Key Takeaways
Feline calicivirus spreads easily among infected cats, especially in crowded environments.
FCV is self-limiting and has no definite cure.
Vaccination is the most effective method for prevention.
Summary
Feline calicivirus, or FCV, is a highly contagious virus that causes upper respiratory tract infection and oral disease. It's known for being genetically diverse, able to mutate over time and create different strains. This is one of the many reasons why FCV can cause mild signs to severe disease.
Inside the body, the virus attaches to the cat's cells and uses their machinery to replicate. The new virus copies spread to nearby tissues and continue the cycle of infection. Some healthy cats can remain carriers that shed virus after treatment.
Clinical Signs
Common signs experienced by sick cats include:
Sneezing and nasal congestion. Frequent sneezing is one of the first symptoms. Swelling and mucus buildup can make breathing noisy and difficult
Eye and nasal discharge. The discharge may start clear but can turn thick, yellow, or green as secondary bacterial infections develop.
Conjunctivitis. FCV can target the epithelial cells of the conjunctiva, causing pink eye in cats. This may manifest as watery eyes and redness around the eye.
Oral ulcers. These raw sores can cause mouth pain and often appear on the tongue, gums, roof of the mouth, and lips. Cats may drool excessively due to pain.
Joint pain and stiffness. Some strains of feline calicivirus can also cause joint inflammation, resulting in limping or difficulty moving.
Loss of appetite. One of the cat's symptoms can be a decreased appetite, especially due to the pain from mouth ulcers.
Fever and lethargy. Most cats with the infection develop a fever because of the immune system's efforts to defend the body. They may also feel tired.
Severe Symptoms: Virulent Systemic Feline Calicivirus
In rare cases, highly aggressive strains can result in FCV-associated virulent systemic disease. Up to 60% of cats with FCV-VSD may die from the disease, with many experiencing more severe symptoms such as:
High fever
Swelling on the head, face, and legs
Crusting sores and hair loss on the nose, ears, and footpads
Jaundice
Bleeding under the skin and GI tract
Organ damage
Death
FCV Transmission
Infected cats, contaminated objects, and human transmission.
Feline calicivirus is transmitted primarily through direct contact with infected cats. The virus is shed heavily through infectious secretions such as saliva, eye discharge, and nasal mucus. This means that cats who groom, play, or fight with carrier cats can acquire the viral infection.
Other cats may also contract FCV by interacting with objects and surfaces contaminated with respiratory droplets. FCV is highly resilient, capable of surviving for 1-4 weeks on litter boxes, food/water bowls, or bedding.
Feline calcivirus can also be transmitted when a person handles an infected cat and then touches another healthy cat without washing their hands or changing contaminated objects and clothing.
The virus spreads more easily in places where multiple cats live close together. This includes unhygienic animal shelters, catteries, and multi-cat environments.
In Dubai, boarding facilities, daycares, grooming salons, and catteries require pet owners to present proof of their cats’ updated vaccination records. These measures are taken to ensure the safety of all cats in the facility and prevent the spread of disease.
Cats at Risk
Cats most at risk of feline calicivirus include young kittens, unvaccinated cats, older cats, cats with weak immune systems, and outdoor cats. Kittens are vulnerable to severe signs because their immune systems are still developing, while unvaccinated cats have less protection against FCV.
Senior and immunocompromised cats have a harder time fighting off this upper respiratory disease due to weakened immune responses. Additionally, cats that frequently stay outdoors are at higher risk of encountering infected stray cats and contaminated environments.
How Is Calicivirus Diagnosed in Cats?
A physical exam, RT-PCR, and viral isolation.
We focus on your cat's clinical signs first to get an initial idea of their condition.
The most effective way to diagnose FCV is through RT-PCR. It's similar to how a PCR test works, but before replicating DNA, the RT-PCR test takes an extra step to convert RNA into DNA. This is because FCV is an RNA virus.
RT-PCR is highly accurate at detecting the virus, even in asymptomatic carriers.
Viral isolation is another method we can use to diagnose feline calicivirus. It works by collecting a sample from the cat's nose, mouth, or eyes. The sample will be introduced to a culture of living cells.
If the cat is actively shedding the virus, it will infect and destroy the cells in the culture. It's then confirmed through specialized staining.
We also do blood tests to rule out other underlying diseases.
Treatment
Unfortunately, there is no definite cure or antiviral medication for feline calicivirus. Treatment will focus on supportive medication and care to provide comfort and relief while their immune system fights the virus
Our vets may prescribe antibiotics to treat and manage secondary infections that can develop as a result of the calicivirus infection. Cats with pain from oral ulcers may be given non-steroidal anti-inflammatory drugs to relieve pain.
Keeping cats hydrated is important, especially if nasal congestion or oral ulcers have reduced their water intake. In severe cases, intravenous fluids may be necessary.
Cats with oral ulcers may refuse to eat. You can help by offering soft and palatable foods. Warming the food can also make it more enticing. If they have not eaten for three days, bring them to the clinic. Severely affected cats may need hospitalization.
Most cats recover well within 7–10 days, although cases involving more virulent strains may take longer.
Preventing a FCV Infection
Routine vaccination is the most effective method of preventing a feline calicivirus infection. Vaccines help prepare your cat's immune system to recognize and fight off the virus. We recommend starting your cat's first series at 6-8 weeks of age.
This will be followed by two additional boosters spaced 3-4 weeks apart. Adult cats will need annual boosters. While vaccinated cats can still become infected with FCV, the severity of respiratory signs will be significantly reduced.
Since the virus can also survive on surfaces and items, it's best to sanitize them weekly. Use a bleach solution for bowls, carriers, and hard surfaces. We also recommend keeping your cat indoors, away from potentially infected stray cats.
If you have multiple cats or a new cat, be sure to isolate them in a designated room if you notice signs of a respiratory infection.
“Feline calicivirus is one of the many respiratory diseases that can be prevented with the help of routine vaccination. Keeping these up to date is crucial."
- Dr. Lidija Krvavac
Frequently Asked Questions
Does FCV go away on its own?
Mild cases may resolve on their own as the cat's immune system naturally fights off the infection. However, it's best to seek treatment. Supportive care provides relief and prevents secondary infections.
Is this contagious to humans or dogs?
No, feline calicivirus cannot affect humans or dogs because it is a strictly species-specific virus that affects only cats.
What is the incubation period of feline calicivirus?
The incubation period ranges from 2-10 days, with most cats developing visible symptoms within 2-6 days of exposure.
How common is it in cats?
FCV is very common globally. It affects around 10% of cats in small household settings and up to 90% in crowded environments.
What should I do if I think my cat has FCV?
Isolate them from other cats in the house. Contact our vets and explain all the symptoms you observe. For home care, we recommend wiping any eye or nose discharge with a warm cloth. You can also let your cat sit in a steamy bathroom for about 10 minutes to clear nasal congestion.
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