Feline Calicivirus (FCV)

What is calicivirus?

Feline calicivirus, or FCV, is an oral and upper respiratory virus that can be spread by cats or humans in close contact with cats. Spread primarily through a cat's bodily fluid, it is one of the most prominent causes of upper respiratory infections (URIs) in cats, alongside feline herpes (FHV).

Feline calicivirus symptoms

As we've mentioned, Feline calicivirus causes upper respiratory infections (URIs) in kittens and cats. This secondary infection is responsible for the majority of symptoms including:

• Nasal discharge
• Congestion in the respiratory tract
• Sneezing
• Ocular (eye) discharge
• Mouth ulcers
• Loss of appetite
• Lethargy

It is a naked virus, which means it is relatively resistant in the external environment and is difficult to remove. After infection, it may take anywhere from a few weeks to a few months for a cat to fully recover.

What is the difference between FCV and FHV?

While FCV is primarily an oral disease affecting the nose and mouth, the feline herpesvirus (FHV) affects the eyes in the form of conjunctivitis and corneal ulcers. However, both viruses have been known to impact all three (nose, mouth and eyes).

These two viruses are quite different, but sometimes get confused as they're often involved in "cat flu," which is a syndrome characterized by eye infections (conjunctivitis, discharge), nasal discharge, mouth inflammation, and ulcers.

How to diagnose FCV

To find out if your kitten has FCV, they'll need to be diagnosed by your veterinarian. They'll observe your kitten for symptoms (as listed above) and may offer treatment based on these observations alone. However, they may also take swabs from your kitten to test for the presence of the virus. A positive test result, however, does not always mean your kitten is sick. It may mean they have had the virus in the past but there is no active infection.

Treatment for calicivirus

Prevention is the best form of treatment, so always ensure your kitten is fully vaccinated and receives boosters when recommended as they grow into adult cats. There is currently no cure for the virus, but your veterinarian may offer the following treatments to ease the symptoms of an infection:

• Pain medication: If their symptoms are causing discomforting pain
• Antibiotics: To prevent and treat further upper respiratory tract infections
• Anti-inflammatories: To reduce inflammation and fever as a result of infection
• Eye drops: If your kitten has developed eye discharge as a result of an infection

How long does calicivirus last?

Your kitten may recover from calicivirus any time between 7 days and 3 weeks, depending on the severity of the infection. If they become a long-term carrier of the virus, however, they may still be able to infect other cats months after they have recovered from their initial infection.

Can my kitten recover from FCV?

Feline calicivirus exists in a wide variety of strains, meaning a cat can get infected many times throughout their life, in a similar way to humans picking up a common cold time and again.

It's a common misconception that cats will never rid themselves of FCV once first infected. In fact, in the case of a first infection, a vulnerable cat like a kitten may or may not develop symptoms. After initial infection, they may continue to shed the virus for a few weeks to several months, but in most cases ultimately recover. This is particularly true if the animal lives alone and is not re-infected.

For cats living together, the problem is that the virus circulates, and cats are re-infected constantly (either via contact with other cats or via the contaminated environment, since the virus is resistant in the external environment).

Always remember: A kitten or cat that lives alone and is infected with calicivirus should be able to completely eliminate the virus after a period of a few weeks to a few months.

Are there any side effects for kittens suffering with FCV?

FCV can have dramatic consequences for cats, especially kittens, as it affects their ability to eat. Smell is a vital part of a cat's relationship to food. Unfortunately, respiratory tract infections can mean kittens get congested airways, a blocked nose and will refuse food. Painful lesions and ulcers in the mouth can be another reason your kitten may avoid food if they have FCV.

How is FCV spread?

FCV can be spread in the following ways:

• Directly between cats
• Humans stroking cats and not washing their hands

Objects that come into daily contact with an infected cat such as food bowls, cat carriers, and brushes must also be cleaned regularly to stop the infection from spreading.

Can my kitten be exposed to FCV when in contact with other cats?

Your kitten could still be exposed to the virus when in contact with other cats that appear healthy.

An animal showing no signs of any illness may actually still be carrying some diseases including feline calicivirus. This healthy carrier may represent a risk for other members of the community, especially kittens.

Can a cat with calicivirus live with other cats?

Calicivirus is a highly contagious oral disease and may be contagious even when your kitten seems healthy. However, the chance of infection gets much lower after your kitten recovers from the initial virus. If your non-infected kitten had a full dose of the FVRCP vaccine and gets their boosters, it is still possible for them to live with an infected cat.

Can dogs get calicivirus from cats?

No, dogs cannot usually catch calicivirus from cats, it can only be passed between other cats.

Can humans get calicivirus from cats?

No, humans can not catch calicivirus from cats. It is not a zoonotic virus and therefore can not be passed between cats and humans. Although humans cannot be infected, they can pass the virus to other cats through contact with infected animals.

How long does it live on surfaces?

Calicivirus is a highly contagious virus, primarily because of how long it is able to last on surfaces. Once discharged from an infected animal, it can last up to 2 weeks on a surface. As a result, it's important in any home or professional environment where many cats socialize, to clean and disinfect common areas.

How long is it contagious?

Cats are at their most infectious during the incubation period of the virus, which is between 2 and 14 days after they are first infected. They are, however, still highly infectious at least 3 weeks and up to 6 weeks after infection. If cats become long-term carriers, this period of contagiousness can last even longer.

How can I prevent my kitten from picking up feline calicivirus?

Ensuring your kitten is vaccinated helps prevent contagious diseases, including FCV. Vaccines are split into two types: "core" and "non-core".

The core vaccinations for kittens include:

• Feline calicivirus (FCV)
• Feline panleukopenia virus (FPV)
• Feline herpes virus (FHV-1)
• Rabies virus (RV)

Vaccinations are most effective when they are given on fixed dates with booster vaccinations at specific times. However, there are many different strains of FCV and vaccines only cover some of these strains. So even if the cat is vaccinated they might develop FCV.

When should my cat be vaccinated?

The American Animal Hospital Association recommends that kittens receive their initial FVRCP vaccine (which covers FCV, FPV and FHV-1) no earlier than 6-8 weeks of age. Speak to your veterinarian, who will be able to assess the cat's risk profile and the best age to be vaccinated.