Published by: Ingrid King. Last Updated on: November 1, 2022 by Crystal Uys


Feline calicivirus, or FCV, is a viral infection causing severe upper respiratory problems in cats. Entering through the cat’s eyes, nose, or mouth, this virus possesses symptoms similar to that of a common cold. As loving cat owners, it is important to be well informed of the causes, symptoms, and prevention of this fast-spreading infection to help keep our feline friends happy and healthy.

Frequently seen in animal shelters or within multi-cat homes, the FCV infection is typically spread amongst cats that are being housed together in large numbers or kittens with weak immune systems. Once the cat is infected with FCV, they may carry the virus in their bodies for life. “Approximately 10% of household cats exhibit this ‘carrier’ state and have the chance of becoming sick again during times of stress or other illness, although many will not” said Dr. Kathy Scott, lecturer at the College of Veterinary Medicine & Biomedical Sciences. “They may continue to shed the virus, however, putting other cats they are near at risk of developing the infection.”

Depending on the strain of the virus, infected cats can show a great variety of symptoms. Typical symptoms seen with FCV are similar to an upper respiratory infection, involving sneezing, nasal congestion, and conjunctivitis, with more severe cases exhibiting lethargy and poor appetite as well. “Some cats will develop severe gingivitis and oral pain that may be significant enough to cause the cat to not eat, while others may demonstrate lameness and fever,” Scott said. “Rarely, a severe variant of calicivirus (called FCV-associated virulent systemic disease or FCV-VSD) can develop and cause critical illness, multiple organ damage, and even death.” Luckily, this form is very rare and outbreaks can be controlled through strict isolation and quarantine.

Accurate diagnosis will help your veterinarian provide the best treatment possible, and is also important if the infected cat lives in a multi-cat household.. To diagnose FCV, the vet will evaluate the cat’s clinical symptoms and medical history in addition to laboratory testing. “A swab can be taken of the cat’s mouth or conjunctiva (a thin membrane of the eye), and tested for presence of the virus in those tissues,” Scott said.

Unfortunately, the treatment of FCV is challenging. There are currently no medications to completely eliminate the virus or eliminate the infection at a faster pace, so the best thing you can do for your furry friend is to provide them with the support and care they need to help them feel comfortable. Due to their stuffy noses and possible ulcers in their mouths, cats with FCV have a tendency to lose their appetite, so it is wise to provide them with soft, strong-smelling foods or pain medications that will make eating more comfortable. “We also recommend keeping their noses clean and sometimes using medications or vaporizers to help loosen the mucus in their noses, making it easier to breathe,” Scott said. “In more severe cases, antibiotics may be needed to stop the growth of bacteria that have overgrown as a result of the FCV infection, and if cats haven’t eaten in more than three days, they will probably require a short period of hospitalization to receive fluids and some form of nutrition.”

The most important measure you can take to reduce the likelihood of your cat contracting FCV is to ensure that their vaccinations are up to date at all times. “Although there is no vaccination that provides 100% protection, there is a vaccination available for FCV, and it is part of the ‘core’ vaccinations recommended by veterinarians to all cats,” Scott said. “This vaccine is likely to decrease risk of the development of upper respiratory infection, but, unfortunately, can’t protect against all strands of FCV, so cats still may become infected.” Though vaccinated cats still have a chance of becoming carriers if infected, they do have a lower chance of spreading the infection to other cats than those that are unvaccinated.

If coming down with an upper respiratory infection is miserable for us, imagine what it is like for our cats. Taking precautionary measurements to prevent them from coming down with FCV, as well as keeping an eye out for specific symptoms, can make a world of difference for both you and your feline friend.

This article is reprinted with permission from the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University.

Editor’s note: Sadly, I have had personal experience with the virulent version of this calici virus. In May of 2013, Amber contracted this virulent from of the virus, and she passed away less than two weeks after she started to get sick. At my request, her veterinarian at the time, Dr. Fern Crist, wrote a post about Amber’s progression for me in hopes of making cat guardians and veterinarians alike more aware that mutant caliciviruses are capable of creating disease scenarios such as Amber’s, and that this may be more common than we realize. Read Virulent Feline Systemic Calici Virus for more information.

Photo ©Robin Olson, Covered in Cat Hair, used with permission.

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13 Comments on Feline Calicivirus: Not Your Common Cold

  1. Our newest kitty Charlie unfortunately has this virus, we confirmed this at the vet and they had him do two rounds of antibiotics. His nose and eyes have cleared up but as you say it doesn’t completely go away, we’ve noticed he’s often a little sniffly and sneezy especially when he has been sleeping. Fortunately our other cats are vaccinated and we kept him away from them while he was sick and took all usual precautions e.g. washing hands after handling him etc. So we are hoping for the best.

      • Hello Ingrid,
        I’ve been looking for any comments about boosting a cats immune system to fight off returning symptoms of Feline Herpes. I’ve already gone the route of antibiotics and a few other medicines and my cat has greatly improved but she’s still sneezes and has a runny nose which dries up during the night making it difficult for her to breathe. I’d love to hear about what might bring a cat to the point where they can fight back these last symptoms. Thanks very much.

        • Here are some tips to boost your cat’s immune system, Susan:

  2. I took in a stray cat back in January, turns out he has FCV. He has been living in our bathroom since we found him because he was sick and I have 5 other cats. Now that we know what he has I am very worried about our other cats getting it. One of our cats has feline herpes virus and I am pretty sure she has it now she is starting to show the same symptoms, but our other cats are not showing signs. We are going to get their vaccine updated on Sunday but I am still worried about them getting it. Do you have any experience with FCV cats living with other cats? I am so scared that my other cats will get FCV but I wasn’t able to rehome the one I found, no one wanted a sick cat and I have now fallen in love with him, but if all my other cats get sick I will feel so bad. I already feel horrible that my cat who has the herpes virus caught it, but I am hoping she only got it because she has a weaker immune system due to the herpes virus compared to the other cats.

    • FCV is always contagious. As you’re already seeing with your cat, it depends on how strong a cat’s immune system is whether they will get sick from it or not.

  3. Thanks for this post. I have one kitty that always gets colds and I thought I was going to lose him at the begining of the year. This is the second time in his life he got real sick like this. I wonder if he has something like this. I will have to ask my vet about it. Sorry for the lose of your kitty Ingrid.

  4. Ingrid I wonder if this is what is going on with the cats at Brian’s Home? (all of his cats are sick right now). I am afraid to share this with him because of the part about your kitty having passed from this. I do feel he should see this though. 🙁

    • Caren, I just took a look at Brian’s site, and it sure sounds like that’s what his cats are sick from. Amber had the virulent form of the virus, and it’s something many non-shelter vets don’t readily think of, so you may want to let Brian know to ask his vet about VS-FCV.

  5. Unfortunately our shelter sees this virus multiple times a year since we are open admission. It’s awful when the cats have nose & mouth ulcers and don’t want to eat. Fluids, nebulizing, antibiotics, and lots of TLC have helped.

    • This is a tough virus to keep out of shelters, and to keep from spreading, Laura. I hope you never see the virulent form of it!

  6. thank you for this info , came across the word calicivirus an wanted to know what it was , thanks so much , sorry to hear one of your cats got it , take care .

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