About Cat Flu

What is Cat Flu?

Cat flu is a common illness, like a human cold, that affects the upper respiratory tract of cats. It can be caused by a number of infectious agents, including viruses and bacteria.  It can cause a runny nose and eyes, and a sore throat. Other symptoms include aches and pains in the muscles and joints, mouth ulcers, dribbling, sneezing, loss of voice and fever. Cat flu is not usually serious in adult cats, however, all cats with symptoms of cat flu should see the vet.

With cat flu, eye ulcers are often found and, particularly in kittens, can progress to cause serious damage to the eye. If your cat or kitten has a sore looking or partially closed eye, seek immediate veterinary attention.

Unfortunately, cat flu still persists, despite the availability of vaccines. The cats most severely affected include the very young, the very old and those with a damaged immune system or other serious underlying illnesses.  In some cases, it can be serious, even fatal.  However, in the majority of cases, cat flu can be recovered from and lived with, and flare ups can be treated, just like us humans when we have a cold and flu.

What causes cat flu?

Around 80% of cases of cat flu are caused by one of 2 viruses, Feline Herpesvirus (FHV) or Feline Calicivirus (FCV). The viruses may both be present and once they have damaged the lining of an infected cat’s respiratory tract, the disease may be further complicated by additional bacterial infections.

Other causes of cat flu include bacteria such as Chlamydophila Felis – previously known as Chlamydia – and Bordetella Bronchiseptica – the cause of kennel cough in dogs.

Once infected, cats shed virus particles in nasal and eye discharges and in saliva. Although ill cats are the biggest source of infection, some healthy cats are carriers of the viruses. 'Carriers' do not suffer from symptoms of the disease but they too can shed virus particles and infect other cats. Particles can survive for up to a week in the environment, so a cat does not even need to meet another to catch the illness. It can easily be spread to other cats by contact with infected feed bowls or toys, or on people's clothing after touching an infected cat. 

1. FHV (Feline Herpesvirus)

Transmission The virus is spread by discharge from the nose/eyes and from saliva of an infected cat. The virus can also survive in the environment and be passed on to other cats. It is a very common cause of cat flu.  

Symptoms Seen most commonly in kittens, symptoms include fever, sneezing, discharge from the eyes and nose, conjunctivitis and occasionally ulcers on the surface of the eye. Ulcers may also develop on the tongue. Anorexia can be a problem, especially in kittens, leading to dehydration. 

If a pregnant cat becomes infected, this may result in pregnancy loss.  Adult cats are less severely affected.    An infected cat may not show any outward sign of illness, but can act as a ‘carrier’ cat, passing the infection on to others. 

Treatment  Once a cat has had feline herpes virus, it is infected for life and may suffer from flare ups (in the same way people with human herpes virus get recurrent cold sores), but the first infection is usually the most severe.  Flare ups may occur after stress or illness, or if the cat is immuno-suppressed.  To treat the initial infection or subsequent future flare ups, keep the eyes and nose clear of discharge by gently bathing the eyes and nose (e.g. with cotton wool pads and water). Antibiotics may be given to prevent secondary bacterial infections, and eye drops may be given if conjunctivitis is present.

 2. FCV (Feline Calicivirus)

Transmission  The virus can by spread by direct contact with affected cats, or by air-borne spread, or contamination of the environment. Cats that recover can occasionally become carriers, and able to transmit the infection to other cats.  

Symptoms  Its symptoms include fever, loss of appetite, discharge from the nose/eyes and sneezing. It can also cause drooling and severe mouth ulcers.  More severe strains can lead to pneumonia.  Stress or illness can cause flare-ups of the virus. 

Treatment is supportive, bathing the cat's face, encouraging feeding with soft food, and antibiotics to prevent secondary infection.  Severely affected cats with mouth ulceration may need to go on a drip and be given pain killers.  

Vaccination prevents infection with some strains of feline calicivirus but not all. However, cats that do become infected generally have much milder symptoms than those that are unvaccinated.

3. Chlamydophila

Can produce a mild form of cat flu. Discharge and redness of the eyes is a common feature of this infection.

4. Bordetella

Causes flu-like signs like those described above but may also progress to the chest, causing a serious infection and a relatively high death rate in kittens. Cats infected with Bordetella may develop a cough.

How is cat flu treated?

Antibiotics may help because, just as with 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.

Nursing care at home is important. A blocked nose and mouth ulcers may stop a cat eating and drinking, leading to dehydration, which can be particularly dangerous in kittens. Because your cat may have lost its sense of smell and have a sore throat, sloppy, strong-smelling foods should be offered. Suggestions include sardines, pilchards, roast chicken, or a special diet available from vets. Mixing water with any normal food is a good idea too. Cats that cannot eat may need to be hospitalised for treatment.

Encourage your cat to drink, as fluids help to loosen thick catarrhal secretions. Wipe away discharges from the nose and eyes regularly using salt water (a teaspoonful of salt to a pint of water). Steam inhalations help to loosen catarrh, so let the cat in the bathroom when you have a bath or shower.

Can cat flu be prevented?

There are lots of different strains of virus, and, just as with human flu, the vaccine is not effective against them all. Two doses of vaccine are needed initially, followed by regular boosters. You should consult your vet for details. It is 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.

Even vaccinated cats can become carriers without showing any symptoms and can infect other cats. Kittens initially get some immunity from their mothers but, as they get older, this fades and they become susceptible to the infection. Infected mothers can infect their kittens without showing illness themselves. The kittens either get flu or become symptom-free carriers. It can take as long as two weeks for signs of flu to appear, so one reason for apparent vaccine “failures”, especially in kittens, may be that they are already infected at the time of vaccination. The vaccine, as with all vaccines, cannot prevent symptoms from occurring if the animal already has the infection at the time of vaccination.

Can I catch cat flu from my cat?

No! Humans cannot catch cat flu.

I'm thinking about adopting a cat or kitten that has had cat flu - should I?

Many cats have suffered from or are carriers of cat flu.  If a cat or kitten is ready for homing, it means it is well. As long as you are prepared to give your cat the supportive treatment required if you notice symptoms of cat flu, they can live normal, happy, long and healthy lives.

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