YouTube, Bitchute, and Rumble channels to see new cases when they are uploaded. Also see the FIP diagnosis webpages.
Please watch my film: "Why did GS-441524 not cure this cat?" on any of the following platforms:
You can only be really confident of an FIP diagnosis if you have a positive FCoV RT-PCR result on the effusion of a wet FIP case, or a mesenteric lymph node (MLN) fine needle aspirate (FNA) or aqueous humour in a non-effusive FIP case. Note that cats without FIP can have viral RNA (i.e. a positive RT-PCR result) in their CSF: that is NOT diagnostic of FIP.
Do NOT send blood samples for FCoV RT-PCR testing, even if the laboratory asks for that sample because you are more likely to get a negative result even if the cat has FIP: send either effusion of MLN FNA.
The beauty of altering nutrition immediately is that it will help in any condition, not just FIP—and it is safe. If you have read The China Study, watched Forks Over Knives, or heard Dr Michael Greger’s famous top human killer diseases lecture, you will already be familiar with the enormous impact diet has on preventing, and even curing, the majority of causes of human deaths - the situation in cats and dogs may well be similar.
It is my opinion that feeding as varied and natural a diet as possible to cats with FCoV infection and FIP is essential: avoiding highly processed, pro-inflammatory grain-based commercial foods (even the expensive so-called “veterinary” diets are usually cereal based).
Unlike humans, arginine is an essential amino acid in the cat (Morris & Rogers, 1978): this is why they are obligate carnivores. Arginine is essential not only for the urea cycle but also for the normal functioning of monocytes and endothelial cells.
In the following video, I explain arginine and the urea cycle of the cat:
In the video below (called NEVER give L-lysine to a cat with FIP), I explain why the health of the host's monocyte (i.e. immune system) is actually more important than the virulence of the feline coronavirus infecting it (which explains why some cats develop FIP and other do not, even when exposed to the same amount of the same laboratory strain of FCoV). I also explain the role of arginine in macrophage switching and why, if arginine is limited in the cat, it'll be used for the urea cycle rather than for the immune system.
To see an animation of feline coronavirus infecting a monocyte/macrophage, and wet FIP developing, visit: http://www.youtube.com/watch?v=6RyI2LI9R9Q
Give real meat daily to augment arginine levels: even just a tablespoonful a day will make a difference to FCoV infected cats. It is important that the meat or liver come from free range animals because they will have eaten grass which is rich in omega 3. Alternatively, regularly use commercially available real meat based cat foods e.g. Applaws (MPM products, available from the Zooplus website in Europe); Almo Nature Cat Food.
Increase the anti-inflammatory omega 3 fatty acid content of the cat’s diet (i.e. add sardines, pilchards, salmon, mackerel twice a wk for 6 weeks). Both Applaws and Almo Nature have canned food including real fish. However remember the risk of hypervitaminosis A (excessive laying down of bone at the joints) so be wary of feeding too much real fish – reassess the situation after 6 weeks.
Remember to instruct the cat’s guardian in a gradual changeover of the food: to change it over a period of weeks otherwise the cat will wolf down the new food for a few days, then get sick of it and never touch it again! The way to introduce a new food is to give it for one meal, then go back to the customary diet for the next few meals, then give a little of the new food again, and so on, gradually increasing the frequency of the new foods, until giving a different food every meal becomes the norm for the cat. To introduce new foods gradually properly will take at least a month.
FCoV associated diarrhoea is helped by chicken and pumpkin cat food and Protexin Pro-kolin enterogenic probiotics
My FIP treatment protocol at time of writing (2023) is as follows: GS-441524 pills or potion until two consecutive normal AGP results at least one week apart, followed by oral Virbagen Omega.
Previously my protocol was feline interferon omega (s/c for effusive FIP, oral in non-effusive FIP); meloxicam, Vitamin B12 (Cobalaplex pills by Protexin: half every day or a whole capsule every other day) and other treatments tailored to each individual cat: these will keep the cat going until you are able to obtain a specific anti-coronavirus drug.
The best anti-viral drugs to treat FIP are GS-441524 pills rather than injections (Krentz et al, 2021) because the injections are very painful and destroy the patient / human bond. Some cats develop weeping, painful lesions at the site of injection (Pedersen et al, 2019). In addition, the injections are less effective than pills and do not reliably stop FCoV shedding in the faeces. I am now being consulted about cats who are in relapse following a 12 week course of FIP treatment: these cats were almost always only treated with injections, rather than pill forms, or their treatment was begun with an injectable anti-viral. Liver support using S-adenosyl-L-methionine is essential for longer term use with nucleoside analogue antiviral compounds. Once we have two consecutive normal AGP results at least one week apart, we stop the oral GS-441524 and go onto low dose oral Virbagen Omega until the cat's FCoV antibody titre drops significantly (Addie et al, 2022). In-contact cats are tested for FCoV shedding and we stop them shedding virus to prevent re-infection of the patient. Details of this protocol can be found below.
A major hurdle in some countries is that none of the anti-coronavirus treatments for FIP is yet approved, therefore an alternative protocol needs to be found.
