We humans all know what it feels like to come down with the flu. We’re all familiar with sick days spent sneezing and feverish in bed, cranky and without any appetite. But just like us, our feline friends have their own version of the flu, and as cat owners, it is important for us to know the causes, symptoms, and prevention of this virus.

“Cat flu” is the general name for upper respiratory tract infections in cats. The cat flu is caused by two kinds of viruses, which are feline herpesvirus (FHV-1), and feline calicivirus, also known as FCV. We’ll be focusing on the latter as columnist Stef dela Cruz nearly lost her new furbaby to this disease.

While cat flu is seldom fatal in previously healthy cats, those who weren’t healthy to begin with, or young kittens are vulnerable and could die from FCV.

If your cat catches the virus, he or she will need a lot of TLC. Keep them warm, feed them soft, strong-smelling food (the smell will entice them to eat), and take him or her to the vet if s/he stops eating or drinking. You’ll also need to quarantine him or her from your other cats to prevent the virus from spreading and taking its toll on humans (who will be tired out from nursing sick kitties) and felines alike.

What is FCV?

FCV, or feline calicivirus, is a highly contagious virus that spreads through direct contact with bodily fluids, inhalation of airborne sneeze droplets, sharing of food bowls and litter trays, or a contaminated environment. FCV spreads quickly in animal shelters or within multi-cat homes. Cats housed in large numbers or kittens with weak immune systems are especially susceptible.

Cats infected with FCV can carry the virus in their bodies for life. An estimated 10% of household cats are such carriers, and may become sick again during times of stress or illness, although many will not. They can even continue to shed the virus, putting other cats in their vicinity at risk of infection.However, over half of infected cats eliminate the virus after 2-3 months, and most cats eliminate it completely after 18 months.


The most common symptom of FCV is ulceration of the mouth and tongue (known as stomatitis), palate, lips, and tip of the nose. The cat may also be suffering from gingivitis. All of this can make it painful for the poor kitty to eat, leading to loss of appetite.The cat may be depressed or lethargic, and might also be running a fever. Some strains of FCV even cause ulcers in the paws, or joint pains that can cause a limping syndrome in cats, affecting first one leg, then another.

FCV also causes cold-like symptoms like runny nose and discharge from the eyes, known as conjunctivitis. This results in mucus buildup that can dry to a crust. You can wipe away the mucus with a warm, moist cloth. A cat may also resort to breathing through its mouth when its nasal passages get blocked with mucus and swell. These symptoms typically last for about 7-10 days. Sometimes a cat may develop secondary bacterial infections that can lead to pneumonia.

But don’t make your own diagnosis based on this article or on Internet research alone. Always take your sick cats to the vet, who will make the diagnosis based on symptoms, and may also send a swab of the cat’s throat to the lab for testing, to check specifically for FCV.


Unfortunately, like all viral infections, there is no specific treatment for FCV, although your vet may prescribe antibiotics to fight secondary bacterial infections. Fortunately, the cat flu is seldom fatal in previously healthy cats (please note that this won’t apply to cats who aren’t healthy to begin with, or young kittens whose immune systems aren’t fully developed yet), although they will need intensive nursing and support, particularly keeping them warm, and feeding them soft, strong-smelling foods like sardines, to minimize the pain from their mouth ulcers and to entice them to eat.

Your vet may prescribe eye drops or ointment to treat your cat’s conjunctivitis, and its eyes and nose should be kept clear by bathing frequently with warm, soapy water.If your cat stops eating and drinking, consult your vet as soon as possible. Hospitalization may be necessary, and cats may need to be force-fed or put on intravenous fluids, which will require a couple of days’ stay at the vet’s. This is especially important for multi-cat households as quarantine may be necessary to prevent the infection from spreading to other cats.


Just like our own human colds, there may be no way to completely prevent your furry friend from catching a cold or upper respiratory infection. However, there are steps we can take as loving cat owners to minimize the chances of catching FCV.

Always provide your cats with the best quality food you can afford, with real protein as the main ingredient, to ensure the proper nutrition necessary to maintain a healthy immune system.Make sure your cat’s living space is clean. Clean your floors with a mild bleach solution, which kills viruses on hard surfaces. Pay close attention to the cat’s food bowl, water dish, and litter box.

Finally, keep your cat’s vaccinations up to date. FCV vaccine is among the core vaccinations recommended by veterinarians to all cats. The thing is, FCV is an adaptable virus, and there is no vaccination that provides 100% protection.

The good news is that cats infected with FCV can eliminate the virus from their systems, given time and good care. Prevention is the best solution; since your cat is low-maintenance anyway, why not invest in its shots?

However, even if vaccinated cats can still catch the virus and become carriers, they have a lower chance of spreading the infection, and experience milder symptoms, than unvaccinated cats. 2-3 injections are recommended for kittens, starting at 8 weeks of age. Cats should receive their booster shot when they reach 1 year, and should get further booster shots every 1-3 years.

Virulent FCVA virulent strain of calicivirus was first reported in 1998 in Northern California, and since then this strain, mostly reported in the United States, has been called “virulent systemic feline calicivirus” or VS-FCV, although since some of these strains appear to be arising independently, it is misleading to label them under a single name. This particularly nasty strain has a mortality rate much higher than the usual variety, up to 67%. Fortunately there have been fewer than 20 documented outbreaks, and a new vaccine is now available.

This appeared in Animal Scene’s February 2016 issue.