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Feline calicivirus (new strains)


Synonym(s): Virulent systemic disease, VSD strains




  • Family: Caliciviridae.
  • Genus: Vesivirus.

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Clinical Effects



  • Epithelium of respiratory tract, oral cavity, conjunctiva; virulent systemic strains may have tropism for other cells including vascular endothelium and hepatic cells.


  • Many clinically recovered cats become carriers of feline calicivirus.
  • Carriers shed virus more or less continuously from the oropharynx.
  • The number of cats in the population who are carriers is reasonably high and prevalence depends on the husbandry conditions of the cat; multi-cat colonies can have a prevalence of FCV of up to 90% (see feline calicivirus Feline calicivirus).


  • Fomites very important in spread of the virus; shed in respiratory secretions.

Pathological effects

  • Virulent systemic strains are associated with subcutaneous edema, hemorrhages; epithelial necrosis, including crusting of pinna, face; fluid in abdominal and thoracic cavities (~100 ml); necrotizing hepatitis; pancreatitis; interstitial pneumonia; lesions may be found in intestinal crypts.
  • More severe disease reported in adults vs. kittens for the virulent systemic strains, similar to rabbit hemorrhagic disease, caused by a calicivirus of rabbits.

Other Host Effects

  • Typical signs include fever, facial or limb edema or sores, alopecia and ulceration of face or feet and jaundice.


Control via animal

  • Strict isolation of affected animals; isolate shelter/rescue cats for 1-2 weeks before introducing to other cats.
  • Affected cats should be barrier nursed; staff nursing these cats should preferably have no cats at home to prevent infection of their own animals.
  • All cats from affected households should be kept indoors to prevent spread of the virus.

Control via chemotherapies

  • Interferon Interferon has been used to treat some cats with virulent systemic disease although there are no published reports of the efficacy of this treatment and it is not licensed for this use. Anecdotal reports suggest there has been some improvement seen in a few affected cats following treatment.
  • Anecdotal information indicates corticosteroids may be helpful in acute disease.

Control via environment

  • Most common in multicat environments; outbreaks reported in veterinary clinics; strict isolation of any suspected infected cats paramount.
  • Fomites, including clinic personnel/owners/etc are very important in spread; good disinfection and hygiene important to minimize spread.


  • Due to strain variation, coverage of protection with vaccines containing single strains may be incomplete.
  • Experimentally some vaccines have been found to give some protection against the virulent systemic strains although in field cases many of the affected cats have been vaccinated.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Coyne K P, Dawson S, Radford A D et al (2006) Long-term analysis of feline calicivirus prevalence and viral shedding patterns in naturally infected colonies of domestic cats. Vet Microbiol 118 (1-2), 12-25 PubMed.
  • Coyne K P, Jones B R, Kipar A et al (2006) Lethal outbreak of disease associated with feline calicivirus infection in cats. Vet Rec 158 (16), 544-550 PubMed.
  • Foley J, Hurley K, Pesavento P A et al (2006) Virulent systemic feline calicivirus infection: local cytokine modulation and contribution of viral mutants. J Feline Med Surg 8 (1), 55-61 PubMed.
  • Hurley K E, Pesavento P A, Pedersen N C et al (2004) An outbreak of virulent systemic feline calicivirus disease. JAVMA 224 (2), 241-249 PubMed.
  • Pedersen N C, Elliot J B, Glasgow A et al (2000) An isolated epizootic of hemorrhagic-like fever in cats caused by a novel and highly virulent strain of feline calicivirus. Vet Microbiol 73 (4), 281-300 PubMed.
  • Radford A D, Dawson S, Wharmby C et al (2000) Comparison of serological and sequence-based methods for typing feline calicivirus isolates from vaccine failures. Vet Rec 146 (5), 117-123 PubMed.
  • Kreutz L C, Johnson R P & Seal B S (1998) Phenotypic and genotypic variation of feline calicivirus during persistent infection of cats. Vet Microbiol 59 (2-3), 229-236 PubMed.
  • Baulch-Brown C, Love D N & Meanger J (1997) Feline calicivirus: a need for vaccine modification? Aust Vet J 75 (3), 209-213 PubMed.
  • TerWee J, Lauritzen A Y, Sabara M et al (1997) Comparison of the primary signs induced by experimental exposure to either a pneumotrophic or a 'limping' strain of feline calicivirus. Vet Microbiol 56 (1-2), 33-45 PubMed.
  • Turnquist S E & Ostlund E (1997) Calicivirus outbreak with high mortality in a Missouri feline colony. J Vet Diag Invest (2), 195-198 PubMed.

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