Cat flu

Content by Dr Siân Burwood MRCVS

Cat flu is not actually ‘the flu’ at all, but a common and well-recognised upper respiratory disease caused by viruses that produce flu-like symptoms. Many cats catch cat flu when they’re very young, and then have signs of the disease on-and-off throughout their life.

It can be very serious if caught in kittens or elderly cats whose immune systems don’t work very well. For this reason, it’s recommended that all cats are vaccinated against it every year, including house cats.

For cats who survive cat flu infection, they never fully clear the disease, and the viruses go latent in the body. This means that they start multiplying again when the body and immune system are under stress. As such, many cats with flu need to be seen by their vets frequently for chronic weepy eyes and runny nose, for eye ulcers and for early onset dental disease.

• Cat flu is a viral disease of the upper respiratory tract in cats
• It’s not caused by a flu virus, but mainly feline herpes virus and feline calicivirus
• It’s highly contagious between cats and – once caught – cannot be cured
• Infections vary from mild cold symptoms to severe life-threatening disease
• Vaccination is an effective and vital way to prevent cat flu, and boosters are needed every year

Cat flu is mostly caused by two viruses: feline herpes virus (FHV) and feline calicivirus (FCV). These viruses are spread by contact with infected body fluids such as saliva, aerosol from coughs and sneezes, and through cat bites… although they can also live on items in the cat’s environment for up to 10 days and cause infection that way.

• Feline herpes virus is more commonly associated with eye ulcers, conjunctivitis and inflammation of the throat that causes appetite loss and coughing.
• Feline calicivirus is more commonly associated with inflammation in the mouth, causing painful ulcers in the short term and gingivitis in the longer term.

More than 90% of cat flu cases are due to infection with one or both of these viruses. But there may also be secondary infection with bacteria such as Bordetella bronchiseptica and Chlamydia felis.

There are no particular breeds more likely to get cat flu, but there are definitely particular groups of animals more at risk.

Kittens and young cats who haven’t been vaccinated are especially at risk of cat flu as their immune system is not fully developed. They’re more likely to experience severe disease and go on to develop lifelong problems if they survive.

Other cats with immune system problems – such as the elderly and those with other health conditions – are also more at risk. For this reason, yearly vaccination is considered essential for all cats.

Cats who live in large groups are also at high risk of cat flu, as the viruses can spread more easily and build up in large numbers in the environment. This includes colonies of feral cats and in rescue centres, but equally applies to pedigree breeding catteries and homes with lots of cats.

It’s essential to maintain rigorous hygiene standards and keep up with annual vaccination to prevent this. If you’re buying a pedigree cat, make sure you see proof of vaccination for all animals.

The signs and symptoms of cat flu include:

• Sneezing
• Coughing
• Discharge from the eyes and nose, either clear or green
• Loss of appetite
• Lethargy
• High temperature
• Dehydration
• Eye ulcers
• Mouth ulcers

Not all cats will show all symptoms, and every cat will show them to different degrees. For some, they’re just a bit snotty and under the weather. For others, it can be a life-threatening condition.

Diagnosis of cat flu is usually made presumptively based on clinical history, vaccination history and clinical signs. This is enough to allow your vet to start treating the symptoms and supporting your cat through.

If you and your vet wish to get a more exact diagnosis, or if there’s a worry that more unusual bacteria or viruses are involved, a swab can be taken from the throat or eyes that is then sent to an external laboratory.

Treatment of cat flu mainly focuses on supportive care to help the cat’s own body and immune system fight back. Much like when we have the flu, this involves:

• Keeping the temperature under control
• Providing warmth and comfort
• Cleaning away discharges from the eyes and nose
• Tasty, easy-to-eat food and lots of fluids

Antibiotics may be needed if there’s a risk of secondary infection, and pain relief may be needed if there’s a sore throat.

If cases are mild they can be treated at home, but more severe cases may need to be admitted to hospital for more aggressive nursing care – involving fluid therapy, supportive feeding and nebulisation.

Severe cases or those that keep coming back (for example with recurrent eye ulcers) may benefit from specific anti-viral therapy.

The prognosis for cat flu can be really variable. And while life-threatening cases are fortunately rare, the lifelong nature of the disease and the secondary issues it causes means that it’s always something to be taken seriously.

Some cats may become very poorly when they catch flu, requiring long hospital stays until they’re able to go home. Others may clear the initial infection easily, but be plagued by recurrent eye ulcers and dental issues for the rest of their life.

“Prevention is definitely better than cure when it comes to cat flu. I would strongly recommend that all cats, indoors or otherwise, keep up with their annual vaccinations as a very effective way to do that.

“We still see cat flu commonly in practice, usually in cats who are rescued after they’ve already caught it – but also in pedigree cats where the breeders have not been as strict in their hygiene and vaccination protocols as they should be.

“Cat flu can cause a lifetime of hassle and heartache for both cats and caregivers, so it really is important to do what we can to prevent spread. Even for cats who already have the flu, vaccination can help reduce the severity of symptoms and keep it under control”

Dr Siân Burwood MA VetMB MRCVS

If you’re thinking about buying a Petgevity Lifetime Plus policy, we’ll consider all pre-existing conditions – including cat flu – when offering cover for your cat*.

When you apply for cat insurance, you need to let us know: 

• Which medical conditions they’ve had in the last two years 
• Their health status now

Find out more about Petgevity’s cat insurance for pre-existing conditions.