Cat Health
Cat Respiratory Infections UK — URI Symptoms, Causes & Treatment
Published Last updated 2 min read
Quick answer
Upper respiratory infections (URI) — often called cat flu — cause sneezing, nasal discharge, eye watering and fever. Most UK cats recover with supportive care, but kittens, seniors and cats with chronic disease can become seriously ill. Open-mouth breathing is an emergency.
Common signs of respiratory infection
- Sneezing — frequent or violent
- Runny nose — clear, yellow or green discharge
- Eye discharge — watery or thick
- Conjunctivitis — red, swollen eyes
- Reduced appetite (cats rely on smell to eat)
- Fever and lethargy
- Mouth ulcers (calicivirus)
Symptoms often worsen in the first week then gradually improve over two to three weeks. Some cats become chronic carriers, with signs recurring during stress.
Main causes in UK cats
| Agent | Notes |
|---|---|
| Feline herpesvirus (FHV-1) | Most common; lifelong carrier possible |
| Feline calicivirus (FCV) | Can cause mouth ulcers and lameness |
| Bordetella | More common in multi-cat households and shelters |
| Chlamydia felis | Primarily causes conjunctivitis |
Bacterial infections often develop secondary to viral illness, especially if nasal discharge becomes thick and green.
Home care while recovering
- Warm, humid environment — steam from a shower room can loosen nasal secretions
- Tempting food — warmed wet food with strong aroma; hand-feed if needed
- Clean eyes and nose — gently wipe discharge with warm water
- Isolation — separate food bowls and litter trays from other cats
- Hydration — ensure fresh water is always available; syringe water only if your vet advises
Never give human cold medicines or paracetamol to cats.
Veterinary treatment
Your vet may prescribe:
- Antibiotics for secondary bacterial infection
- Eye drops for conjunctivitis
- Antiviral medication in severe herpes cases
- Appetite stimulants or fluid therapy if dehydrated
- Nebulisation or oxygen for severe cases
Kittens under six months are most vulnerable. Hospitalisation may be needed if they stop eating entirely.
Prevention
- Vaccination — core UK cat vaccines include FHV-1 and FCV components
- Reduce stress — stress triggers flare-ups in carrier cats
- Limit exposure — avoid introducing new cats without gradual introduction
- Good hygiene — clean bowls and litter trays regularly in multi-cat homes
When to call the vet urgently
- Open-mouth breathing or gasping
- Blue or pale gums
- Kitten not eating for 24 hours
- Thick green nasal discharge with fever
- Eye becoming swollen shut
- Signs worsening after initial improvement
Sources & further reading
Facts in this guide are rewritten in plain English from publicly available UK advice. We name the organisation where a specific point comes from their guidance. Links below go to the original pages — use them to read the source material directly.
PETHEALTH+ is independent. These organisations do not sponsor, approve, or partner with this website. Guidance checked against sources listed below (last updated 2026-06-25).
Related guides
Frequently Asked Questions
- What causes respiratory infections in cats?
- Feline herpesvirus (FHV-1) and feline calicivirus (FCV) are the most common causes. Bordetella, Chlamydia and mycoplasma can also contribute. Stress and overcrowding increase risk.
- Is cat flu the same as a respiratory infection?
- Yes — 'cat flu' describes upper respiratory infections in cats, usually caused by viral agents. It is not influenza. Signs include sneezing, nasal discharge and eye problems.
- Can cat respiratory infections spread to other cats?
- Yes. Viruses spread through sneezing, shared bowls and direct contact. Isolate sick cats and wash hands between handling. Vaccination reduces severity but does not prevent all infections.
- When is a respiratory infection an emergency?
- Open-mouth breathing, blue gums, extreme lethargy, or a kitten refusing all food and water need urgent care. Nasal congestion can prevent eating — young and elderly cats dehydrate quickly.