FIP Resources for Veterinarians

Feline Infectious Peritonitis (FIP) is a disease that continues to perplex and challenge veterinary professionals worldwide. With no legal access to treatment for veterinarians in the U.S., FIP was often seen as a death sentence for cats. However, recent advancements in antiviral therapy have shown that effective treatment for Feline Infectious Peritonitis (FIP) is now a reality. 

The following information was written by Dr. Stephanie Sorrell, Prof. Séverine Tasker, Dr. Sam Taylor, Dr. Emi Barker, and Prof. Danielle Gunn-Moore

What is feline infectious peritonitis (FIP)?

FIP is a severe disease in cats caused by feline coronavirus. COVID-19 is also caused by a coronavirus but the coronavirus causing FIP is not the same and only infects cats. Feline coronavirus is commonly found in the feces of cats and research has shown that infection is very common among cats. Thankfully, in most, it causes mild diarrhea or no signs at all. However, in a small number of cats, the virus changes (mutates) inside the cat, and interacts with the cat’s immune system in a certain way, resulting in FIP. Finding coronavirus in a cat doesn’t mean they have FIP, and it is not possible to consistently tell the difference between a coronavirus causing FIP, and one causing no signs of illness. Further tests must be performed by a veterinarian to diagnose FIP.

What cats are more likely to get FIP?

We do not know why certain cats develop FIP and others do not, but it is diagnosed more often in:

  • Cats under 2 years of age
  • Pedigree cats
  • Cats in multi-cat homes

Symptoms of Feline Infectious Peritonitis (FIP)

What are the symptoms of FIP in cats?

Cats with FIP can show a variety of signs as the disease can affect any organ in the body. The most common signs are:

  • Lethargy/tiredness
  • Eating less and losing weight
  • A high temperature

Additionally, the disease can cause fluid to accumulate in the abdomen/belly, chest and occasionally around the heart (so called ‘wet’ FIP) so owners may notice a swollen, rounded belly or the cat may have difficulty breathing. The non-effusive (‘dry’) form can affect any organ including the intestines, lymph nodes, brain, kidneys and eyes. Many cats have a combination of ‘wet’ and ‘dry’ forms of FIP and some cats have pale, slightly yellow gums.

If the brain or spinal cord (neurological FIP) is affected cats will show signs such as fits, an abnormal way of walking (wobbly gait), changes in behavior or trembling for example.

If the eyes are affected (ocular FIP) they may look cloudy, bloody or with different pupil sizes, and the cat may show signs of pain such as holding the eye or eyes closed.

Different Types of Feline Infectious Peritonitis (FIP)

Wet Effusive Feline Infectious Peritonitis FIP


When fluid develops in a body cavity - especially the abdomen and/or chest

Dry FIP Cat Photo 2


When no fluid forms

Neurological FIP

Neurological FIP

Affecting the brain and/or spinal cord

Ocular Feline Infectious Peritonitis FIP

Ocular FIP

Affecting the eyes

Treatment for Feline Infectious Peritonitis (FIP)

How is Feline Infectious Peritonitis (FIP) in cats treated?

In the past, there was no effective treatment for FIP but thankfully times have changed and there are antiviral medications available with good results in treating FIP. These drugs are legally available in many countries and have been shown to be safe and effective (through clinical studies), although they can be expensive.

Current recommendations are to treat for 12 weeks to allow full clearance of the disease. This can seem a long time but gives cats the best chance of recovery. It may be that shorter courses can be recommended in the future but for now 12 weeks of treatment is required. Different types of FIP require different amounts (dosages) of antiviral medication, FIP cats showing neurological and/or ocular signs being treated with higher dosages. However, there is variation in how cats respond, and adjustments may be needed during the treatment period. If a cat is not responding as expected, the amount of antiviral medication may need to be increased.

Drugs include:

  • GS-441524: tablets that can be used from day 1 of treatment and is usually the preferred treatment. Now available at Stokes Pharmacy!


  • Remdesivir: an injectable medication given under the cat’s skin or into a vein.

Treatment for FIP Is Now Available in the U.S. from Stokes Pharmacy

Stokes Pharmacy has formed an exclusive partnership with the Bova group to offer a U.S.-made oral treatment for FIP. This treatment is supported by Bova’s unique drug formula, which has been utilized in clinical research studies across the globe and is currently in use in the UK and Australia.

