What are the signs of cat flu (upper respiratory infection)?

Sneezing; Runny eyes and nose; Mouth ulcers; Fever; Loss of appetite (cats that cannot smell often stop eating).

When should I contact a veterinarian?

A cat that has not eaten for 24 hours, or a kitten with cat flu, should see a vet the same day.

Infectious disease · Updated 2026-09-29

Sneezing, runny eyes and nose caused mainly by feline herpesvirus and calicivirus; especially serious in kittens.

Prompt veterinary attentionCats

Highly contagious viruses and some bacteria spread by direct contact, sneezes and shared bowls.

Usually based on signs; swabs can identify the organism in shelters or severe cases.

Supportive care: fluids, appetite support, cleaning discharge, pain relief and antibiotics for secondary infection.

Core vaccination reduces severity. Herpesvirus stays in the body and can flare with stress.

Most adult cats recover in one to three weeks; kittens can become seriously ill.

What are the signs of cat flu (upper respiratory infection)?: Sneezing; Runny eyes and nose; Mouth ulcers; Fever; Loss of appetite (cats that cannot smell often stop eating).
What causes cat flu (upper respiratory infection)?: Highly contagious viruses and some bacteria spread by direct contact, sneezes and shared bowls.
How is cat flu (upper respiratory infection) diagnosed?: Usually based on signs; swabs can identify the organism in shelters or severe cases.
How is cat flu (upper respiratory infection) treated?: Supportive care: fluids, appetite support, cleaning discharge, pain relief and antibiotics for secondary infection.
Can cat flu (upper respiratory infection) be prevented?: Core vaccination reduces severity. Herpesvirus stays in the body and can flare with stress.
When should I contact a veterinarian?: A cat that has not eaten for 24 hours, or a kitten with cat flu, should see a vet the same day.