THE simple answer to this is no! Although the vast majority of cat breeders and cattery owners recognise the importance of vaccination’s role in preventative healthcare, the fact remains that a significant proportion of cats in the UK are unvaccinated. This alone is a major reason for the continued incidence of feline respiratory disease in this country.

It’s a fact that cat ’flu remains a depressingly common experience amongst breeders and cattery owners. The disease can vary in severity, with kittens and entire litters particularly at risk. Animal health company, Intervet UK, has delved deeper into the problems associated with cat ’flu and offers breeders and cattery owners some practical advice on control, vaccination and management.

Despite the name, the causes of cat ’flu bear no relation to those of human influenza. Whereas influenza is caused by a single virus, cat ’flu is a syndrome with signs of disease caused by one or more pathogens, both viral and bacterial.

There are three known primary pathogens involved in the cat ’flu complex, namely feline herpesvirus (FHV), feline calicivirus (FCV) and Bordetella bronchiseptica. Both of the viruses that cause cat ’flu can only occur in members of the cat family. Bordetella bronchiseptica, on the other hand, can cause disease in a range of species, and is the principal cause of kennel cough (infectious tracheobronchitis) in dogs.

The “carrier state”

Animals that become infected with any of the agents responsible for cat ’flu may continue to be a risk to other cats, whether or not they show signs of the disease. Therefore, this “carrier state” will be a factor regardless of which infectious agent is responsible.

All cats infected with feline herpesvirus (FHV) are typically infected for life. Following infection, the virus will become “hidden” (or “latent”) and the cat will show no immediate signs. However, following a stressful event (car journey, cat show, etc), these latently-infected individuals may start to shed infectious virus again. These periods of shedding may or may not be associated with signs of cat ’flu. In other words, some are healthy looking or “silent” shedders and it will not be immediately obvious that these individuals present an infection risk.

Unfortunately, FHV carriers are difficult for vets to spot since samples taken from cats for laboratory analysis rarely identify latent infections. Because of this, the true incidence of herpesvirus carriers in the UK is unknown.

Cats that are infected with calicivirus tend to shed the virus continuously for weeks, months or even years; therefore carrier cats are easier to identify. Most cats will stop shedding the virus eventually, but a minority do become persistent shedders. In recent years, some cats with chronic gum inflammation (gingivitis/stomatitis) have been shoen to be persistently infected with calicivirus.

Carrier cats are also important with respect to Bordetella bronchiseptica infections. This bacterium has been shown to persist in cats for at least 19 weeks after infection, but the upper limit is still not known. It could be that tests are simply not sensitive enough to detect all carriers (for example, infected queens have been shown to have “recovered” enough to produce a negative swab test, and then later begin to shed Bordetella again due to the stress of pregnancy and kittening).

 

• Cat ’flu is caused by both viruses and bacteria.
• Too few cats are vaccinated and ‘carriers are common, so the disease is still rife.
• Quarantine new cats and keep cats in groups of three or less if possible.
• Regularly disinfect rooms, equipment - and your hands!
• Vaccinate against Bordetella as well as herpes and calicivirus.

 

This is particularly worrying in view of the potential severity of the disease in young kittens. Unfortunately, whilst antibiotics may have an effect in reducing the signs of Bordetella infection, they do not deal effectively with the carrier state.

Risk reduction

Without doubt, vaccination plays a vital role in the protection against cat ’flu. However, the fact that we know that a significant proportion of the feline population is not vaccinated, consideration must be given to other ways of reducing the risk of infection.

In terms of the spread of infection, susceptible individuals become infected from direct contact with cats showing signs of the disease. But infection can also occur from a contaminated environment - all cat ’flu pathogens can survive for a limited time outside the body. Airborne infection may also occur, so good draught-free ventilation is very important.

Similarly, consideration should always be given to the size of the group. Large numbers of cats provide optimum conditions for the spread of cat ’flu infections. From a purely disease-control point of view, keeping cats individually is ideal, though this is not always practical or desirable in a breeding household. Failing this, cats in smaller groups of say three or less should reduce the opportunity for infection to spread.

Strict isolation and quarantine is paramount for any new cats introduced into the establishment, simply because the stress of re-homing may trigger clinical disease and/or virus shedding in a cat that carries herpes virus. Clearly, those cats at high risk, e.g. queens with young kittens, will also benefit from rearing in strict isolation ideally in a separate kittening room. ‘Barrier nursing’ is required to prevent cross-infection into such an environment, however, even this will not be enough to prevent disease in the kittens if their mother is a carrier.
Breeding from queens that become persistent carriers of infection is likely to lead to infection in their kittens, causing serious disease. Practical advice does differ, but options may be limited. Specific advice from your veterinary surgeon should certainly be sought in these circumstances.

Cleaning and disinfection

Any cat can potentially be a carrier, therefore any used accommodation should be regarded as contaminated and a potential source of infection. Cleanliness of accommodation is imperative - luckily both the viruses and indeed, Bordetella are susceptible to the common disinfectants recommended for cattery use.

However, bacteria and viruses do survive, particularly within organic debris such as discharges and faecal matter. Therefore, cattery accommodation needs to be designed so that it is easy to clean and disinfect. For example, an easy washable surface such as a Perspex “sneeze barrier” not only provides a physical barrier, but is also easier to clean than wire mesh.

When cleaning the accommodation, don’t forget everyday objects such as toys, feeding bowls, water dishes and carrying baskets because these could carry infection. Similarly, try and keep these items within the same group of cats. Also remember that human hands, clothing and footwear may also carry infection. Hands should be washed frequently with an anti-bacterial wash, while protective clothing and overshoes should also be considered when handling different cats.

In terms of virus survival, herpesvirus lasts for up to 18 hours, whilst calicivirus, which is much hardier, can survive for up to seven days or even longer in damp conditions. However, because none of the cat ’flu agents last for extended periods, time is often an ally, particularly if you can allow the cattery accommodation to stand empty for a period of time before re-using.

Vaccination strategies

For kittens, it is recommended that the primary course vaccination for calicivirus and herpesvirus is often commenced at nine weeks of age. This is timed to coincide with the decline in the antibodies received from the mother’s milk (which might otherwise interfere with vaccination). Two doses should be given three to four weeks apart, and to maintain maximum protection, annual boosters are recommended.

A vaccine for Bordetella bronchiseptica is also now available, called Nobivac Bb for cats. This is particularly suited for young kittens at risk of respiratory disease. The vaccine is simply administered as drops down the nose from as early as four weeks of age. This is probably the most appropriate timing for administration to kittens in an at-risk breeding environment because it is before the time of highest risk of disease.

Annual re-vaccination against Bordetella is advised when the adult cats are considered at risk, including those remaining within or visiting a multicat environment (breeding, boarding and rescue catteries) as well as individuals that live with dogs.

The risk of Bordetella disease in cats that are kept alone, or in groups of three or less, is low and revaccination of these individuals would not be advised unless they are exposed to the above risks.

For those breeders and cattery owners that are interested in finding out more, Intervet has produced an informative guide entitled ‘How to control cat ’flu’. Copies are available via Intervet’s Veterinary Support Group on 01908 685685.