Although known as cat flu, this condition is not caused by an influenza virus and is not transmissible to humans. There are many different viruses and bacteria which make up the ‘cat flu complex’ but they all cause similar signs such as sneezing, discharge from the nose, conjunctivitis (sore eyes), fever and lethargy. If the disease is severe, it has the potential to be fatal if left untreated. Some affected cats will never completely clear the virus and may be affected intermittently for their whole lives (known as cat flu carriers).
The two most common causes of cat flu are the viruses calicivirus (FCV) and herpes virus (FHV). The two most common bacteria are Chlamydophila felis and Bordetella bronchiseptica. The two main viruses are widespread among the cat population and can be transmitted by direct contact, sharing of air-space, or even on clothing. The disease can be fatal, particularly in young kittens, elderly cats, or cats whose immune system is not working properly (i.e. if they have feline leukaemia (FeLV), feline AIDS (FIV), or are on immunosuppressive treatment for another disease).
Signs of cat flu
Signs that can be seen include:
- sneezing, coughing
- discharge from the nose and eyes (can be severe)
- reduced appetite, or not wanting to eat at all
- severe lethargy
- ulceration of the tongue and eyes
- sometimes lameness can be seen
There is no specific treatment for cat flu. The main treatment is supportive care to give the cat the best chance of fighting it off themselves. Antibiotics may be required to prevent any secondary infection (which could lead to a life-threatening pneumonia). Severely affected cats may need intravenous fluids to treat dehydration and possibly a feeding tube to provide nutrition.
Cats rely on their sense of smell to give them an appetite and if their nose is blocked, this sense is reduced. Different ways to increase appetite include – using smelly foods such as oily fish, heating the food up to increase odours.
More recently, there has been some success with antiviral and interferon treatment in treating cat flu, particularly if caused by herpes virus. These are usually unlicensed treatments so your vet will need to go through the potential risks with you. They are also often quite expensive.
Prevention of cat flu
Vaccination against FCV and FHV is considered core (i.e. every cat should receive them). These vaccinations are usually combined with feline panleukopaenia virus vaccination and the primary course consists of 2 injections given 3 weeks apart with the last one being over the age of 12 weeks old. High risk cats should then be vaccinated annually. Lower risk cats (i.e. those who are indoor-only, single cats who never go to a boarding cattery) may be able to get away with only being vaccinated every 3 years. Speak to your vet about your own cat’s risk and decide on the best vaccination protocol for him.
Vaccinations against Chlamydophila felis and Bordetella bronchiseptica are also available but not considered ‘Core’. These should mainly be used in cats kept in large groups with a known risk (i.e. the disease has been previously confirmed). The Bordetella vaccination is an intranasal vaccine (drops of liquid squirted up the nose).