Felis ISSN 2398-2950

Feline calicivirus disease

Synonym(s): FCV

Contributor(s): Leah Cohn, Susan Dawson, Alan Radford


  • One of the causes of feline upper respiratory tract disease (cat flu). There are a large number of different strains of feline calicivirus with varying antigenicity and pathogenicity Feline calicivirus    Feline calicivirus (new strains).
  • VSD (virulent systemic disease); has been shown to a highly infectious disease.
    In some reported outbreaks spread of infection has been based around a veterinary clinic, therefore, barrier nursing of any confirmed or suspect cases is required. 
  • Rarely, a cause of acute severe hemorrhagic-like fever.


Predisposing factors


  • Following oronasal infection the virus multiplies in the tissues of the oropharynx and the respiratory tract. Oral ulcers which are a frequent feature of the disease begin as thin-walled vesicles which quickly ulcerate. Less commonly the lower respiratory tract has signs of pathology with the development of areas of acute exudative pneumonia.
  • In some cats the joints are a site of viral infection causing an acute synovitis with thickening of the synovial membrane and increased quantities of synovial fluid.
  • The pathogenesis of the more recently reported hemorrhagic/hepatic syndrome includes vasculitis, coagulopathy and necrosis of skin with clinical lesions of edema, skin necrosis and coagulative necrosis of hepatic tissues and pathology in the pancreas.


  • Replication of virus occurs mainly in the mucosa of the respiratory tract although other tissues may be affected depending on the strain of virus.
  • In cases of VSD virus has been identified in hepatic cells in association with areas of liver pathology.


  • The majority of cats with upper respiratory disease recover from clinical disease within 2 weeks of infection.


  • Clinically recovered cats frequently become carriers of the virus and act as a source of infection to other susceptible animals. Vaccination does not eliminate nor prevent development of the carrier state. The majority of cats will still be shedding virus 30 days after infection although some cats are then able to eliminate the virus, and there is an exponential fall off in the number of cats remaining carriers. A few cats will remain carriers longterm for months or years. Re-infection is possible and is likely to be common in groups of cats.
  • For VSD the index case in some outbreaks has been related to respiratory disease in a rescue shelter.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Coyne K P, Jones B R, Kipar A et al (2005) Lethal outbreak of disease associated with feline calicivirus infection in cats. Vet Rec 158 (16), 544-550 PubMed.
  • Hurley K F & Sykes J E (2003) Update on feline calicivirus: new trends. Vet Clin North Am Small Anim Pract 33 (4), 759-772 PubMed.
  • Schorr-Evans E M, Poland A, Johnson W E et al (2003) An epizootic of highly virulent feline calicivirus disease in a hospital setting in New England. J Feline Med Surg (4), 217-226 PubMed.

Other sources of information

  • Gaskell R M, Radford A D & Dawson S Feline Respiratory Disease. In: Infectious diseases of the Dog and Cat. Ed: C E Greene, In press.


  • Small Animal Virology Group, University of Liverpool, Leahurst, Neston, South Wirral CH64 7TE, UK.
  • For the full ABCD Guidelines on Feline Calicivirus Disease, visit  www.abcd-vets.org .