A complete guide to treating Feline Infectious Peritonitis in cats.
Feline Infectious Peritonitis (FIP) was once considered untreatable. With antiviral treatment using GS-441524, cats now recover. This guide explains what Feline Infectious Peritonitis (FIP) is, how to recognize it at each stage, how the treatment works, and how to care for your cat through the full course.
Four parts, from the first signs to full recovery.
Everything you need to understand Feline Infectious Peritonitis and the treatment protocol, set out in the order you will need it.
- 1
The three stages
How Feline Infectious Peritonitis progresses, and why timing changes the outcome.
- 2
Recognize the Symptoms
The wet, dry, neurological and ocular forms, and what each one looks like.
- 3
The treatment
GS-441524, the 84 day protocol, and how the dose is set.
- 4
Home care and diet
Feeding, hydration, monitoring, and what to avoid during treatment.
What is Feline Infectious Peritonitis?
Feline Infectious Peritonitis (FIP) is caused by a mutation of feline coronavirus (FCoV). FCoV itself is common and usually harmless, spreading through saliva, faeces and shared environments, and often causing nothing worse than mild diarrhea. In a small number of cats it mutates into Feline Infectious Peritonitis, which is fatal if left untreated. There are two forms, and both can progress to neurological or ocular disease if treatment starts late.
- 1
Wet Feline Infectious Peritonitis
The more common form. Fluid builds up in the abdomen or chest, causing a swollen belly, weight loss and difficulty breathing. It tends to move quickly.
- 2
Dry Feline Infectious Peritonitis
Progresses without fluid build up. Instead, small nodal masses called granulomas form on the organs. It usually moves more slowly, with less obvious signs.
Neurological and ocular Feline Infectious Peritonitis can develop from either form if treatment starts late, affecting the brain, nerves or eyes. These cases are dosed differently, so tell your specialist exactly what your vet found.
The three stages of Feline Infectious Peritonitis
The earlier treatment starts, the higher the chance of a full recovery. Recognizing the stage helps you act quickly.
- 1Stage one
Early
Intermittent fever, slight loss of appetite, weight loss and lethargy. Easy to miss, and the best time to start.
Start now - 2Stage two
Mid
Early signs worsen, plus a bloated belly known as ascites, anemia, diarrhea or jaundice.
Act urgently - 3Stage three
Late
Mid signs worsen, plus stopped eating, cloudy eyes, loss of coordination or paralysis.
Treat immediately
Recognizing symptoms of Feline Infectious Peritonitis
Signs vary with the form and the stage. Wet Feline Infectious Peritonitis is the most common and shows fluid build up early. Watch for these.
- 1Persistent fever
- 2Lethargy
- 3Loss of appetite
- 4Drastic weight loss
- 5Swollen belly, wet form
- 6Difficulty breathing
- 7Vomiting
- 8Diarrhea
- 9Jaundice
- 10Anemia
- 11Cloudy eyes, ocular form
- 12Loss of coordination
Treating Feline Infectious Peritonitis in cats
GS-441524 is the antiviral that changed the outlook for Feline Infectious Peritonitis. Developed in research led by Dr. Niels Pedersen at UC Davis, it has been shown in clinical trials to be highly effective, and our specialists have run the protocol since 2019.
The GS-441524 protocol.
Given by subcutaneous injection or oral capsule, GS-441524 is a full 84 day course. Most cats show visible improvement within the first 5 days, but the course must be completed in full, even after your cat looks well, or the infection can return.
- Daily dosing for 84 days, by injection or oral capsule.
- A blood test roughly every 30 days to monitor progress.
- Dose is set by weight and never reduced mid course. If your cat gains weight, the dose goes up to match.
- 1
Injectable or oral
GS-441524 injections suit all types of Feline Infectious Peritonitis, including severe cases. Oral capsules suit cats sensitive to injections. Our specialists recommend which fits your cat.
- 2
Relapse guarantee
If your cat relapses within 12 months of completing an 84 day course on CureFIP products, we cover up to 50% of the relapse treatment cost. Conditions apply, including a final blood test.
Home care and diet
Good care through the 84 days makes a real difference to how your cat recovers. Focus on these four areas, and keep your specialist updated.
- 1
Nutrition
Feed a well balanced diet, higher in protein and lower in carbohydrate. Freshly cooked fish or chicken tempts a poor appetite. If your cat has diarrhea, a few days of dry food can help settle it.
- 2
Hydration
Cats with Feline Infectious Peritonitis dehydrate easily. Keep fresh, clean water available at all times and watch that your cat is drinking.
- 3
A calm environment
Cats under treatment stress easily. Keep things quiet and comfortable, keep the litter tray clean, and give plenty of gentle attention.
- 4
Monitoring
Track appetite, energy and weight, and report changes to your specialist. The 30 day blood tests confirm the treatment is working.
Avoid during treatment: fluoroquinolone antibiotics, immune boosters such as vetriDMG or transfer factor, supplements containing lysine, and spot on flea treatments. Also avoid vaccination and non emergency surgery until the course is complete.
Common questions about Feline Infectious Peritonitis
Can Feline Infectious Peritonitis be treated?+
Yes. Feline Infectious Peritonitis (FIP) was once fatal, but antiviral treatment with GS-441524 has a 92% success rate. The earlier treatment starts, the better the outcome.
How long is the treatment?+
84 days, run without gaps even after your cat looks well again. Stopping early is the most common reason treatment fails.
How quickly will I see improvement?+
Most cats improve within the first 5 days. Appetite usually returns first, then energy. This is not the finish line, because the full 84 day course still has to be completed.
Should I choose injections or oral capsules?+
Injections suit all types of Feline Infectious Peritonitis, including severe cases. Oral capsules suit cats sensitive to injections. Our specialists recommend which fits your cat, free of charge.
Is Feline Infectious Peritonitis contagious to other cats?+
No. A cat with Feline Infectious Peritonitis does not pass it to other cats, dogs or people. The underlying feline coronavirus can spread between cats, but it rarely mutates into Feline Infectious Peritonitis.
Can GS-441524 be used with other medications?+
GS-441524 can be given alongside other medicines to support your cat's overall health. Lysine, however, is not recommended during treatment. Always check with your specialist first.
What is the relapse guarantee?+
If your cat relapses within 12 months of completing an 84 day course on CureFIP products, we cover up to 50% of the relapse treatment cost. A final blood test and some other conditions apply.
More questions are answered in the CureFIP FAQ.
Think your cat may have Feline Infectious Peritonitis?
Feline Infectious Peritonitis moves fast, so act early, when treatment works best. Browse the available treatments to get started.
This page is for general educational purposes and does not replace veterinary advice. Always consult a qualified veterinarian for diagnosis and a treatment plan tailored to your cat.