GS-441524 injections: not recommended
Interferon / Virbagen Omega
GS-441524 is an adenosine nucleoside analogue that terminates the RNA chain of viral RNA-dependent RNA polymerase. In the UK and Australia, veterinary surgeons can obtain VMD and Australian Pesticides and Veterinary Medicines Authority (APVMA) approved GS-441524 pills from Bova. (Cat guardians - you are not allowed to buy these pills directly, your vet will supply them for you.)
I'm sorry I don't have a contact for Bova Australia, but this is their website: https://bovavet.com.au/
Bova GS-441524 pills contain about 50mg of active ingredient: the pills are scored and can easily be broken into halves or quarters.
Dose: 20mg / kg bodyweight per day Bova GS-441524 pills for cats with neurological or ocular signs and 10mg/kg for cats without neurological / ocular signs.
Note that this dose is double that used in Mutian X studies (Addie et al, 2020; Krentz et al, 2021): this is because two independent analyses of Mutian pills allege that Mutian X contains more of the GS-441524 component than is claimed by the manufacturers (Addie et al, 2023). I have to admit that I have not yet supervised treatment of a cat with FIP using Bova pills therefore I am extrapolating dosages from what we know about treatment with Mutian X pills.
In my protocol, all cats with FIP have the double dose of pills for about 10-14 days in order to clear virus from the brain to avoid neurological relapses, then in effusive cases and non-effusive cases with no neurological or intra-ocular signs, the dose reduces to one Mutian 100 per kg per day (for Mutian X) or 10mg/kg q24h for Bova GS-441524 in divided doses and followed by food to slow the transit through the gut and maximise absorption.
PILLING: please warn the cat's guardian about the risks of oesophagitis following pilling, and that it's important to follow a pill with some food or drink to ensure it is properly washed down into the stomach and doesn't lodge in the oesophagus. Another reason for giving the antiviral with food is because we want the active antiviral to be absorbed and not simply pass through the intestinal tract rapidly, so giving with food delays the passage through the gut. For cats who are difficult to pill, try a pill popper; wrapping the pill in tuna or salmon pate; or using Royal Canin's Pill AssistTM. If the cat tends to vomit with the antiviral, then give a little food before pilling.
Please see the section on supplements and use S-adenosyl-L-methionine (SAMe, e.g. Denamarin, Hepatosyl) to protect the liver when using GS-441524.
Be aware that high doses of nucleoside analogue may damage the kidneys therefore monitor SDMA and reduce dosage to 5mg active ingredient per bodyweight q24 hrs (in divided doses) as soon as clinical signs resolve.
Remember that this treatment would be off label and that you may want to have your client sign your practice's legal disclaimer form. Check with your own regulatory body for advice about the legality of its use in your own country.
In China, Mutian Xraphconn (Mutian X or simply Mutian), which contains GS-441524 (Krentz et al, 2021), is available as capsules or tablets: the Mutian 200 pill is said to contain 10mg of active ingredient. Their website is www.mutianstore.com.
GS-441524 injections: NOT RECOMMENDED, use oral treatment preferably
In my online referral practice, I am increasingly seeing cats who have relapsed following an 84 day course of GS-441524: these cats have usually been treated with an injectable form of GS, or they began their treatment with an injectable form of GS-441524. The reason these cats are more likely to relapse is because the drug does not adequately penetrate the gut which is where the virus maximally replicates, and so some virus escapes, crosses the blood-brain barrier where it causes a build up of CSF (i.e. hydrocephalus) which present clinically as neurological signs. Please download and read my 10 Rules to Prevent FIP Relapses.
GS-441524 is the metabolite of Remdesivir (Gilead Sciences, USA). There were promising results with GS-441524 in vitro and in one in vivo experimental study, Murphy et al., 2018 and the eagerly awaited clinical trial was published in 2019. (Pedersen et al, 2019) Thirty-one cats were enrolled in the field study: 17 of 20 with effusive FIP, 2 developed neurological signs and were euthanased and one died due to cardiomyopathy. Eleven other cats were treated with GS-441524 injections: 4 died shortly after treatment commenced, and of the remaining cats, 3 with presumptive non-effusive FIP recovered as did 4 dry-to-wet cases. Thus of the 31 cats treated, 24 survived by time of writing up the paper.
Dose: GS-441524 injection treatment at a dosage of 4 mg/kg SC sid for up to 12 weeks (until the acute phase protein level is normal for two consecutive weeks: see Addie et al, 2022), repeating the course if clinical signs recur. The dose can be increased to 5mg/kg Murphy et al., 2018 in severe cases and 10mg/kg in neurological (Dickinson et al, 2020) or ocular cases.
I do not recommend using GS-441524 or Remdesivir (Veklury) injections (unless the cat is absolutely impossible to pill) for the following reasons:
Giving GS-441524 pills targets FCoV where it replicates: in the intestine, whereas if you inject it, penetration to the inside of the intestine will presumably be less (Addie et al, 2022). Drug-resistant SARS-CoV2 mutants have arisen because of poor penetration of the lung, the site where SARS-CoV2 mainly replicates.
Molnupiravir is available from Bova Specials in Australia and so will hopefully be available in other countries.
