Feline Infectious Peritonitis (FIP)

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Key Points

Feline infectious peritonitis (FIP) is a serious viral infection caused by a mutated form of feline coronavirus (FCoV)
There are two forms:
- Wet / effusive – characterised by fluid accumulation in body cavities
- Dry / non-effusive – characterised by granuloma formation in organs
The clinical signs depend on the form affecting the cat but lethargy, anorexia and pyrexia are typical in most infected cats
Diagnosis is based on the clinical presentation, effusion analysis (if present) and rarely histopathology or cytology
Antivirals (e.g. GS-441524, remdesivir and molnupiravir) have revolutionised treatment in the last few years
- FIP was once considered a fatal disease
- Cost of treatment is often prohibitive for many clients
Prevention focuses on reducing exposure to FCoV but this is challenging as it is so widespread in cat populations

Differential Diagnoses

Septic peritonitis
Lymphoma
Toxoplasmosis

Educational content only. This factsheet is for general veterinary education and is not a substitute for professional veterinary advice, diagnosis, or treatment. Not for use in an emergency — contact a veterinarian or emergency service. Full disclaimer →