Feline Calicivirus (Cat Flu): Signs, Spread and Prevention

Urgent: if your cat stops eating or drinking, struggles to breathe, or has swelling, crusts or sores on the face or paws, contact a vet straight away. Kittens can get worse quickly [1][3][4].

Feline calicivirus (FCV) is one of the two main causes of "cat flu" [1][4]. It is very contagious between cats, but vaccination and good hygiene go a long way [2][5].

What is feline calicivirus?

• A highly contagious virus that affects cats [1].
• One of the two main causes of cat flu, together with feline herpesvirus [1][3][4].
• It usually causes a runny nose, sneezing and mouth ulcers [5].
• Some strains cause only fever and limping, and some cause no signs at all [5].

Can people or dogs catch it?

No. The virus is not known to infect people [1], and it is a cat disease only [5]. It is also not the same as "kennel cough" in dogs, which has different causes.

How does it spread?

• Mainly through direct contact with an infected cat's saliva, nose discharge or eye discharge [1][2][5].
• Through shared things: food and water bowls, litter trays, bedding and grooming tools [1][4].
• Sneeze droplets may play a part, but sources see this as less important than direct contact [1][4][5].

The virus is tough. It can survive on dry surfaces for up to about a month, though often for less [1][2][4][5]. Many ordinary cleaners don't kill it, so ask your vet which disinfectant works and how to use it safely around cats [2].

Can a healthy-looking cat spread it?

Yes. Some cats keep carrying and shedding the virus long after they recover, without showing signs [5]. In studies from Europe and North America, these "carriers" were much more common in groups of cats than in single-cat homes [5]. A cat can also catch a different strain again [5].

Which cats are most at risk?

• Kittens, especially as the protection from their mother fades [5].
• Cats in shelters, boarding catteries and breeding groups [2][5].
• Multi-cat homes where hygiene is hard to keep up [2].
• Unvaccinated cats, or cats behind on their vaccines [2][5].

Stress can also make a recovered cat start shedding the virus again [3].

What are the signs?

• Sneezing, a runny nose, eye discharge or red eyes [1][4][5].
• Fever, tiredness and loss of appetite [1][4][5].
• Ulcers on the tongue, gums, palate or lips, or drooling [1][4].
• Sudden limping in a kitten, sometimes moving from leg to leg ("limping syndrome") [2][5].

When should I see a vet?

See a licensed vet if you notice any of the signs above. Go urgently if:

• Your cat stops eating or drinking, or seems very unwell [3][4].
• Your cat has trouble breathing, especially a kitten [3][4].
• There is swelling of the face or legs, or crusts, sores or hair loss on the face, paws or ears [1][2].

These last signs can point to a rare, severe form called virulent systemic FCV. Reports from Europe and the US put the death rate at around 30–70% [1][2]. It is an emergency, not something to manage at home.

Is there a cure?

There is no home cure. Supportive care from a vet helps a sick cat recover, and your vet decides what that care should be [3][4].

How do I protect my cat?

Vaccination is recommended for essentially all cats; vets class it as a "core" vaccine [5][6]. It makes illness milder, but it can't fully stop infection or carrying the virus [2][4][5]. Kittens get a series of vaccines, then boosters as your vet advises [2][5].

At home:

• Keep new or sick cats apart from the rest until your vet says it's safe [1][2].
• Don't share bowls, litter trays or bedding between cats whose health you don't know [1][2].
• Keep groups small and stable, and reduce crowding and stress [2][5].

FAQ

Is feline calicivirus the same as cat flu?

It is one of the two main causes of cat flu. The other is feline herpesvirus [1][4].

Can my cat get it again after recovering?

Yes. Reinfection with a different strain is common [5].

Is it linked to long-term gum and mouth inflammation?

It is linked to it in some cats, but its exact role is not fully understood [5]. A cat with ongoing mouth problems should see a vet [5].

Do indoor cats need the vaccine?

Yes. It is a core vaccine for essentially all cats [5]. The virus can also travel on shared items [1][4].