Dose for treating wet FIP and by implication for stopping FCoV shedding: 20 mg/kg/day (i.e. 10 mg/kg twice daily) (but note that I recommend beginning all FIP treatment with 10-14 days of a neurological dose to clear the brain of virus: see my 10 Rules to Prevent Relapses)
Monitoring cats on GS-441524 or molnupiravir treatment
Stop the GS-441524 pills when alpha-1 acid glycoprotein (AGP) levels consistently return to normal (Addie et al, 2022) and put the cat onto 100,000 units of Virbagen Omega per cat sid per os instead. The best indicator that FCoV no longer exists within the body is when the FCoV antibody titre reduces significantly (preferably to under 1:10), using a sensitive FCoV antibody test: see the FCoV antibody page for which test is best. However, the FCoV antibody titre is the slowest parameter to return to normal (i.e. zero) when a cat recovers from FIP.
Monitor weight to assess response to treatment: see my video www.bitchute.com/video/Vr3wkoW8SkrP/.
Mutian X pills are effective at stopping FCoV shedding: the dose for clearing FCoV infection is 4mg/kg for five to seven days (minimum 4 days: see Addie et al, 2020a). Although there is no published report showing efficacy of Bova GS-441524 pills for clearing FCoV infection, one of my colleagues informs me that it does: the dose is 10mg/kg for 5-7 days. I am investigating another treatment for stopping FCoV shedding, but have not got enough evidence yet to report upon it.
Skywise had been blind: his sight was restored and he is alive and well almost two years following Mutian X treatment.
This is Bea whose effusive FIP was treated with Mutian pills:
Watch this space for updates on antivirals, and follow me on:
MeWe (a privacy honouring alternative to Facebook): www.mewe.com/i/catvirus1
Bastyon (a free speech alternative to Twitter)
Seek advice from your own veterinary body about using anti-coronavirus antivirals in your country. Disclaimer: I am not a lawyer, I do NOT know if this is legal, and I am not responsible for your choices about whether or not to use it: you do so at your own risk.
A report of Dr Pedersen’s presentation can be found here: www.vin.com/apputil/Project/DefaultAdv1.aspx?pId=99&catId=102069&id=8124390.
Watch Dr Pedersen’s SOCK website for news of updates and new clinical trials. www.sockfip.org
There is an article about a cat called Luna, who was in Dr Pedersen's GS 441524 treatment trial here: https://pethelpful.com/cats/Hope-for-Feline-Infectious-Peritonitis-aka-FIP-Lunas-Story
GS-441524 not working in your patient?
In my experience, the main reason for this is that the cat is not, in fact, suffering from FIP: 40% of the cats referred to me - usually from referral practices - have had some disease other than FIP. Please download my 10 Rules for Preventing FIP Relapses to obtain further insight into the possible reasons.
To obtain a consultation with me, please visit the www.catvirus.com home page.
GC376 is a 3C-like protease inhibitor antiviral drug, not currently commercially available so far as I know. In my opinion, it has been eclipsed by GS-441524 (see above). In the published field trial, 6 of 20 cats experienced remission. Here is a figure from the publication by Prof Pedersen et al:
As you would expect, the antiviral was most effective against cats with the acute form of FIP, effusive FIP, but less so against non-effusive FIP. One advantage of GC376 over GS-441524 is that it can be dissolved in water, so the injections aren't as nasty.
I have heard that the patent for GC376 was bought by Anvive and that they will market it as an FIP treatment in future, but I do not have evidence for this to show you. However, it may be worth watching the Anvive website.
Interferons are the broad-spectrum antivirals that the body produces. They are fairly species specific, so it is more effective to use feline interferon than human interferon, although the latter is better than nothing. Until GS-441524 pills become commercially available, Feline Interferon Omega (Virbagen Omega) remains my go-to treatment for cats with FIP, although I am looking at another option at present.
interferon omega (Virbac, France)
Dr Ishida used corticosteroids in his study, but they reduce the life span of cats with FIP (Legendre et al, 2017), so for many years now I have been recommending meloxicam instead (provided blood pressure and kidney function are normal), and have been achieving remission and even some cures (Addie et al, 2022).
Dose for effusive FIP: IFN omega was initially given subcutaneously at 1 MU/kg every other day, and then twice every week for variable period if remission was seen.
Dose for non-effusive FIP: 100,000 Units per cat per day (dilution instructions are below). Once diluted (in water or saline) IFN Omega maintains its potency in the fridge for up to 3 weeks, so keep most IFN Omega in the freezer until needed.
It is very important to begin treatment as soon as possible after the onset of clinical signs.
Virbagen Omega comes in vials of 10 million units. It is reconstituted with 1ml of diluent. To get 100,000 Units/ml, divide one vial into 10 x 0.1ml aliquots in 10 one ml syringes and freeze 9 of them. Put 4.9mls of saline or water into a small clean tube and add one of the 0.1mls of Virbagen Omega to it: you now have 5 mls of diluted interferon: store it in the fridge (where it will keep up to 3 weeks). Show the cat's guardian how to withdraw 0.5mls of the diluted interferon (which now has 100,000 units of interferon per dose). Get the cat's guardian to do the syringe filling and the dosing in front of you: we vets are so used to handling syringes that we forget that most people have never handled a syringe in their lives. Some cats will take the interferon on food, but to be certain the cat gets the dose, tilt the head with the mouth closed and introduce into the commisure of the lips, wait until you see the cat swallow before releasing the head.
