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What is Cat Flu?

Feline Flu...

What Is It?

Cat Flu is also known as Feline Respiratory Disease, and much like the human cold it displays many of the same symptoms. It is caused by the Feline Calicivirus (FCV) or by the Feline Herpes Virus (FHV).

It is very common in cats and kittens and can be spread via nasal or ocular secretions, saliva and direct contact between felines. Droplets from a cat sneezing can cover many metres – transmitting the infection vast distances.

Cat flu can be life threatening if it is left untreated, especially in very young kittens, elderly cats or cats with underlying illnesses such as kidney disease or thyroid problems.

Causes & Symptoms

Cat flu can affect cats of all ages but is commonly more severe in kittens.

Symptoms can vary depending on the strain of virus but can be a combination of any of the following:

  • Sneezing
  • Discharge from eyes and nose
  • Loss of appetite
  • Sore eyes / swollen conjunctiva
  • Lethargy / Low demeanour
  • Dribbling
  • Weight loss
  • Inappetence
  • Ulcers in the mouth
  • Ulcers in the eyes – which can cause irreversible damage and blindness
  • Cough
  • High Temperature
  • Aches and pains in joints – limping may be observed

It is estimated that around 80% of cat flu is caused by the FCV or FHV virus strains, however it can also be caused by bacterial strains such as Bordetella and Chlamydophila Felis. Bordetella also causes kennel cough in dogs and this strain has a high death rate in kittens.

Cats can be vaccinated against cat flu, but the vaccine will only provide protection against the viral strains; not the bacterial ones.

If your cat or kitten shows any of the symptoms described above, please seek veterinary treatment immediately.


Because it is usually caused by a viral infection, there is no cure for this illness, and it can be particularly challenging to treat. There are currently no effective antivirals that can be prescribed for this virus.

Your vet will be able to give you an initial diagnosis based on your cats’ symptoms, but they may run some blood tests or take swabs from your cat’s nose and/or mouth to send to the lab to identify the specific virus or bacteria.

If your pets’ symptoms are not life-threatening then your vet will probably prescribe good nursing care, like you would with a human who has a bad cold. They may prescribe antihistamines; nose drops and eye ointments.

  • You can remove the secretions from your pets’ eyes and nose regularly with some moist, soft cotton wool. These can sometimes stop your cat from being able to smell which in turn causes inappetence which can lead to dehydration. You can tempt them to eat with strong smelling foods such as warmed sardines or tuna.
  • You can place a drop of olbas oil on a wet flannel and place this over a radiator in the room your pet is being nursed in at home (NEVER APPLY OLBAS OIL DIRECTLY TO YOUR CAT!). 
  • Steam can help to clear congestion, so you can take your pet into the bathroom with you when you bath or shower (Be mindful that the cat does not jump into hot bath water!)
  • Keep your pet warm and comfortable and provide lots of TLC and cuddles.
  • Encourage your cat to drink, as fluids help to loosen thick catarrhal secretions.

Your pet will most probably not be hospitalised at this stage of the disease due to the risk of infection to other patients, but you should keep them separate from other cats in the household and ensure any person coming into contact with the cat adheres to good hygiene and washes hands, food bowls and litter trays regularly.

Antibiotics will not stop the FCV or FHP strain of the virus and will only be prescribed if your cat has a bacterial infection.

If your cats’ symptoms become more severe or they develop pneumonia, then they will need to be hospitalised for intravenous fluids and oxygen therapy.

Cats who have picked up the feline herpes virus display symptoms for 5 – 10 days; in more severe cases they can display symptoms for up to 6 weeks.

The FHV strain of virus can cause your cat to suffer ongoing health problems and they can become more susceptible to secondary bacterial infections. Cats with this strain are infected for life.

Cats diagnosed with the FCV strain are usually able to clear the infection within a few weeks and in some cases may show no signs at all; whilst others can develop pneumonia and painful mouth and nasal ulcers.

Long Term Consequences

Following infection, many cats are then left as carriers of the disease for the rest of their life. This means that, whilst they may not display symptoms, they can be a cause of a potential infection to another cat. This can be the reason that some kittens develop flu, when they are introduced into a household of “seemingly healthy” cats.

Some carriers may occasionally have a runny nose or eyes for a few days, others can be left with a lifelong runny nose which is known as ‘Chronic Rhinitis’. This is due to the delicate lining of the nasal passages being irreversibly damaged allowing for repeated bacterial infections to occur. Antibiotics can be prescribed by your vet to help alleviate the symptoms of this.

Calicivirus may cause long term inflammation of the gums, (chronic stomatitis), this can be a painful condition requiring long term medication and in severe cases extraction of multiple teeth.

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