Feline Calicivirus (FCV) is a common virus. It causes upper respiratory infections and oral diseases in cats. The virus infects cats and cat population’s worldwide. It can also cause disease in both domestic and exotic cats. There are at least 40 different strains of FCV. As a result, this makes it a difficult to study, as the severity and how contagious are may vary.

Typical symptoms of feline calicivirus include:

  • sneezing
  • nasal congestion
  • conjunctivitis (inflammation of the membranes lining the eyelids),
  • discharge from the nose or eyes. The discharge can be clear or may contain pus.
  • lesions in the mouth and around teeth.

Feline Calicivirus

While pneumonia and mycoplasma have many of the same symptoms. Cats with feline calicivirus will often develop ulcers on the tongue, hard palate, gums, lips or nose. Ulcers in the mouth will cause the cat to salivate or drool excessively.

Depending entirely on which strain of the virus the cat has with, other symptoms can occur. Some strains cause the cat to develop lameness in one or more joints: this occurs more in kittens than in adult cats.

Prior infection with one strain may reduce illness and shedding upon exposure to an unrelated strain, (Povery & Ingersoll).

The strain referred to as VS-FCV (Virulent Systemic Feline Calicivirus) causes the initial symptoms of ulcers but then the cat develops a high fever, severe depression, edema of the legs and/or face, jaundice, and multiple organ faults. This strain is highly infections and mortality is 67%. (Yuill)

How does Feline Calicivirus spread?

Calicivirus is highly contagious. It spreads through the active viral particles in saliva and secretions from the nose or eyes. Airborne particles spray through the air via sneezing. It is the only speculation that the virus spreads through urine or feces, so it is not considered a major source of infection. The virus can survive up to 30 days in a dry, warm environment and even longer in cold temperatures. Bedding and litter boxes are a source of infection from the secretions of the infected cat.

Calici is most prevalent in multi-cat households, some-catteries, shelters, and feral cat communities. Overcrowded or unsanitary conditions, poorly-ventilated air-supply, inadequate diet, are all stressful and conducive to illness. This demonstrates the need for cleanliness in all cat and kittening areas.

Infection Time Span

Incubation, once exposed, can be 2 – 6 days and symptoms will last, typically, up to 3 weeks. Notable is that a cat can continue to be a carrier or silent shedder of the disease even after their symptoms have disappeared. Most cats shed post-infection for at least 30 days and a few for several years.

Recent studies have shown that in a population of FCV positive cats:
In 30 days, 50% of the population with be shedders,
60 days, 25% will be shedders,
90 days, 12% will be shedders,
In a year’s time, you will have a low population that will be the lifelong carriers of the virus,
Those cats over 3 years of age and have had their vaccinations have a high probability of getting rid of the virus entirely.

Diagnosis of FCV

The prevalence of upper respiratory diseases in cats means that a clinical diagnosis of feline calicivirus must have a PCR test. The veterinarian will take an eye, nose, or throat swab and use the clinical labs available such as UC Davis School of Veterinary Medicine, Zoologix or Idexx Real PCR testing.

Treatment for FCV

Except in cases of severe pneumonia, treatment is supportive and can be done at home. Most of all, eating and drinking are essential. Due to the ulcers that may form in the mouth, offer soft foods that smell good. Also, keep the cat’s eyes and nose clear by wiping with a soft cloth. In addition, ensure that they are warm and comfortable in a well-ventilated room. Placing them in a room with a hot shower or a humidifier will help to break up the mucus in the airways.

Antiviral medications have never been proven to affect or help cats with calicivirus. But as secondary infections can occur, some medication is recommended.

Antibiotic eye ointments for secondary infections.
Oral antibiotics to prevent or treat secondary bacterial infections.
Vaccination to prevent the progression of the disease.

Breeding with FCV

The question here should not be “How can I breed with Feline Calicivirus in my cattery?” but, “Should I breed with Calici in my cattery?”

A positive queen may have kittens but they will have a high mortality rate. To be successful, the breeding queen must receive a vaccination before mating. Remove kittens from the queen while the maternal antibodies are still strong, at most, 4 weeks old to stop the virus. And this is still no guarantee that they are not carrying the virus. As recent studies have shown, we are already over-vaccinating our pet population.

Breeding queens, on average, are bred every 6 months to a year. That type of overload of vaccinations on her immune system will compromise her basic, natural immunity and almost ensure that she will not be able to get rid of the virus on her own.


In conclusion, administer core vaccinations as kittens. Provide a good diet, exercise, fresh-air and clean-uncrowded conditions. This will help to ensure a cat has a healthy immune system. If exposure to the virus happens, they will shake it off like the common cold.



Yuill, Cheryl (2010) Infectious Diseases, Medications.
Povey C, Ingersoll (1975) Cross-protection among feline caliciviruses.

*Photo used under the Creative Commons Attribution-Share Alike 3.0 Unported license; author Kalumet (de:Benutzer:Kalumet)

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