Cat' Flu

Cat 'flu remains a depressingly common experience, despite the important contribution made by vaccines. The disease can vary in severity, but kittens are particularly at risk and entire litters have been known to die soon after contracting it.

Who is at risk?

Cat 'flu is most commonly seen in situations where cats are kept in large groups such as breeding catteries, rescue centres and feral cat colonies, although it can also be seen in pet cat households. Cats most at risk include unvaccinated cats, kittens, the elderly and cats which are immunosuppressed for any reason.

Causes and symptoms

Despite the name, the causes of cat ‘flu bears no relation in those of human influenza. Whereas influenza is caused by a single virus, cat ‘flu is a syndrome: the signs of this disease may be caused by one or more of several different infectious agents (pathogens). Symptoms include sneezing, nasal discharge, conjunctivitis (inflammation of the lining of the eyes), discharge from the eyes, loss of appetite, fever and depression. Occasionally, mouth and eye ulcers and excessive drooling of saliva may be seen. The very young, very old and immune suppressed cats are more likely to develop severe disease and possibly die as a result of their 'flu.

There are primarily three known primary pathogens, capable of causing cat ‘flu on their own. These are feline herpesvirus (FHV), feline calicivirus (FCV) and the bacterium Bordetella bronchiseptica. Respiratory disease problems within a household or cattery environment may involve one or more of these infectious agents.

Feline herpesvirus (FHV)

Although the majority of cats infected make a full recovery, this often takes several weeks and some cats are left with permanent effects of infection such as recurrent eye problems and chronic rhinitis (inflammation of the nose). Cats with chronic rhinitis are usually well in themselves but have a persistent discharge from the nose. Secondary bacterial infection of damaged tissue can cause chronic conjunctivitis, sinusitis and bronchitis (inflammation of the linings of the eyes, sinuses and air passages). Antibiotic treatment usually only provides temporary relief of these symptoms.

Herpes carriers may come down with cat ‘flu (clinical signs and viral shedding) following stressful events, like staying in a cattery, many months after first catching the disease.

Feline calcivirus (FCV)

Infection usually causes a milder form of cat 'flu with less dramatic nasal discharges. Characteristic mouth ulcers are sometimes the only sign of infection. The ulcers may be present on the tongue, on the roof of the mouth or the nose. Some strains of FCV cause lameness and fever in young kittens. Affected cats recover over a few days although they may benefit from pain killers at this time.

Calicivirus carrier cats shed virus continually with most cats eventually becoming carriers, but some are persistently-infected – sometimes this is associated with mouth inflammation (gingivostomatitis).

Bordetella bronchiseptica (Bb)

This infectious bacterium is more commonly known as the most important cause of canine infectious tracheobronchitis (Kennel Cough). However, this bacteria also causes respiratory signs in cats that can be hard to differentiate from cat ‘flu caused by viral infections. Bordetella can be a particular threat to young kittens and occasionally whole litters of kittens may be lost to this infection.

Cats that recover from cat ‘flu are often unable to completely eliminate the viruses or bacteria from their body and many become “carriers”, able to transmit the disease to other cats for years.

How is it spread?

The cat ‘flu viruses and bacteria are relatively sturdy and can survive in the environment for several days. They are spread through direct contact with an infected cat showing signs of 'flu or disease, from direct contact with a contaminated environment (eg: clothing, food bowls and other objects) and from contact with a cat that is a carrier of cat 'flu (that may or may not be showing signs of disease).

Prevention and control

The risk of developing cat 'flu can be reduced by regular vaccination against FHV, FCV and Bordetella bronchiseptica.

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