What is Feline Calicivirus?

Calicivirus are members of the Caliciviridae family, and there are several strains which can infect cats.

80 - 90% of all feline respiratory disease complex  are caused by either feline calicivirus or feline rhinotracheitis virus (feline herpesvirus). Dual infection with both feline calicivirus & feline herpesvirus are fairly common. [1] Calicivirus usually affects the throat, eyes, nasal cavity & oral cavity in cats although sometimes the lungs & intestines are affected.

In the healthy adult cat, the mortality rate is fairly low, however kittens & older cats are at greater risk. Feline calicivirus is most often seen in shelters & environments with over crowding, although it can occur in any household.

There is a particularly virulent form known as 'virulent systemic feline calicivirus' with a mortality rate of 67%.

What is a virus?

A virus is a ultramicroscopic infectious agent which consists of either DNA or RNA wrapped in a protein coat. It is only able to replicate inside living cells. The phrase "a piece of bad news wrapped in protein" is a very well known saying regarding viruses.

Viruses are not living organisms, they don't respirate, process nutrients or generate waste products.

What are the symptoms of feline calicivirus?

There are several strains of calicivirus which infect cats, and symptoms differ depending on the virulence of the particular virus causing infection. Some strains may cause mild symptoms only, others severe.

Symptoms of calicivirus are often similar to that of a head cold in humans such as sneezing, nasal discharge, fever, rhinitis (inflammation of the nasal mucous membranes) runny eyes, salivation, ulceration of the tongue & palate are also regularly seen in cats with calicivirus. More virulent strains of calicivirus can cause pneumonia.

Calicivirus can also cause lameness in cats (known as limping syndrome). This has been seen in not only naturally occurring calicivirus but also after vaccination. [2]

Feline calicivirus can be complicated by secondary bacterial infections, anorexia & dehydration.

Feline calicivirus has been observed in the mouths of some cats with gingivitis.

How do cats become infected?

• Direct contact: Infection is passed from an sick or carrier cat via eye, nasal & mouth discharges.
• Indirect contact: Contaminated food bowls, bedding etc. Calicivirus is resistant to many disinfectants & can live in the environment for long periods of time.
• It is possible for cats to remain carriers for years after infection. This means even though they have contracted the virus, become sick & recovered, the virus is still being shed in excretions & it is possible to infect other cats.

How is feline feline calicivirus diagnosed?

A presumptive diagnosis is usually based on clinical signs in the cat. As stated earlier in the article, feline herpesvirus & feline calicivirus account for 80 - 90% of all feline respiratory disease complex.  If oral ulcers are present, calicivirus is most likely.

If corneal ulcers are present (eyes), herpesvirus is most likely.

How is it treated?

Treatment is generally supportive. As calicivirus is a virus, antibiotics won't work, however they may be prescribed for secondary bacterial infections.

Removal of discharge from the nose & eyes will make your cat more comfortable.

If the cat has become anorexic, force feeding may be necessary. Fluids may also be required to treat dehydration.

Prevention of feline calicivirus:

Routine vaccination.

Avoiding overcrowding of feline populations, reducing stress.

Can I catch feline calicivirus from my cat?

No, it is not possible for humans to become infected with feline calicivirus.

Further Reading:

Cat Flu

References:

[1] The Merck Veterinary Manual

[2] Cat Lovers Vet