Feline Infectious Peritonitis (FIP)
This page is educational reference material for preparing questions. A licensed veterinarian examines the animal, makes the diagnosis, and sets the treatment.
Understanding FIP in cats including wet and dry forms, diagnosis, the GS-441524 treatment breakthrough, and prognosis for affected cats.
Causes and Risk Factors
Multiple factors can contribute to the development of this condition.
- Genetic predisposition: Certain breeds are at higher risk due to inherited traits
- Age: Some conditions are more common in kittens or senior pets
- Environmental factors: Diet, toxin exposure, stress, and living conditions play a role
- Underlying health issues: Other conditions may increase susceptibility
- Immune system status: Compromised immune function can predispose to disease (Merck Veterinary Manual)
Symptoms to Watch For
Early detection significantly improves treatment outcomes. Watch for these signs.
- Changes in appetite, water consumption, or weight
- Behavioral changes including lethargy, restlessness, or hiding
- Physical symptoms specific to the affected body system
- Changes in bathroom habits (frequency, appearance, straining)
- Visible discomfort, pain response to touch, or changes in posture
- Respiratory changes, coughing, or labored breathing
When to See the Vet Immediately
Run any significant dietary change past your vet before making it — they already know your cat's history, and existing conditions can make ordinary-seeming food swaps risky.
Diagnosis
FIP has no single blood test that proves it in the clinic. The case is built from the exam plus laboratory clues: high globulin, a low albumin-to-globulin ratio, and sometimes a lymphopenia. Wet FIP adds an effusion that is high in protein and relatively low in cells. A Rivalta test on that fluid supports the suspicion. PCR on the effusion can support the diagnosis, and a negative PCR does not clear a cat who still fits the picture.
Treatment Options
Supportive care treats fever, dehydration, and the effusion. The antiviral discussion, including compounded GS-441524 and the FDA's 2024 statement that compounded GS-441524 is unapproved, is in the questions on this page and is not repeated here as a dose. The prescribing veterinarian chooses the product and the plan. Surgery does not treat FIP.
Prevention and Management
- Regular veterinary checkups (as recommended by the AVMA for all companion animals) for early detection (annually, or semi-annually for seniors)
- Maintain a healthy weight through proper nutrition and exercise
- Keep vaccinations and preventive medications current
- Breed-specific health screenings recommended by your veterinarian
- Provide a low-stress, enriched environment
- Follow your vet's recommendations for diet and lifestyle modifications
Cost of Treatment
Treatment costs vary based on severity and duration.
| Treatment Type | Estimated Cost Range |
|---|---|
| Initial Diagnosis | $200 – $800 |
| Medication (monthly) | $30 – $200 |
| Ongoing Management (annual) | $500 – $3,000 |
Common Questions About Feline Infectious Peritonitis (FIP)
Is this condition curable?
Untreated feline infectious peritonitis is usually fatal. That is no longer the whole story. Nucleoside analogs such as GS-441524, prescribed by a veterinarian, have produced long remissions in published cohorts, including a 2023 Journal of Feline Medicine and Surgery series. The U.S. FDA said on May 10, 2024 that it does not intend to enforce approval requirements when GS-441524 is compounded for a specific cat under Guidance for Industry 256. The drug is still not FDA-approved, and some cats relapse, especially with neurologic disease.
How can I afford treatment?
The FIP invoice is a multi-week course of compounded GS-441524, plus the exams and bloodwork that adjust it. Ask the prescribing veterinarian which compounding pharmacy they use and what one week costs before you commit to the full course. Neurologic or ocular cases often need a longer or higher plan and a bigger total. Patient-specific prescriptions are how U.S. pharmacies dispense it. Do not buy unlabeled vials from social media.
Editorial and clinical review
This article was written by the Pet Care Helper AI editorial team and reviewed by Paul Paradis, editorial lead. We describe our verification workflow on the medical review process page and the clinical reference set on the editorial team page.
References checked for this page:
- ISFM Feline Medicine Guidelines — feline-specific guidance
- Cornell Feline Health Center — client-facing feline reference
- Journal of Feline Medicine and Surgery (JFMS) — peer-reviewed feline literature
- Merck Veterinary Manual — clinical reference
Disagree with something on this page? corrections@petcarehelperai.com — see the corrections log for how we handle published fixes.
Feline infectious peritonitis follows a mutation of a feline coronavirus inside that individual cat. Most cats that meet the common enteric coronavirus never develop FIP. The wet form puts fluid in the belly or the chest. The dry form brings fever and eye or neurologic signs. Diagnosis combines the history, imaging, and laboratory tests. Antiviral treatment is a veterinarian-managed plan. A persistent fever with a swollen belly should be seen promptly.