By Dial A Vet Veterinary Team
Cat flu is not influenza. It is the everyday name for upper respiratory tract infection in cats, and it is very common in shelters, catteries and multi-cat homes. Most adult cats recover within one to three weeks with good nursing. Kittens, older cats and cats with other illnesses can become seriously ill, mainly because a blocked nose takes away their sense of smell and they stop eating. Knowing which signs can be nursed at home and which need a vet makes a real difference.
Key takeaways
- Feline herpesvirus type 1 (FHV-1) and feline calicivirus (FCV) cause most cat flu. Chlamydia felis and Bordetella bronchiseptica are less common causes.
- Typical signs are sneezing, runny nose and eyes, conjunctivitis, mouth ulcers, fever and poor appetite.
- A cat that has not eaten for more than 24 hours, especially a kitten, needs a vet.
- Many recovered cats carry herpesvirus for life and can have flare-ups during stress.
- Core vaccinations do not always prevent infection, but they greatly reduce how sick cats get.
What causes cat flu
- Feline herpesvirus (FHV-1): causes sneezing, nasal discharge and conjunctivitis, and can cause corneal ulcers. After infection, the virus hides in nerve tissue, and stress can reactivate it.
- Feline calicivirus (FCV): often causes mouth and tongue ulcers, drooling and sometimes lameness in kittens. Rare virulent strains cause severe disease. See feline calicivirus.
- Chlamydia felis: mainly causes conjunctivitis, often starting in one eye.
- Bordetella bronchiseptica: can cause coughing and more serious chest infection, particularly in crowded settings.
Bacteria often take advantage of the damaged lining of the nose and eyes, causing thick yellow or green discharge.
How it spreads
Cats shed the viruses in saliva, eye and nose discharge. Spread happens through direct contact, sneezed droplets, and shared bowls, litter trays, bedding and human hands. Calicivirus can survive in the environment for weeks. Carrier cats can look healthy and still shed virus, especially during stress, after moving house or after giving birth.
Signs to watch for
- Sneezing and a runny or crusty nose
- Watery or sticky eyes, red conjunctiva, squinting
- Ulcers on the tongue, gums or nose, and drooling
- Fever and lethargy
- Reduced appetite or refusing food
- Breathing through the mouth because the nose is blocked
- Coughing in some cases
- Hoarse or lost voice
When it is an emergency
Go to a vet the same day if your cat:
- Is breathing with an open mouth or seems to be struggling to breathe
- Has not eaten for 24 hours, or a kitten that has missed meals
- Is very lethargic, weak, or hiding and unresponsive
- Has a squinting or cloudy eye
- Is not drinking or seems dehydrated
- Has swelling of the face or paws, or is limping badly
Not eating is especially risky for overweight cats, which can develop fatty liver disease. Breathing problems in a cat are always urgent.
How vets diagnose cat flu
Diagnosis is often based on the signs and history, such as a recent stay in a cattery or a new kitten in the home. Your vet may take swabs from the eyes, nose or mouth for PCR testing to identify the cause. This is particularly useful in multi-cat homes, breeding catteries and shelters, or for severe or recurring cases. Fluorescein stain shows corneal ulcers. Chest X-rays may be needed if pneumonia is suspected.
Treatment overview
There is no single cure. Treatment focuses on supporting the cat while its immune system clears the infection:
- Fluids for dehydration
- Pain relief for mouth ulcers, which helps cats eat again
- Antibiotics if a bacterial infection is suspected
- Antiviral medication in some cats with severe herpesvirus eye disease
- Feeding support, sometimes with a temporary feeding tube in very sick cats
- Eye medication for conjunctivitis or ulcers
Your vet will decide what is appropriate for your cat.
Nursing your cat at home
- Gently wipe the eyes and nose with soft pads moistened with warm water or saline.
- Warm strongly smelling wet food slightly to help a blocked nose smell it.
- Offer food little and often, and hand feed if your cat accepts it.
- Sit your cat in the bathroom while you run a hot shower to let the steam loosen mucus. Never put a cat near hot water or a vaporiser with additives.
- Keep your cat warm, quiet and separate from other cats.
- Never give human cold and flu tablets or paracetamol. These are deadly to cats.
- Avoid essential oils and vapour rubs, which are toxic to cats.
Prevention
- Keep your cat up to date with core vaccinations. In Australia the F3 vaccine covers FHV-1, FCV and feline panleukopenia.
- Make sure catteries require current vaccination.
- Isolate new cats for a week or two and have them checked by a vet.
- Wash hands between cats, and keep bowls and litter trays separate when a cat is unwell.
- Reduce stress for known carrier cats.
FAQ
Can people or dogs catch cat flu?
The main cat flu viruses do not infect people or dogs. Bordetella can occasionally affect dogs and, rarely, people with weakened immunity.
How long is a cat contagious?
Cats can shed virus for weeks, and carriers may shed it intermittently for life.
Why did my vaccinated cat get cat flu?
Vaccines reduce severity rather than guarantee protection, and calicivirus has many strains.
Will my cat always have flare-ups?
Some herpesvirus carriers have occasional mild flare-ups during stress. Many never show signs again.
Talk with a vet
If your cat is sneezing, has sore eyes or has gone off food and you are not sure whether it needs a clinic visit, a Dial A Vet veterinarian can help you decide. Talk with Dial A Vet. Open-mouth breathing or a cat that has stopped eating needs an in-person vet today. For eye symptoms, see why cats' eyes water.
References
- Thiry E et al. Feline herpesvirus infection: ABCD guidelines on prevention and management. Journal of Feline Medicine and Surgery, 2009
- Radford AD et al. Feline calicivirus infection: ABCD guidelines on prevention and management. Journal of Feline Medicine and Surgery, 2009
- WSAVA Vaccination Guidelines for dogs and cats (Squires RA et al.), Journal of Small Animal Practice, 2024
- Cornell Feline Health Center: Feline upper respiratory infections
Disclaimer: Educational only. This page does not replace an examination or advice from your own veterinarian. If you are worried about your pet right now, contact your local vet or nearest emergency animal hospital.
