Kitten on vet table being checked

Cat flu

Cat flu is a virus that, much like human flu, can leave them with a fever and runny nose and eyes.

Cat flu is not usually serious in healthy cats. But it can be serious, and even fatal, in kittens and adult cats with underlying illnesses, so it's important to get your pet to the vet.

As with human colds, there are several viruses that can cause it. 

Symptoms of cat flu

It can take as long as two weeks for signs of flu to appear. When it does, it can cause: 

  • runny eyes and nose
  • sore throat
  • mouth ulcers
  • dribbling
  • sneezing
  • loss of voice
  • cat fever

If your cat is showing signs of flu, contact your vet for advice. This is especially important if you have a kitten that is showing symptoms. 

Cat flu treatment

Your vet may prescribe antibiotics if symptoms are severe, but they are not always needed. You will also be given guidance on how to care for your pet at home. 

Diagnosis to identify which type of cat flu they have may be made by taking swabs and looking for the virus but, in most pet cats, this is not necessary as there's no specific treatment.

If a cat is very poorly and unable to eat, hospitalisation may be necessary. 


Preventative treatment is best and a vaccine is available from your vet.

Two doses of vaccine are needed initially, followed by regular boosters.

It's particularly important to remember that your cat will need to be fully up to date with vaccinations if they will be going to a boarding cattery when you are on holiday.

Is a vaccine always effective?

No vaccine gives complete protection but it's still worth vaccinating your cat, as it's the best preventative measure. It may also help to reduce symptoms even if they are infected.

It’s also important to know that even vaccinated cats can become carriers and infect other cats, without showing any symptoms. 

The vaccine cannot prevent symptoms from occurring if the animal already has cat flu.


Anti-inflammatories are sometimes prescribed to relieve symptoms. 

Some antivirals are also available, though most aren't licensed in cats. They can also be very expensive and aren’t always effective. 

Lubricants and eye drops

Depending on which virus has caused the cat flu and your cat's general level of health, there is a risk of long-term damage to the eyes. Eye ulcers are often found and, particularly in kittens, can progress to cause serious damage, and even lead to the loss of an eye. 

Treatments such as lubricants may be prescribed to treat sore eyes. We have some great advice on how to give your cat eye drops.

If your cat or kitten has sore looking eyes or they are partially closed, seek immediate veterinary attention.

Cat flu in kittens

Kittens get some immunity from their mothers which fades as they get older. They'll then become at risk to cat flu. Mum cats with cat flu can also infect their kittens without showing illness themselves. The kittens either get flu or become symptom-free carriers. 

Looking after a cat with cat flu

In most cases your vet will ask you to care for your pet at home.

Reduce stress

Stress can make your cat's illness worse. So, it's important to keep their life as stress-free as possible. Look out for the signs of stress in your cat and learn how to reduce this.

Wipe nose and eyes

Wiping your cat's nose and eyes will:

  • help your cat feel better
  • enable them to smell their food
  • help them to breathe easier

Wipe away discharge from the nose and eyes regularly using a cotton wool pad soaked in warm water.

Keep them fed and hydrated

Cats can easily become dehydrated when they have cat flu because they lose their sense of smell and taste. This leads to them eating and drinking less.

To keep them hydrated and fed it’s best to mix in foods to their usual meals that are easy to eat and have strong smells. We suggest warm foods like:

  • sardines
  • pilchards
  • roast chicken
  • tuna

As well as keeping them hydrated, encouraging your cat to drink also helps to loosen catarrh (mucus that builds up in the back of the nose and throat).

Cats that cannot eat may need to be hospitalised for treatment.

Help them breathe

Steam may help to loosen mucus in their airways. So, letting your cat in the bathroom when you have a bath or shower can help them to breathe more easily.

Be sure to look out for any signs of stress and remove your cat from the room if they look worried.

What can happen if cat flu goes untreated?

Like human flu, once the virus has damaged the delicate lining of the nose and airways, bacterial infections can enter and cause complications, such as pneumonia. So it's important that you contact a vet if you suspect your cat has flu.

What causes cat flu?

Cat flu is usually caused by:

  • calcivirus
  • herpes
  • bordetella bronchiseptica
  • chlamydophila felis


The calicivirus exists in lots of slightly different forms called 'strains'. Vaccination against calicivirus is difficult because the vaccine cannot cover all the strains, so it's not fully protective.

Calicivirus can cause mouth ulcers as well as lameness in young kittens.

Many cats will recover and are no longer contagious after one or two years. 

Herpes virus

The herpes virus is often more severe and is more likely to produce eye ulcers. The virus has only one strain, so vaccination against it works better. 

Following infection with the herpes virus, it's thought that all cats become carriers. They produce the virus in their tears, saliva and nose fluid, but only every now and then. This means swabs taken from these cats will not always detect the virus. 

Cats that are carriers remain so for life.

Bacteria: bordetella bronchiseptica

There are also several types of bacteria that may cause flu. One of these – bordetella bronchiseptica – is what causes kennel cough in dogs. It's thought that it may be possible for cats to catch 'flu' from dogs. This bacterium often seems to affect the lungs as well. 

It can usually be successfully treated with antibiotics. Although a vaccine is available, it's only given sometimes, such as in breeding catteries.

Bacteria: chlamydophila felis

This mainly produces sore, red, runny eyes, sometimes with a mild 'cold'. 

Some types of antibiotics are effective, and a vaccination is available, although it is not fully protective. It can be difficult to get rid of this form of cat flu completely from a group of cats.

Are there long-term effects of cat flu?

Once infected, cats shed virus particles in their saliva and the discharge from their nose and eyes. 

Particles can survive for a week or longer in their environment, so a cat does not even need to meet another to catch the illness. It can easily be spread by contact with infected feed bowls or toys, or on people's clothing after touching an infected cat.

Carriers of cat flu

Following infection, many cats are left as carriers, which means they do not have any symptoms but can potentially infect others. 

Some carrier cats occasionally have a runny eye or nose for a few days. Recurrences of flu can follow stressful events, such as a visit to the vet or the arrival of a new cat in the house. 

Others are unlucky and are left with a permanent, lifelong, thick, runny nose, or 'chronic rhinitis' (inflammation of the nose lining). This happens because the delicate nasal lining has been damaged, allowing repeated bacterial infections for which antibiotics may provide only temporary relief.

Other side effects

It's thought that flu viruses, especially calicivirus, may contribute to long-term inflammation and soreness of the mouth, or gingivitis. This is a complicated condition, which is often difficult to cure and calicivirus may not be the only cause. 

Long-term drug treatment is often needed for control and in some cases extraction of the teeth may be needed.

— Page last updated 22/03/2024