Remember that reconstituted, diluted Virbagen Omega
lasts only up to 3 weeks in the fridge.
Suppliers: Virbagen Omega can be obtained from your Virbac representative. From abroad, it can be bought from Abbeyvet, who can be contacted at email@example.com (you need to email them, because Virbagen isn't obvious from their website) .
In the USA, Virbagen Omega is stocked by The Animal Medical Centre, 510 East 62nd Street, New York, NY 10065. Telephone: (212)-329-8724
In effusive FIP 30 i.u./daily can be used, or larger doses of interferon can be given by intramuscular injection daily (104 - 106 i.u. per day). By 6-7 weeks, if the cat is still alive, interferon will no longer work at this dose because the cat will make antibodies against it.
To obtain human interferon-alpha (Roferon or Intron A), write a prescription for your local pharmacist. Obviously, in areas where feline interferon is available it is preferable as it is likely to have more effect than the human interferon.
Diluting human interferon
*In the UK: 2ml tubes are available from Sarstedt, supplier's ref: 72.694.006. Fax: 0116 236 66099 Tel: 0116 235 9023.
To get 104 i.u./ml put 1 x 1 million i.u. vial of Intron A or Roferon into 99ml sterile saline and divide into 1ml doses and freeze. For 105 i.u./ml use 9mls saline and proceed as above. For 106 i.u./ml use the whole vial.Yu et al, 2020) prior to Prof. Pedersen's discovery of GS-441524 and the nucleoside analogue has pretty much supplanted research on mefloquine, which is far less effective than GS-441524 in treating FIP. Nevertheless there remain patients whose people cannot afford the expensive GS pills, and so mefloquine is a possible alternative.
Dose: a quarter of a 250mg Lariam pill every 3 days.
Itraconazole is an anti-fungal but was recently reported to be able to reduce type I feline coronavirus in the laboratory. (Takano et al, 2019) Unlike GS-441524, there is a commercially available veterinary preparation for cats. This can be given to tide cats over until a specific anti-viral is available, but it does NOT cure FIP, even in combination with meloxicam and VIrbagen Omega feline interferon. Nor does it reliably stop cats from shedding virus in their faeces: sometimes it reduces the virus quantity, but it does not consistenly prevent FCoV shedding as far as we know at time of writing. In addition, cats lose weight while on this treatment.
Dose: 10mg/kg orally
Do NOT use Entyce along with Itraconazole.
Because FIP is an immune mediated disease, therapy sometimes includes suppressing the immune response, for example, with glucocorticoids, which can have lethal consequences if the diagnosis is erroneous (e.g. in toxoplasmosis, or bacterial peritonitis or pleurisy). Before embarking on any of the following therapies, it is essential to ensure that the diagnosis is correct. See Diagnosis of FIP. Cats receiving immunosuppressants should also receive antibiotic cover to protect them against other infections. It is also important to maintain the cat's general nutrition status, by adding real meat, vitamins and antioxidants.
Prednisolone - NOT RECOMMENDED
Prednisolone - NOT RECOMMENDED unless for palliative end of life care
Presnisolone is relatively safe and tends to make the cat feel better, it stimulates his or her appetite; prednisolone is inexpensive and available everywhere. However, prednisolone suppresses both the humoral and cell-mediated immune response and alternative anti-inflammatory treatments are more effective in the treatment of FIP: Hugo and Reading (2015) reported prolonged survival—787 days—in a 4 year old cat with effusive FIP, whom they treated with meloxicam and one month of metronidazole and Tramadol.
When prednisolone is used, it is absolutely essential that the doses BE REDUCED to a level which keeps the individual cat comfortable. I am frequently shocked to learn of veterinary surgeons who forget the half the dose of corticosteroids every 7-10 days: for example, this was not done in the Ritz study and 13 of the cats died of secondary bacterial infections.
Prednisolone has the advantage of also being the treatment for lymphocytic cholangitis, which can be mistaken for FIP, so where the diagnosis is in doubt between FIP and lymphocytic cholangitis, prednisolone can be given to assess the response: the cat with lymphocytic cholangitis has a good chance of recovery, the cat with FIP unfortunately will die. Prednisolone should never be used in cats with toxoplasmosis, or leishmaniasis, neither is it safe in cases of septic peritonitis or pleurisy, which is why cytology is a very important part of effusive FIP diagnosis, as there will be many more white blood cells in the effusion of a cat with sepsis, and a good cytologist will detect the bacteria or fungi.
Dose: 2 mg/kg/sid given by mouth for 7-10 days
Prednisone is not effective in cats (Trepanier, 2009)Hugo and Reading, 2015) Meloxicam, rather than glucocorticoids, was also used in 10 experimentally-infected cats who recovered using an antiviral called GS-441524. (Murphy et al, 2018)
Dose: 0.05 mg/kg BW, per os, q24h
Be sure to obtain the owner's consent for using a drug not licenced for cats.
