Feline Calicivirus (FCV): Symptoms & Treatment
- Feline calicivirus (FCV) is a very contagious viral infection that commonly causes sneezing, nasal and eye discharge, fever, and painful mouth ulcers in cats.
- Many cats improve with supportive care, but illness often lasts about 1-3 weeks rather than only a few days, and kittens can get sick faster than adults.
- Mouth ulcers, drooling, and reluctance to eat are especially important signs because oral pain can lead to dehydration and poor calorie intake.
- Treatment focuses on supportive care such as fluids, pain control, nutrition support, and monitoring for secondary bacterial infection or pneumonia.
- The FVRCP vaccine is a core vaccine that helps reduce the severity of disease, but vaccinated cats can still become infected and shed virus.
What Is Feline Calicivirus (FCV)?
Feline calicivirus is a common upper respiratory virus in cats. It spreads easily between cats through saliva, nasal secretions, eye discharge, shared bowls, bedding, litter-area contamination, and droplets from sneezing. It is one of the major infections included in the feline respiratory disease complex, along with feline herpesvirus.
Many cats develop a mild to moderate illness with sneezing, congestion, eye discharge, fever, and painful ulcers in the mouth. Those mouth sores are especially helpful clues because they are more typical of FCV than some other cat respiratory infections. Even when the infection is not severe, cats may stop eating because their mouth hurts or they cannot smell food well.
Most cats recover with supportive care, but recovery often takes about 14-21 days. Some cats continue to shed virus after they seem better, and a portion become longer-term carriers. Rare strains can cause virulent systemic calicivirus, a much more serious form linked to facial or limb swelling, skin sores, jaundice, breathing trouble, and a higher death rate.
FCV is species-specific, so it is not considered a human health risk. Still, it can move quickly through shelters, catteries, foster settings, and multi-cat homes, so early isolation and cleaning matter.
Symptoms of Feline Calicivirus
- Sneezing and nasal congestion, often mild at first but sometimes progressing to thick discharge
- Discharge from the nose and eyes, with squinting or red eyes in some cats
- Ulcers on the tongue, gums, palate, lips, or nose that can make eating painful
- Drooling or pawing at the mouth because of oral pain
- Decreased appetite or refusal to eat, especially when congestion and mouth ulcers happen together
- Fever, hiding, and low energy
- Limping or joint pain in some strains, especially in kittens
- Coughing, open-mouth breathing, or fast breathing if lower airway disease or pneumonia develops
Mouth ulcers are one of the most useful clues that FCV may be involved, but not every cat gets them. Some cats mainly show cold-like signs, while others have fever and a temporary limping syndrome that can come on suddenly and improve within a few days.
See your vet promptly if your cat is not eating, seems dehydrated, is breathing harder than normal, or is a young kitten, senior cat, or immunocompromised cat. See your vet immediately for open-mouth breathing, collapse, severe swelling, skin sores, yellow gums or eyes, or profound lethargy, because those signs can fit a severe or systemic form of disease.
How Do Cats Get Calicivirus?
FCV spreads through direct cat-to-cat contact and through contaminated items in the environment. Shared food bowls, water bowls, bedding, litter tools, carriers, and human hands can all help move the virus from one cat to another. Sneezing can also spread infectious droplets several feet.
Cats are often contagious before obvious signs appear and usually remain contagious for at least several weeks after symptoms start. In some cats, viral shedding continues much longer. That is one reason outbreaks can be hard to control in shelters and multi-cat homes.
The virus can survive in the environment for about a week and sometimes longer in cool, damp conditions. Good hygiene matters. Diluted bleach can be effective on cleaned surfaces, but your vet or shelter team may recommend other disinfectants depending on the setting.
Kittens, unvaccinated cats, stressed cats, and cats living in crowded housing are at highest risk. Vaccination lowers disease severity, but it does not fully prevent infection because FCV has many strains and can vary over time.
How Is Calicivirus Diagnosed?
Your vet may suspect FCV based on the pattern of signs, especially when upper respiratory symptoms happen along with mouth ulcers or limping. In many routine cases, treatment decisions are based on the cat's exam findings, hydration status, appetite, and breathing rather than on a specific virus name.