Stokes Pharmacy GS-441524 Benefits

  • The only oral formula identical to the Bova formula used in clinical studies
  • Our compounded quad scored tablets are smaller than a U.S. dime
  • Available by a veterinarian prescription and office use in permitted states
  • Oral tablets help cat owners avoid the pain and stress from daily injections
  • In the UK, the majority of cats with FIP are now treated with oral GS-441524 alone
  • Online via our ordering platform, iFill 
  • Available nationwide with 1-2 business days in transit (overnight available upon request)
GS441524 Compounded FIP Treatment at Stokes Pharmacy

Ordering Made Easy.

3 Ways to Order:

E-form coming

Commonly Asked Questions

Can I, a licensed veterinarian, legally prescribe this medication?
FDA’s Center for Veterinary Medicine (CVM) has notified veterinarians that compounded GS-441524 falls under Guidance For Industry #256 and is allowed to be compounded and legally prescribed. Read the CVM’s statement here. 

Can my hospital purchase GS-441524 Tablets for office use? GS-441524 was nominated and is now on the GFI under review list for the animal drug bulk substances list in regards to GFI #256 office use. This means that GS-441524 50 mg tablets can be sold to hospitals for office use in all states except Arkansas, Maine, Massachusetts, New Mexico, New York, Oregon, Rhode Island and West Virginia. Veterinarians who work in a state that does not allow compounded medications for office use can prescribe the drug in a patient’s name.

How long does it take to ship and how long is it in transit?
Veterinary office orders are ready to ship same day with 1-2 business days in transit. Patient prescriptions will ship once we confirm payment and shipping information from the pet owner. Then it will be 1-2 business days in transit. Overnight shipping is also available upon request.

Is oral GS-441524 as effective as the injection?
Outcomes from treatment with GS-441524 as a sole oral treatment are comparable (complete response in 90%+) with combined treatment of remdesivir and GS-441524 or remdesivir alone (Taylor et al, 2023)

Where can I find more information?
More information about our GS-441524 formulation can be found via our FAQ sheet and our drug information sheet. There are also numerous studies and upcoming webinars featured on this page.

Upcoming FIP Webinar Series for Vet Professionals

FIP Treatment, from a death sentence to long-term survival:
The story so far.

Presented by Dr. Samantha Taylor, Dr. Sally Coggins, and Dr. Samantha Evans
May 30, 2024 | 5pm-6pm ET
RACE-Approved CE Credit Hours: 1 | Free to attend
Webinars are for veterinary professionals only. All webinars will be recorded and available to watch via our website on-demand, however CE credits will only be issued for those who tune in live. Limited Seats! Reserve your spot today!
This discussion will be presented by key FIP researchers from Australia, the UK and the US, this webinar will update clinicians regarding the recent, significant advancements in FIP treatment and how legal access to GS-441524 in the US unfolded.

Learning Objectives:
• This webinar will introduce the key antivirals of interest in FIP treatment.
• Participants will gain a concise and chronological review of the recent evidence-based literature in FIP treatment from around the globe
• Participants will gain an understanding of why compounded access to GS-441524 is legal in Australia, the UK/Japan and now the US and how the quality assurance of compounded formulations differs from unlicensed formulations

Details & Register

FIP Diagnosis: Now we can treat it, how sure do we need to be?

Presented by Dr. Samantha Taylor, BVetMed(Hons), CertSAM, DipECVIM-CA, MANZCVS, FRCVS
June 20, 2024 | 5pm-6pm ET
RACE-Approved CE Credit Hours: 1 | Free to attend
Webinars are for veterinary professionals only. All webinars will be recorded and available to watch via our website on-demand, however CE credits will only be issued for those who tune in live. Limited Seats! Reserve your spot today!
In this discussion, Sam aims to provide practical tips and strategies for diagnosing FIP, a challenging task. We will delve into the importance of lab results, the necessity of definitive tests like PCRs, and the appropriate timing for treatment trials.

Learning Objectives:
1. List common clinical presentations of FIP, and the differential diagnoses for these presenting signs.
2. Explain the key physical examination findings consistent with FIP.
3. Understand the most common clinical pathology and imaging findings that help you make a diagnosis of FIP.
4. Explain when definitive testing for coronavirus is needed and when to consider a treatment trial and how to monitor its effect.