Dose: 50-100mg at night. CANNOT BE USED IN PREGNANT CATS as it is teratogenic.
Polyprenyl immunostimulant (PI or PPI, called VetImmune) - do NOT use corticosteroids along with PPI
Although publications on PI were mainly on non-effusive cases, I recommend PI in any FIP case who is lymphopenic. In work I have not yet published, I saw a dramatic improvement in lymphocyte levels in 5 cats out of 6. In my recent paper, four cats in the recovered group and one in the remission group were treated with PI amongst other things. Even if the cat is being treated with GS-441524, GC376 or Mutian X, I would recommend also treating with PPI if the lymphocyte count is below normal.
Dose: 3.0 mg/kg orally of Polyprenyl Immunostimulant three times a week (can be used daily initially in severe cases).
I found the following video made by a cat's guardian, demonstrating how she doses her pet:
GS-441524 pills: 10mg of active ingredient per kg bodyweight until acute phase protein (alpha-1 acid glycoprotein (AGP) or serum amyloid A, SAA) levels consistently return to normal, or for up to 12 weeks. Most cats only require up to 7 or 8 weeks of treatment.
I recommend giving 10-14 days of a double dose (i.e. 20mg/kg) of antiviral at the outset of treatment to clear the brain of virus: this precaution seems to prevent neurological FIP relapses.
Once the cat has had two consecutive AGP or SAA tests within normal limits:then stop the pills and use oral Virbagen Omega at 100,000 units per cat per day per os.
In some countries, vets are able to use Remdesivir injections to treat FIP and that may be the only option, but it's not the best option (see above).
If GS-441524 pills are not available, my go-to protocol to treat effusive FIP is to drain the effusion, give Virbagen Omega to the site of the effusion, then s/c q48 hours after resolution of the effusion, and meloxicam as the anti-inflammatory of choice.
Feline interferon omega: 1 million units/kg/sc/q48 hours until recovery
Meloxicam (provided blood pressure and kidney function are normal): 0.05 mg/kg per os, sid.
If GS-441524 or EIDD (molnupiravir) pills are not available (see above) then my go-to protocol for non-effusive FIP therapy would be Virbagen Omega at 100,000 units per cat per day by mouth. and meloxicam (provided the cat's kidney function and blood pressure are normal). I have I have little personal experience of Polyprenyl Immunostimulant, the person with most experience using it is Dr Legendre whose paper is open access. However, in my experience it is effective at reversing lymphopenia.
Show the cat's guardian how to withdraw 0.5mls of the diluted interferon (which now has 100,000 units of interferon per dose). Get the cat's guardian to do the syringe filling and the dosing in front of you: we vets are so used to handling syringes that we forget that most people have never handled a syringe in their lives. Some cats will take the interferon on food, but to be certain the cat gets the dose, tilt the head with the mouth closed and introduce into the commisure of the lips, wait until you see the cat swallow before releasing the head.
Remember that reconstituted, diluted Virbagen Omega lasts only up to 3 weeks in the fridge.
Feline interferon omega: 100,000 units/kg/per os sid until recovery
Meloxicam (provided blood pressure and kidney function are normal): 0.05 mg/kg per os, sid.
GS-441524: 5mg/kg (e.g. Mutian X pills, twice this dose for Bova GS-441524) for up to 12 weeks. If neurological or intra-ocular signs are present: 10mg/kg is required. Note: it is best to ask the antiviral supplier about their recommended doses for the clinical presentation of an individual cat.
GS-441524 pills: 5-10mg/kg for 5 to 7 days (depending on the drug brand) unless the diarrhoea is caused by the colonic form of FIP, in which case the non-effusive protocol should be used.
Do NOT USE INJECTABLE FORMS OF GS-441524 because they do not adequately reach the gut, so they don't reliably stop FCoV shedding, furthermore, there is a risk of the low dose in the gut giving rise to drug-resistant FCoV mutants.
Ivermectin dose: 0.25mg/kg q24h in divided doses for 4 weeks, plus zinc picolinate (quarter of a Solgar 22mg pill per cat q24h for 2 weeks).
Vitamin B12 injections should be given to all cats with FCoV-associated diarrhoea once a week.
FCoV-associated diarrhoea is ameliorated (but not totally cured) by chicken and pumpkin cat food (e.g. Applaws or Almo Nature chicken and pumpkin tinned food) and Protexin Pro-kolin enterogenic probiotics. Fortiflora probiotics are also helpful if the Protexin brand is not available but don't use any other probiotic brand unless you have had a bacteriology laboratory grow them: we grew a number at our laboratory in the University of Glasgow Veterinary School and were appalled by what we found. Dr Weese had a similar experience with pet foods claiming to contain probiotics.
S-adenosyl-L-methionine (SAMe, e.g. Denamarin, Hepatosyl)
Used to protect the liver if using a nucleoside analog drug which can be hepatotoxic, or if FIP itself has caused raised liver enzymes.
