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Identifying Feline Calici Viral Disease and Their Symptoms in House Cats

This is an important respiratory disease caused by feline Calicivirus, which primarily affects domestic cats. The disease is characterized by bi-phasic fever, occulonasal discharges and respiratory distress accompanied by vesiculation leading to ulceration in mouth and nostrils.

Incidence of Feline Calici Virus Infection

Kittens are more susceptible to the disease. The disease is known to be prevalent through out the world.

Causes of Calici Viral Infection

The disease is caused by feline calicivirus (RNA virus), which is lightly bigger than the picorna virus, and its virion has 32 cup-shaped depressions on the surface. The virus is stable and resistant to heat, acids and bile.

A high degree of antigenic heterogeneity of the virus strains exists and as such some strains cause acute and/or chronic clinical or subclinicall upper respiratory infection while some others cause pneumonia in young animals.


The virus is present in high concentrations in mouth particularly the tonsils where it actively replicates and can be recovered even weeks after infection. The recovered animals act as carriers and exhibit serum antibody titres. Other modes of infection include oral route, and aerosol infection.


Clinical signs of Feline Calici Virus Infection in Cats

Despite high morbidity rate, the mortality rarely exceeds 30 per cent. It is self-limiting infection. The disease is actually super imposed with feline rhinotracheitis or Chlamydia psittacii infection. In the later infection, persistent conjunctivitis is a usual complication.

The important clinical signs in uncomplicated feline Calicivirus infection includes-

  • Biphasic fever
  • Lethargy
  • Stiff gait
  • Depression
  • Pulmonary rales
  • Enteritis
  • Arthritis
    The clinical course may vary from acute to chronic stage. The virus can be isolated from high percentage of cats affected with chronic stomatitis.

Diagnosis of Feline Calici Viral Disease in Cats

  • By clinical symptoms- characteristic vesicles and ulcers in mouth and nostrils
  • Demonstration of inclusion bodies in oral mucosa
  • PCR for viral genome sequences


  • Vaccination to prevent the development of the disease
  • Non-steroidal anti-inflammatory drugs to prevent arthritis
  • Oral antibiotics to control and treat the secondary bacterial infections
  • Antibiotic eye ointments to prevent secondary bacterial infections in the eye

Prevention and Control

The regimen of Fel-O-vax or FHV 1 is followed for prevention of Feline Calici virus disease. The vaccine reduces the incidence of the disease but does not prevent infection.

Kittens of 8 to 10 weeks of age need to be vaccinated against this disease and followed by booster dose after 3 to 4 weeks. This should be vaccinated for the cats annually. Try to use 1:32 dilution of any household bleach to prevent the intrusion of this virus. Always keep your cat indoors and also away from other cats.

Related Resources

Feline calicivirus- Wikipedia

Feline Upper Respiratory Viruses - Part Two: Calici Virus