Feline Infectious Peritonitis (FIP)
A severe, immune-mediated viral disease in cats caused by a mutation of common feline coronavirus (FCoV).
💬 In Plain English
Feline Infectious Peritonitis (FIP) happens when a benign and common stomach bug that many cats carry (feline coronavirus) mutates inside an individual cat’s body into a dangerous immune-attacking virus. It typically strikes young cats under 2 years old and comes in two forms: "wet" (effusive) FIP, which causes thick, straw-colored fluid to build up in the chest or belly causing a pot-bellied appearance or difficulty breathing; and "dry" (non-effusive) FIP, which creates inflammatory nodules in the eyes, brain, liver, or kidneys. Once considered 100% fatal, breakthrough antiviral treatments (like GS-441524) have transformed FIP into a curable disease in veterinary medicine.
🔬 Clinical & Technical Depth
For Vets & TechniciansFormal Clinical Definition
Fatal immune-mediated polyserositis and granulomatous vasculitis resulting from systemic replication of mutated feline enteric coronavirus (FCoV) within monocytes and macrophages.
Why Veterinarians Use It
Veterinarians diagnose FIP using fluid analysis (Rivalta test), PCR, and clinical signs to distinguish it from lymphoma or bacterial peritonitis.
Clinical Context Encountered
Discussed when a young cat or kitten develops a persistent fever unresponsive to antibiotics, abdominal distension, or neurological tremors.
Clinical Reference Guide (Medical Condition)
Typical Presentation
Lethargy, fluctuating fever, weight loss, distended pot belly or labored breathing.
Management Priorities
- Antiviral therapy (GS-441524)
- Cententesis for respiratory relief
- Nutritional support
- •Open-mouth breathing or extreme lethargy in a kitten with abdominal distension requires immediate emergency oxygen and fluid drainage.
❓ Questions to Ask Your Veterinarian
Take these actionable questions with you to your next clinic visit or appointment:
- 1Is this the wet (effusive) or dry (non-effusive) form of FIP?
- 2Can we test the fluid from the belly or chest with a Rivalta test and coronavirus PCR?
- 3How can we legally access GS-441524 antiviral therapy (compounded or approved oral/injectable)?
Academic & Clinical References
- 2022 AAFP/EveryCat Feline Infectious Peritonitis Diagnosis GuidelinesOrganization: American Association of Feline Practitioners (AAFP) • Accessed: 2026-01-10https://catvets.com