Feline Calicivirus in Cats: A Vet’s 2025 Guide 😷🐱
By Dr Duncan Houston, BVSc
🧬 What is Feline Calicivirus (FCV)?
FCV is a highly contagious RNA virus in the Caliciviridae family, responsible for a significant portion of feline upper respiratory infections, often called “cat flu” :contentReference[oaicite:3]{index=3}.
🐾 Who’s at Risk?
- Kittens, seniors, immunocompromised cats
- Cats in shelters or multi-cat households :contentReference[oaicite:4]{index=4}
- What makes FCV tricky: many strains—up to 50% of URIs involve FCV :contentReference[oaicite:5]{index=5}
⚠️ Symptoms & Unusual Signs
Classic signs include:
- Sneezing, nasal & ocular discharge
- Fever, lethargy, poor appetite
- Painful mouth ulcers/stomatitis :contentReference[oaicite:6]{index=6}
Less common:
- Limping/polyarthritis—also called “limping calicivirus” :contentReference[oaicite:7]{index=7}
- Inflammation beyond the respiratory tract (rare strains) :contentReference[oaicite:8]{index=8}
- Highly virulent systemic FCV (VS-FCV): facial swelling, edema, jaundice—up to 67% mortality :contentReference[oaicite:9]{index=9}
🧫 How is FCV Transmitted?
• Spread via saliva, eye/nose secretions—can travel meters via sneezes.
• Virus survives days to weeks in environment, especially damp areas :contentReference[oaicite:10]{index=10}.
• Carriers shed virus long-term—some after recovery :contentReference[oaicite:11]{index=11}.
🩺 Diagnosing FCV
- Physical exam with signs like ulcers and discharge
- PCR testing of swabs, virus culture confirms diagnosis :contentReference[oaicite:12]{index=12}
- Bloodwork and imaging if complications appear
💊 Treatment & Supportive Care
No cure—treatment focuses on comfort and preventing secondary infection:
- Steamy bathroom for 10–15 min twice daily :contentReference[oaicite:13]{index=13}
- Clean discharges with warm cloths
- NSAIDs for pain and inflammation :contentReference[oaicite:14]{index=14}
- Antibiotics against secondary infections :contentReference[oaicite:15]{index=15}
- Soft, warm, strong‑smelling food to stimulate appetite :contentReference[oaicite:16]{index=16}
- Fluids, hospitalization, nebulization for severe cases :contentReference[oaicite:17]{index=17}
- Joint pain treatment: corticosteroids, rest if limping occurs :contentReference[oaicite:18]{index=18}
🏥 Recovery & Long-Term Concerns
- Most recover in 1–3 weeks; mild cases resolve quicker :contentReference[oaicite:19]{index=19}
- Chronic carriers may shed intermittently :contentReference[oaicite:20]{index=20}
- Some develop chronic stomatitis or polyarthritis :contentReference[oaicite:21]{index=21}
- VS-FCV prognosis is grave—requires intensive care and isolation :contentReference[oaicite:22]{index=22}
🛡️ Prevention & Vaccination
- FVRCP vaccine includes FCV—initial series then boosters every 1–3 years :contentReference[oaicite:23]{index=23}
- Vaccine reduces disease severity, not full immunity :contentReference[oaicite:24]{index=24}
- High‑virulence strains (VS-FCV): specialized CaliciVax available :contentReference[oaicite:25]{index=25}
- Hygiene: isolate infected cats, clean fomites with bleach solution, ventilated spaces :contentReference[oaicite:26]{index=26}
📌 Practical Advice for Cat Parents
- 📅 Keep vaccines up to date
- 🧼 Clean and isolate when one cat is sick
- 💨 Use steam therapy during flare-ups
- 🍲 Offer palatable, warm soft food
- 💧 Ensure hydration—wet food/fountains
- 📱 Use Ask A Vet for ongoing advice; Woopf & Purrz products help reduce stress during illness
📝 Summary Table
| Area | Key Details |
|---|---|
| Virus | FCV, RNA Caliciviridae, ~50% URIs |
| Signs | Sneezing, discharge, ulcers, fever; sometimes limping or edema |
| Diagnosis | Clinical signs, PCR/swabs, imaging if needed |
| Treatment | Supportive: steam, meds, antibiotics, hydration |
| Prevention | Vaccination, hygiene, isolation |
| Outlook | Most recover; carriers possible; severe strains have high mortality |
🐾 For expert care and peace of mind, trust Ask A Vet—download our app anytime. Calm your cat with gentle solutions from Woopf and Purrz during recovery.
📢 Always consult your veterinarian for diagnosis or treatment.
© 2025 AskAVet.com
This article is general veterinary education and does not diagnose or treat an individual animal. Always confirm medication names, doses and interactions with the veterinarian who knows your pet.
If your animal is struggling to breathe, collapsed, bleeding heavily, seizing, or has eaten something toxic, contact your vet or the nearest emergency clinic now.
Animal Poisons Helpline (AU) 1300 869 738 · Animal Poisons Helpline (NZ) 0800 869 738 · ASPCA Animal Poison Control (US) (888) 426-4435
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Ask A Vet articles are written by Dr Duncan Houston BVSc, a practising veterinarian, unless another author is named in the byline.