Vitamin B12 (e.g. Cobalaplex pills by Protexin) should be given to all cats with FIP or FCoV-associated diarrhoea for several reasons:
Vitamin B complex
Multivitamins B are a good appetite stimulant and can be obtained from health food shops or chemists (I particularly like the one from Boots chemists in the UK). Dose: paediatric dose.
Vitamin B1 (thiamine)
Many sick cats are actually deficient in vitamin D (Titmarsh et al, 2015, 2017 & 2020), therefore it would be wise to supplement it in cats initially presenting with FIP. However, it must be used with caution because of its role in calcium homeostasis there are more cases of vitamin D intoxication in the veterinary literature than there are of deficiency. Therefore I would recommend only using vitamin D3 supplementation for only a brief period (days or weeks) and constantly checking levels of blood Ca.
Dose: 10mg/kg every 48-72 hrs per os.
Avoid amoxycillin/clavulanic acid because it can inhibit interferon-gamma, which is essential for FIP survival.
Choose from the following
(in the UK):
Remember to warn the owner
that the cat's urine could become more strong smelling with this
The AGP level is often the first to fall if treatment is having a positive effect because the acute phase proteins are a measure of inflammation, although in some cats the Hct rises to normal before AGP returns to normal (Addie et al, 2022). Other positive signs include resolution of clinical signs, lymphocyte count increasing, globulin levels decreasing, and the albumin: globulin ratio(A:G) increasing, Hct increasing and reticulocytes appearing in blood smears and weight increasing. Negative signs are AGP remaining high, globulins staying high or increasing, A:G decreasing, lymphocyte count decreasing, weight loss. An increase in bilirubin is a very poor prognostic sign (Tsai et al, 2011). When Hct gets to below 20% and stays there, i.e. is non-regenerative (no reticulocytes seen on blood smear examination) then the cat should probably be humanely euthanased if your clinical opinion is that he or she is no longer getting any happiness out of life. Clearly, if the cat is distressed at any point in the treatment, then euthanasia will be required.
Sadly, without treatment cats with effusive feline infectious peritonitis usually only survive a few days, possibly weeks at best. Cats with non-effusive FIP can last many weeks or months, though after neurological signs begin euthanasia usually ensues fairly rapidly.
For AGP testing see Veterinary Diagnostic Services at the University of Glasgow, Scotland, UK.
Staging for effusive FIP prognosis to help you to assess whether treatment has a chance of helping or not
In this staging system (based on the study of Tsai et al, 2011) shown in the video below the severity of effusive FIP can be worked out, which will give you an idea of whether or not it is worth obtaining special drugs to treat, or whether it is worthwhile continuing treating a case. Look at the parameter in the left hand column, then look at where the result of your case falls in the range, then put the score for that parameter into the next free column in the grey shaded cells. Finally work out the total score for your case. You can download the excel file here: http://www.catvirus.com/downloads.html: the total score will automatically fill in the cell at the bottom.
Interpreting the total score for your case:
While this isn’t an absolutely exact predictor, it does give a ballpark indicator of prognosis.
1. Make sure the FIP diagnosis is correct
To read the full pdf explaining the rules please download it here.
To watch videos on the explanations for the rules, please subscribe to my YouTube, Bitchute or Odysee channels (Rumble is not presently available in France due to censorship, so I am no longer able to upload there).
L-lysine should NEVER be given to a cat with FCoV infection or FIP because it is antagonistic to arginine which is essential for immune function.
Corticosteroids - see above.
Itraconazole - see above.
Thromboxane Synthetase Inhibitors
Two cats with abdominal effusions
were treated with ozagrel hydrochloride with success (Watari et al, 1998). However, follow up studies failed to confirm the usefulness of this compound.
""Feline Infectious Peritonitis and Coronavirus" - download an ebook written for cat guardians or purchase the physical version from Amazon.
I'd like to thank all the donors to the Angelica FIP trust, to the catvirus subscribers whose generous donations made my research possible. Enormous thanks go to the human families of cats who have had FIP, who have generously given of their time, and samples and data from their cats, to enable research without deliberate infection of laboratory cats. A BIG THANK YOU also to all the veterinary surgeons who have contributed to my studies.
Addie D.D., 2004 Feline Infectious Peritonitis. Veterinary Interferon Handbook. Ed: Karine de Mari. Virbac. 108-117
Addie D.D.2008 Feline infectious peritonitis – therapy and prevention. Kirk’s Current Veterinary Therapy XIV Edited by: John D. Bonagura, DVM, MS, DACVIM, David C. Twedt, DVM, DACVIM. Saunders, Elsevier.1295 – 1299
Addie, D.D.. Feline coronavirus. 2012 Infectious Diseases of the Dog and Cat. 4th edition. Editor: Greene, Craig. Published by W.B. Saunders Elsevier Company, 11830 Westline Industrial Drive, St. Louis, Missouri 63146, USA. ISBN 978-1-4160-6130-4 92-108
Addie DD. Curran S, Bellini F, Crowe B, Sheehan E, Ukrainchuk L, Decaro N. 2020a. Oral Mutian® X stopped faecal feline coronavirus shedding by naturally infected cats. Res. Vet. Sci. 130:222-229. doi: 10.1016/j.rvsc.2020.02.012.