Details & Register

Legal FIP Treatment in the USA: Learn how to start treating FIP cases in your practice.

Presented by Dr. Sally Coggins, BVSc (Hons I) MANZCVS (Feline Medicine), PhD Candidate (Science) Sydney School of Veterinary Science
June 27, 2024 | 8pm-9pm ET
RACE-Approved CE Credit Hours: 1 | Free to attend
Webinars are for veterinary professionals only. All webinars will be recorded and available to watch via our website on-demand, however CE credits will only be issued for those who tune in live. Limited Seats! Reserve your spot today!
This webinar aims to bring a very practical focus to ensure general practitioners feel confident to start readily treating these cases. FIP is no longer a death sentence. In fact, these are now some of the most rewarding cases you will treat.

Learning Objectives:
1. Participants will receive updates on current antiviral medications being utilized for treatment of feline infectious peritonitis.
2. Participants will gain information on how to optimize monitoring, with expected times to normalization for key clinicopathologic parameters and when to consider dose adjustments.
3. Key take-home messages around “what to avoid” when managing FIP cases will also be discussed.
4. This session will conclude with discussion of other antivirals to consider for combined or alternative treatment with refractory cases.

Details & Register

FIP Handouts and Downloads

FIP FAQ: Commonly Asked Questions and Answers for Veterinarians

This is the heading

Commonly asked questions and answers about FIP regarding diagnosis, treatment, and more!
Get My Copy

GS-441524 Drug Information Sheet

This is the heading

About the formulation available through prescription from Stokes Pharmacy
Get My Copy

FIP Diagnostic Tool

This is the heading

Source: The European Advisory Board on Cat Diseases (ABCD)

Published in September 2023

Get My Copy

FIP Update 2024: The Numbers Are In, What's New & Dr. Sally's Updated Treatment Protocols

This is the heading

Written by Dr. Sally Coggins

Published in Vet Vault Clinical, February 2024

Get My Copy

Clinical Study: Unlicensed antiviral products used for the at-home treatment of feline infectious peritonitis contain GS-441524 at significantly different amounts than advertised

This is the heading

Written by Alycia M. Kent, MPH; Su Guan, PhD; Nicole Jacque; Wendy Novicoff, PhD; and Samantha J. M. Evans, DVM, PhD, DACVP

Published in JAVMA April 2024

Get My Copy

Clinical Study: Thirty-two cats with effusive or non-effusive feline infectious peritonitis treated with a combination of remdesivir and GS-441524

This is the heading

Written by Jodie Green, Harriet Syme, and Sarah Taylor

Published in the Journal of Veterinary Internal Medicine, June 2023

Get My Copy

Clinical Study: Retrospective study and outcome of 307 cats with FIP treated with legally sourced veterinary compounded preparations of remdesivir and GS-441524

This is the heading

Written by Sam Taylor et al

Published in the Journal of Feline Medicine and Surgery, July 2023

Get My Copy

Clinical Study: Outcomes of treatment of cats with feline infectious peritonitis using parenterally administered remdesivir, with or without transition to orally administered GS-441524

This is the heading

Written by Sally Coggins, et al

Published in the Journal of Veterinary Internal Medicine, June 2023

Get My Copy

Clinical Study: Feline Infectious Peritonitis: European Advisory Board on Cat Diseases Guidelines

This is the heading

Written by Tasker, S.; Addie, D.D.; Egberink, H.; Hofmann-Lehmann, R.; Hosie, M.J.; Truyen, U.; Belák, S.; Boucraut-Baralon, C.; Frymus, T.; Lloret, A.; et al

Feline Infectious Peritonitis: European Advisory Board on Cat Diseases Guidelines.

Get My Copy

Our Family of Brands

503A Traditional Compounding Pharmacy

503B FDA Registered Outsourcing Facility

Stokes/Epicur Online Ordering Platform

Never miss an update from our brands.

Become a subscriber to get all the latest updates from Stokes and Epicur about FIP news, webinars, medications, and more!

Our website uses cookies to enhance your browsing experience. By clicking “Accept” you are agreeing to our use of cookies. Learn more in our Privacy Policy.

If you select “Decline” we will respect your privacy, though your browsing experience may be limited.