Testing can be helpful in some situations. Your vet may recommend PCR testing on oral, nasal, or eye swabs during outbreaks, in shelter medicine, in severe disease, or when the diagnosis is unclear. PCR can detect FCV genetic material, but results still need to be interpreted with the cat's symptoms because some cats may shed virus without being the sole cause of illness.
For cats that are very sick, your vet may also suggest blood work, chest X-rays, or other supportive testing. These tests help look for dehydration, inflammation, pneumonia, organ involvement, or complications that change the treatment plan.
A practical point for pet parents: a test result may confirm FCV, but it usually does not replace supportive care. The most important questions are whether your cat is breathing comfortably, staying hydrated, and getting enough calories while healing.
Treatment Options for Feline Calicivirus
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Conservative Care
- Office exam and hydration check
- Supportive home-care plan from your vet
- Pain relief for oral ulcers when appropriate
- Eye or nose cleaning guidance
- Palatable canned food, warming food, and smell-enhancement strategies
- Monitoring for dehydration, worsening congestion, or poor intake
Standard Care
- Exam plus targeted diagnostics as needed
- Subcutaneous fluids or day-hospital supportive care
- Prescription pain control for mouth ulcers
- Antinausea medication or appetite support when indicated
- Antibiotics only when your vet suspects secondary bacterial infection, pneumonia, or significant nasal discharge
- Recheck visit to assess hydration, breathing, and food intake
Advanced Care
- Hospitalization and isolation nursing
- IV fluids and electrolyte support
- Feeding tube placement or assisted nutrition when a cat will not eat
- Chest imaging and oxygen support if pneumonia or severe airway disease is present
- Expanded blood work and monitoring for systemic involvement
- Critical care for suspected virulent systemic FCV, severe oral pain, or profound dehydration
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Calicivirus
Bring these questions to your vet appointment to get the most out of your visit.
- Do my cat's signs fit uncomplicated FCV, or are you worried about pneumonia or a more severe systemic form? This helps you understand how serious the illness appears today and what changes would mean the plan needs to escalate.
- Is my cat hydrated enough to stay home, or would fluids in the clinic help? Dehydration is common when cats are congested or have painful mouth ulcers, and it can slow recovery.
- What is the best way to keep my cat eating while the mouth ulcers heal? Cats can decline quickly when they stop eating, so practical feeding strategies matter.
- Would you recommend testing, or is treatment based mainly on symptoms in my cat's case? PCR testing can be useful in some situations, but not every cat needs it.
- Are there signs of secondary bacterial infection that make antibiotics reasonable here? Antibiotics are not for the virus itself, so it is helpful to know why they are or are not being used.
- How long should I isolate my cat from other cats in the home? FCV is highly contagious, and cats can shed virus for weeks after signs begin.
- What warning signs mean I should call back the same day or go in immediately? Clear return precautions help you act fast if breathing, hydration, or appetite worsens.
- When should my other cats be examined or boosted for vaccines? Household risk assessment can reduce spread and may lower disease severity in exposed cats.
How to Prevent Feline Calicivirus
The most important prevention step is vaccination. FCV protection is included in the FVRCP core vaccine. Current feline vaccination guidance supports starting the kitten series around 6-8 weeks of age, repeating every 3-4 weeks until 16-20 weeks, then giving a booster at about 6 months to 1 year depending on the protocol your vet uses, followed by boosters at intervals based on lifestyle and vaccine type.
Vaccination does not guarantee that a cat will never get infected. What it usually does is lower the chance of severe disease and shorten illness. That is still very valuable, especially for kittens and cats that may be exposed to other cats through boarding, fostering, rescue work, or multi-cat housing.
If one cat in the home is sick, separate food bowls, litter supplies, bedding, and resting areas can help reduce spread. Wash hands after handling the sick cat, and clean surfaces regularly. Ask your vet which disinfectant is best for your home setup, because contact time and surface cleaning matter.
When bringing home a new cat, a quarantine period of at least 1-2 weeks is a practical minimum. During that time, watch for sneezing, eye discharge, oral pain, or poor appetite, and make sure vaccines and any needed intake exam are up to date before full introduction.