Addie DD, Covell-Ritchie J, Jarrett O, Fosbery M. 2020b. Rapid Resolution of Non-Effusive Feline Infectious Peritonitis Uveitis with an Oral Adenosine Nucleoside Analogue and Feline Interferon Omega. Viruses 12, 1216; doi:10.3390/v12111216
Addie, D.D.; Silveira, C.; Aston, C.; Brauckmann, P.; Covell-Ritchie, J.; Felstead, C.; Fosbery, M.; Gibbins, C.; Macaulay, K.; McMurrough, J.; Pattison, E.; Robertson, E. Alpha-1 Acid Glycoprotein Reduction Differentiated Recovery from Remission in a Small Cohort of Cats Treated for Feline Infectious Peritonitis. Viruses 2022, 14, 744. https://doi.org/10.3390/v14040744
Addie DD, Bellini F, Covell-Ritchie J, Crowe B, Curran S, Fosbery M, Hills S, Johnson E, Johnson C, Lloyd S, Jarrett O. Stopping Feline Coronavirus Shedding Prevented Feline Infectious Peritonitis. Viruses. Viruses 2023, 15, 818. https://doi.org/10.3390/v15040818
Černá P, Ayoob A, Baylor C, Champagne E, Hazanow S, Heidel RE, Wirth K, Legendre AM, Gunn-Moore DA. Retrospective Survival Analysis of Cats with Feline Infectious Peritonitis Treated with Polyprenyl Immunostimulant That Survived over 365 Days. Pathogens. 2022;11(8):881. doi: 10.3390/pathogens11080881.
Dickinson PJ, Bannasch M, Thomasy SM, Murthy VD, Vernau KM, Liepnieks M, Montgomery E, Knickelbein KE, Murphy B, Pedersen NC. 2020. Antiviral treatment using the adenosine nucleoside analogue GS-441524 in cats with clinically diagnosed neurological feline infectious peritonitis. J Vet Intern Med. 34(4):1587-1593. doi: 10.1111/jvim.15780.
Hartmann K, Ritz S. 2008 Treatment of cats with feline infectious peritonitis. Vet Immunol Immunopathol. 123(1-2):172-5.
Hartmann K, Day MJ, Thiry E, Lloret A, Frymus T, Addie D, Boucraut-Baralon C, Egberink H, Gruffydd-Jones T, Horzinek MC, Hosie MJ, Lutz H, Marsilio F, Pennisi MG, Radford AD, Truyen U, Möstl K; European Advisory Board on Cat Diseases. Feline injection-site sarcoma: ABCD guidelines on prevention and management. J Feline Med Surg. 2015;17(7):606-13.
Katayama M, Uemura Y. Therapeutic Effects of Mutian® Xraphconn on 141 Client-Owned Cats with Feline Infectious Peritonitis Predicted by Total Bilirubin Levels. Vet Sci. 2021;8(12):328. doi: 10.3390/vetsci8120328.
Krentz, D.; Zenger, K.; Alberer, M.; Felten, S.; Bergmann, M.; Dorsch, R.; Matiasek, K.; Kolberg, L.; Hofmann-Lehmann, R.; Meli, M.L.; Spiri, AM., Horak J.,Weber, S., Holicki, CM., Groschup, MH., Zablotski, Y., Lescrinier, E., Koletzko, B., von Both, U., Hartmann, K. 2021. Curing Cats with Feline Infectious Peritonitis with an Oral Multi-Component Drug Containing GS-441524. Viruses. 13, 2228.
Legendre AM, Bartges JW. 2009 Effect of Polyprenyl Immunostimulant on the survival times of three cats with the dry form of feline infectious peritonitis. J Feline Med Surg. 11 624-626
Legendre AM, Kuritz T, Galyon G, Baylor VM, Heidel RE. 2017 Polyprenyl Immunostimulant Treatment of Cats with Presumptive Non-Effusive Feline Infectious Peritonitis In a Field Study. Front Vet Sci. 4:7.
Maunder CL, Day MJ, Hibbert A, Steiner JM, Suchodolski JS, Hall EJ. 2012
Murphy BG, Perron M, Murakami E, Bauer K, Park Y, Eckstrand C, Liepnieks M, Pedersen NC. The nucleoside analog GS-441524 strongly inhibits feline infectious peritonitis (FIP) virus in tissue culture and experimental cat infection studies. Vet Microbiol. 2018 Jun;219:226-233.
O'Brien, DP & Packer, RA (2010) Metabolic encephalopathy: organic acidurias. In August, JR (Ed): Consultations in feline internal medicine. Vol 6. Elsevier Saunders, Philadelphia. pp:595
Pedersen NC, Kim Y, Liu H, Galasiti Kankanamalage AC, Eckstrand C, Groutas WC, Bannasch M, Meadows JM, Chang KO. Efficacy of a 3C-like protease inhibitor in treating various forms of acquired feline infectious peritonitis. J Feline Med Surg. 2017 Sep 1:1098612X17729626.
