Feline Calicivirus

All cats and kittens over 12 weeks old must be vaccinated before coming into our care

Feline calicivirus (FCV) is a worldwide problem. It is one of the most common causes of upper respiratory infections, or flu, and oral disease in cats.

What are the symptoms?

The typical signs of an upper respiratory infection involve the nose and throat such as sneezing, nasal congestion, loss of appetite, lethargy conjunctivitis or inflammation of the membranes lining the eyelids, and discharge from the nose or eyes. The discharge may be clear or may become yellow/green in colour. In addition to these typical symptoms, cats with a calicivirus infection often develop ulcers on their tongue, hard palate, gums, lips, or nose. These cats will usually salivate or drool excessively as the ulcers are very painful.

Some strains of calicivirus may cause an infected cat to develop sudden painful lameness in one or more joints; this lameness occurs more frequently in kittens.

On rare occasions, a mutated form of the virus can be severe, resulting in severe disease including pneumonia, hepatitis (liver inflammation), pancreatitis, skin swelling and ulceration, and bleeding from the nose and intestine. Up to two-thirds of cats infected with this mutant virus will unfortunately die.

How is it transmitted?

Calicivirus is highly infectious and can be transmitted from cat to cat in the following ways:

• through contact with saliva or secretions from nose or eyes;

• through inhalation of the viral particles from an infected cat’s sneeze. When a cat sneezes, particles can be sprayed several metres through the air;

• through sharing food bowls, toys and litter trays;

• from a contaminated environment including bedding and grooming equipment;

• from people who have touched contaminated objects or an infected cat.

There is some suggestion that the virus may also be passed in urine or faeces, but if so, this isn’t thought to be a major source of infection.

The virus can potentially survive for up to one month in the environment, but probably does not survive for longer than 4-14 days. The damper the environment, the longer it is likely to last.

Although all susceptible cats may develop a calicivirus infection, symptoms tend to be more severe in young kittens.

Calicivirus is very species specific and does not represent any risk to people or other species of animals.

How long is a cat infectious to other cats?

Once a cat is exposed to calicivirus, it will go through an incubation period of 2-6 days before developing signs which typically last for 14-21 days. During this entire time, the cat will potentially be infectious to other cats. At a minimum, infected cats will pass on the virus in their bodily secretions for 2-3 weeks.

Following apparent recovery from the disease, as many as half of all infected cats may develop a carrier state in which they will continue to pass on the virus. In some of these cats the carrier state may only last for a few months, but in a small percentage, the carrier state may persist for life. Carrier cats may or may not show any signs of infection when they are actively passing on calicivirus and are an important source of infection to susceptible cats. Female cats that are carriers of this virus can pass the infection on to their newborn kittens.

You should seek advice from your vet urgently if you suspect your cat may have the calicivirus.

How is it treated?

Most cats with an uncomplicated calicivirus infection can be treated at home. Your vet may prescribe an eye medication to be applied topically if your cat has a eye discharge. Antibacterial drugs may also be prescribed to try to prevent secondary bacterial infections, particularly in kittens.

Cats with nasal or airway congestion may benefit from increased humidity - a steamy bathroom for example. To minimize irritation from eye or nose discharges, you should try, where possible, to wipe them away from your cat's face with a moist tissue.

Since cats with a respiratory infection will have a decreased sense of smell, feeding a slightly warmed, particularly smelly canned or sachet food may encourage them to eat.

In severe cases, a cat may need hospital treatment in the form of intravenous fluid therapy and other supportive treatments.

What can we do to stop the virus spreading?

If a cat is part of a multi-cat household any of them showing signs of the virus should be isolated if at all possible, and strict hygiene should be ensured. Contaminated objects can be disinfected by soaking them for at least 10-15 minutes in a solution of bleach and water (1 part bleach to 32 parts water). Feeding bowls, litter trays, implements, gloves etc should be separated.

And as people can pass the virus from one cat to another careful washing of hands is essential.

How can calicivirus infections be prevented?

Vaccination is essential.

Since calicivirus is a highly infectious disease and apparently healthy cats can be carriers of it, it can be difficult to prevent your cat from exposure to the virus. Boarding facilities and animal shelters are all places where cats can be readily exposed to calicivirus. Cats that are unvaccinated, are young, or have chronic underlying problems are more susceptible and may develop a serious illness if they contract the virus.

The standard vaccinations that are given to cats include immunization against calicivirus. While these cannot prevent it completely due to the various strains of the disease, they will help reduce the severity of disease and shorten the length of the illness if your cat is exposed.

Two or three injections are recommended in kittens between the ages of 8 and 16 weeks, and at least one other booster a year later. After this initial series, the cat will also need a booster every 1-3 years.

For most strains of calicivirus, adult cats that are more than 3 years old, or cats that have been adequately vaccinated will likely only develop a mild case of illness, for which the cat may not even need veterinary treatment.

One final piece of advice, it is always wise to isolate a new cat from other cats in your household for at least 1-2 weeks to minimize transmission of calicivirus or any other infectious diseases.