Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: The most common viral infections in cats are feline herpesvirus and calicivirus (the main causes of “cat colds”), panleukopenia (a severe, often fatal gut infection in unvaccinated cats), FeLV and FIV (retroviruses that weaken the immune system), and feline coronavirus, which can cause FIP. Core vaccines protect against herpesvirus, calicivirus, and panleukopenia, and FeLV vaccination is recommended for kittens. FIP, once almost always fatal, can now often be treated with antiviral drugs.
Common viral infections
- Feline herpesvirus-1: sneezing, eye and nose discharge, eye ulcers. Cats often carry it for life, with flare-ups during stress
- Feline calicivirus: sneezing, mouth ulcers, fever, and sometimes lameness
- Panleukopenia: vomiting, diarrhea, fever, and severe illness in kittens. See a vet immediately
- FeLV: anemia, lymphoma, and immune suppression. See FeLV
- FIV: spread mainly by deep bite wounds. Many infected cats live normal lives
- Feline coronavirus and FIP: most coronavirus infections are mild, but a mutated form causes FIP, with fever, fluid in the belly or chest, and weight loss
- Rabies: rare but fatal, and legally required vaccination in many areas
How they spread
- Direct contact, sneezing, and shared bowls and litter boxes
- Contaminated hands, clothing, and surfaces (panleukopenia survives for months)
- Bites (FIV)
See a vet promptly for
- Not eating for more than a day
- Vomiting and diarrhea in a kitten
- Fever, lethargy, or breathing difficulty
- Eye squinting or cloudiness
- A swollen belly or unexplained weight loss
Treatment
- Supportive care: fluids, nutrition, anti-nausea medication
- Antiviral drugs for some herpesvirus eye infections
- Antiviral treatment for FIP (such as GS-441524 or remdesivir), which has transformed outcomes. Ask your vet about availability
- Antibiotics only for secondary bacterial infections
Prevention
- Core vaccines for all cats, and FeLV vaccination for kittens and at-risk adults
- Test new cats for FeLV and FIV
- Keep cats indoors
- Quarantine new cats
- Reduce stress to limit herpes flare-ups
Sources
- Stone AE, et al. 2020 AAHA/AAFP Feline Vaccination Guidelines. J Feline Med Surg. 2020
- Little SE, et al. 2020 AAFP Feline Retrovirus Testing and Management Guidelines. J Feline Med Surg. 2020
- Cornell Feline Health Center: Feline infectious peritonitis
- Merck Veterinary Manual: Feline panleukopenia
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.