Pedersen NC, Perron M, Bannasch M, Montgomery E, Murakami E, Liepnieks M, Liu H. 2019. Efficacy and safety of the nucleoside analog GS-441524 for treatment of cats with naturally occurring feline infectious peritonitis. J Feline Med Surg. 21(4):271-281
Roy, M.; Jacque, N.; Novicoff, W.; Li, E.; Negash, R.; Evans, S.J.M. Unlicensed Molnupiravir is an Effective Rescue Treatment Following Failure of Unlicensed GS-441524-like Therapy for Cats with Suspected Feline Infectious Peritonitis. Pathogens 2022, 11, 1209. https://doi.org/10.3390/pathogens11101209
Simpson KW, John Fyfe, Angelyn Cornetta, Amy Sachs, Dalit Strauss-Ayali, Stephen V. Lamb, Thomas J. Reimers 2001 Subnormal Concentrations of Serum Cobalamin (Vitamin B12) in Cats with Gastrointestinal Disease J Vet Intern Med 15:26–32
Swann JW, Szladovits B, Glanemann B: Demographic Characteristics, Survival and Prognostic Factors for Mortality in Cats with Primary Immune-Mediated Hemolytic Anemia. Journal of Veterinary Internal Medicine 2016, 30:147-156.
Szemiel AM, Merits A, Orton RJ, MacLean OA, Pinto RM, Wickenhagen A, Lieber G, Turnbull ML, Wang S, Furnon W, Suarez NM, Mair D, da Silva Filipe A, Willett BJ, Wilson SJ, Patel AH, Thomson EC, Palmarini M, Kohl A, Stewart ME. In vitro selection of Remdesivir resistance suggests evolutionary predictability of SARS-CoV-2. PLoS Pathog. 2021;17(9):e1009929. doi: 10.1371/journal.ppat.1009929.
Takano T, Hohdatsu T, Hashida Y, Kaneko Y, Tanabe M, Koyama H. 2007b A "possible" involvement of TNF-alpha in apoptosis induction in peripheral blood lymphocytes of cats with feline infectious peritonitis. Vet Microbiol. 119(2-4):121-31
Takano T, Azuma N, Satoh M, Toda A, Hashida Y, Satoh R, Hohdatsu T. 2009 Neutrophil survival factors (TNF-alpha, GM-CSF, and G-CSF) produced by macrophages in cats infected with feline infectious peritonitis virus contribute to the pathogenesis of granulomatous lesions. Arch Virol. 154(5):775-81.
Takano T, Akiyama M, Doki T, Hohdatsu T. Antiviral activity of itraconazole against type I feline coronavirus infection. Vet Res. 2019 Jan 18;50(1):5.
Tanaka Y, Sato Y, Osawa S, Inoue M, Tanaka S, Sasaki T. 2012. Suppression of feline coronavirus replication in vitro by cyclosporin A. Vet Res. 43(1):41.
Titmarsh H, Kilpatrick S, Sinclair J, Boag A, Bode EF, Lalor SM, Gaylor D, Berry J, Bommer NX, Gunn-Moore D, Reed N, Handel I, Mellanby RJ. 2015. Vitamin D status predicts 30 day mortality in hospitalised cats. PLoS One. 10(5):e0125997. doi: 10.1371/journal.pone.0125997.
Titmarsh HF, Cartwright JA, Kilpatrick S, Gaylor D, Milne EM, Berry JL, Bommer NX, Gunn-Moore D, Reed N, Handel I, Mellanby RJ. 2017. Relationship between vitamin D status and leukocytes in hospitalised cats. J Feline Med Surg. 19(4):364-369. doi: 10.1177/1098612X15625454.
Titmarsh HF, Woods GA, Cartwright JA, Kilpatrick S, Gaylor D, Berry J, Gow A, Bommer NX, Gunn-Moore D, Handel I, Mellanby RJ. 2020. Low vitamin D status is associated with anaemia in hospitalised cats. Vet Rec. 2020:vetrec-2019-105626. doi: 10.1136/vr.105626.
Trepanier L. 2009. Idiopathic inflammatory bowel disease in cats. Rational treatment selection. J Feline Med Surg. 11(1):32-8.
Yu J, Kimble B, Norris JM, Govendir M. 2020. Pharmacokinetic Profile of Oral Administration of Mefloquine to Clinically Normal Cats: A Preliminary In-Vivo Study of a Potential Treatment for Feline Infectious Peritonitis (FIP). Animals (Basel). 10(6):E1000. doi:10.3390/ani10061000
Watari T, Kaneshima T, Tsujimoto H, Ono K, Hasegawa A. 1998 Effect of thromboxane synthetase inhibitor on feline infectious peritonitis in cats. J Vet Med Sci. 60(5):657-9.
Weiss Richard C. 1994 Feline
Infectious Peritonitis Virus: Advances in Therapy and Control in
Consultations in Feline Internal Medicine
2. Edited by John R. August. Published by W.B. Saunders Company.
Harcourt Brace Jovanovich, Inc., The Curtis Center, Independence
Square West, Philadelphia, PA 19106. pages 3-12
Dr Diane D. Addie 27 Nov 2023
2000 - 2023 Dr.