Cat respiratory infection: symptoms and treatment

Upper respiratory infections (URI) — commonly called "cat flu" — are extremely common, especially in young cats, rescue cats, and multi-cat households. The good news: most healthy adult cats recover fully with supportive care.

What causes cat flu?

- Feline Herpesvirus (FHV-1) — accounts for ~50% of cases. Once infected, cats carry the virus for life and may have periodic flare-ups triggered by stress, illness, or immunosuppression.
- Feline Calicivirus (FCV) — accounts for ~40% of cases. Some strains cause painful mouth ulcers (calicivirus stomatitis). A virulent systemic strain (VS-FCV) is rare but can be fatal.
- Chlamydophila felis — causes eye-dominant URI with conjunctivitis and minimal respiratory signs.
- Bordetella bronchiseptica — less common; causes coughing rather than sneezing.

Symptoms to watch for

- Sneezing (often repetitive), nasal discharge (clear → yellow/green as secondary bacteria set in)
- Eye discharge, squinting, or conjunctivitis
- Loss of appetite — a major concern because cats can develop fatty liver disease (hepatic lipidosis) if they stop eating for more than 24–48 hours
- Fever, lethargy, drooling, mouth ulcers (calicivirus)
- Laboured breathing or open-mouth breathing (emergency)

Treatment

- Keep nostrils clear — wipe away discharge with a warm damp cloth. Steam from a hot shower can help clear congestion.
- Warm food to encourage eating — cats rely heavily on smell, and congestion kills their appetite.
- Ensure hydration — offer water, wet food, or low-sodium chicken broth.
- Vet treatment: antibiotics (for secondary bacterial infection), antiviral therapy (famciclovir for herpes), and appetite stimulants if needed.

Vaccination

The core cat vaccine (F3 or F4) covers Herpesvirus and Calicivirus. It does not prevent infection but significantly reduces severity. Keep vaccinations current.