By Jennifer Copley (Last Updated 12 February 2011)
Feline Calicivirus (FCV) is a common cause of upper respiratory infection (otherwise known as cat flu or cat cold).
Feline Calicivirus Symptoms
Symptoms of FCV in cats may include:
- Appetite loss
- Congestion/difficulty breathing/open mouth breathing
- Eye discharge/red eyes/eye ulcers
- Limping (due to arthritis or myalgia)
- Paw ulcers
- Runny nose/sneezing
- Sores on the lips, tongue, or nose
Kittens and adult cats with compromised immune systems tend to have more severe symptoms, and cats afflicted with FCV often develop pneumonia as well.
There is also a rare strain of Calicivrius called Virulent Systemic Feline Calicivirus that causes more severe symptoms, including swelling, high fever, skin lesions, diarrhea, and vomiting, in addition to the regular FCV symptoms. The more severe strain is often fatal.
How Cats Catch FCV
Cats usually catch FCV via nose and mouth secretions, so sharing food bowls, mutual grooming, and touching noses are common modes of transmission. Cats that live in crowded or unsanitary conditions are more prone to catching FCV.
Humans may also transmit the virus from one cat to another if they touch an infected cat and don’t wash their hands thoroughly before interacting with another cat. FCV is quite resistant to disinfectants and requires a solution of 1 part bleach to 32 parts water to kill it on surfaces.
The initial FCV illness typically lasts for just 7-10 days, but most cats remain carriers of the virus for months or even years afterward and can spread it to other cats (approximately half of all infected cats stop shedding the FCV virus at some point, whereas the rest carry it for life). Humans and other animals can’t catch FCV from cats, however, so there’s no need to quarantine an infected cat away from people and non-feline pets.
Feline Calicivirus Treatment
There is no cure for FCV, but there are ways to treat the symptoms and secondary infections while the illness runs its course. Treatments for relatively mild cases of cat flu caused by Feline Calicivirus may include:
- Cleaning discharge from eyes and nasal passages regularly
- Running a vaporizer to ease congestion
- Administering a veterinarian-prescribed nasal decongestant
- Maintaining a warm room temperature
- Providing a stress-free environment
- Giving medications to treat oral ulcers, eye lesions, and secondary infections
- Feeding soft, highly palatable, warmed food
- Supportive feeding (with a syringe) if the cat loses his appetite because he can’t smell his food due to nasal congestion
The majority of adult cats that are infected with FCV develop a relatively mild version of cat flu and recover easily, but the illness can be quite serious or even fatal in kittens and adult cats that don’t have strong immune systems. Treatments for more severe cases of FCV may include:
- Intravenous fluid replenishment
- Supplemental oxygen therapy
- Feeding via stomach tube
If a cat develops a severe case of limping syndrome due to arthritis or myalgia (a side effect that sometimes occurs with FCV), anti-inflammatories may be prescribed by a veterinarian as well. Most cats recover from limping syndrome.
How to Prevent FCV Infection
There is a vaccination for FCV (see Cat Vaccinations for a full list of vaccines that all cats should get). However, while it significantly reduces the risk of infection, it doesn’t provide 100% protection. A cat that has been vaccinated may still catch a wild strain of FCV and although he won’t become ill or will develop only a very mild illness, he can carry the virus and infect other cats.
Feline Viral Rhinotrachetis (FVR), also known as Feline Herpesvirus (FHV), is another common cause of cat flu, and there is a vaccine for this illness as well.
You can reduce the risk of FCV and FVR infection significantly by keeping your cats indoors (see Can Indoor Cats Be Happy? for ways to create a cat-friendly indoor environment).
This article is provided for informational purposes only and is not intended as a substitute for veterinary consultation and care.
- Mar Vista Animal Medical Center. (2009). “Feline Upper Respiratory Infection.” MarVistavet.com.
- Feline Advisory Bureau. (n.d.). “Limping Syndrome and Feline Calicivirus.” FABCats.org.
- McLeod, L., DVM. (n.d.). “Feline Calicivirus.” About.com.
- Nash, H., DVM, MS. (2011). “Sneezing and Feline Upper Respiratory Disease.” PetEducation.com.
- PetsMD. (n.d.). “Feline Calicivirus.” PetsMD.com.
- Radford et al. (2009). “Feline Calicivirus Infectino. ABCD Guidelines on Prevention and Management.” Journal of Feline Medical Surgery, 11(7): 556-564.
- Schelling, C., DVM. (2011). “Cat Vaccines.” CatVaccines.com.
- Stonewall Veterinary Clinic. (2011). “Feline Vaccination.”
- The Merck Veterinary Manual. (2008). “Feline Respiratory Disease Complex.” MerckVetManual.com.
- VetInfo.com. (2010). “Feline Calicivirus Symptoms.”