Feline calicivirus is a virus which causes flu-like symptoms in cats. It is usually not too serious. It’s spread through direct contact with saliva, eye, or nose discharge, or sometimes the feces of infected cats. Calicivirus is part of the feline upper respiratory infection complex. This is a group of viral and bacterial infections, also including chlamydia and herpesvirus, which cause sneezing and discharge from the eyes and nose. Cats often have two or more of these upper respiratory infections at the same time.
What are the signs of calicivirus?
There are many different strains of calicivirus, and the clinical effects of infection vary from strain to strain. Some strains make cats very ill, while others cause only mild illness.
Symptoms may include any of the following:
- Lack of appetite
- Sores in the mouth, on the lips or tongue, or on the tip of the nose (or even on the feet)
- Inflammation around the mouth (stomatitis)
- Drooling
- Runny eyes and nose
- Sneezing
- Difficulty breathing (with or without pneumonia)
- Stiff, sore joints or muscles (may resemble arthritis)
- Fever
Some cats may also carry the virus for years without having any symptoms at all.
The severity of the signs is determined by many factors, including age (kittens are typically more affected than adults), the particular virus strain, how much virus a cat has come in contact with, and the presence of concurrent disease.
Once a cat has been infected with calicivirus, even after recovery, it continues to spread virus and be contagious to other cats. This may continue for a few weeks to as long as a few years after apparent recovery. These cats are known as “carrier” cats.
How does a cat become infected with calicivirus?
Infected cats shed virus from their eyes, mouth, and nose. Virus is spread either by direct contact with a sick or carrier cat or by indirect contact with infected surfaces. Calicivirus can survive in the environment on infected surfaces for 8 to 10 days, making indirect contact as important as direct contact as a source of infection.
The diagnosis of calicivirus infection is usually made based on clinical signs (oral ulcers, eye and nose discharge, etc). There are also laboratory tests available to specifically test for calicivirus, helping to distinguish it from other causes of upper respiratory infections. This may be useful in chronic or more severe cases.
How is calicivirus infection treated?
In most cases, supportive care is all that is required for treatment of calicivirus infection. This may include frequent cleaning of eyes and nose and/or nasal humidifiers or nasal drops. More severe cases may require treatment for dehydration, oral ulceration, or fever. Patients with difficulty eating (due to oral ulcers or nasal congestion) may require special food or medications to entice them to eat. Veterinarians may also prescribe antibiotics as well to treat secondary bacterial infections that often accompany calicivirus infection. As with most viral infections, there is no specific medication to cure calicivirus.
There is a very strong version of feline calicivirus called VS-FCV infection. If your cat has this form of the virus then more aggressive treatment is needed. This will likely include fluid therapy to avoid dehydration and antibiotics to avoid infection.
How can I prevent my cat from becoming infected?
The best method of protecting your cat against calicivirus is proper vaccination. All kittens receive a series of vaccinations 3-4 weeks apart (starting at 6-8 weeks of age). These vaccination boosters are typically administered as part of an HCP (herpesvirus, calicivirus, and panleukopenia) combination vaccine. After the initial series of vaccinations, your veterinarian will discuss with you an appropriate schedule of revaccination.