Companion Animals

Cat Feline Calicivirus: Severe Systemic Disease and Prevention

Virulent systemic calicivirus strains cause high-mortality outbreaks in cats that differ significantly from common mild FCV.

Key Facts

Common FCV causes mild upper respiratory signs but virulent systemic FCV (VS-FCV) causes vasculitis and 50%+ mortality
VS-FCV outbreaks occur in shelter and show cat populations with high density and multiple immune statuses
Current vaccines provide partial protection against FCV but do not fully protect against VS-FCV
Strict isolation and biosecurity prevent VS-FCV spread between cats in affected facilities

Welfare Considerations

VS-FCV causes multi-organ failure, severe skin ulceration, and rapid death even in vaccinated cats. Outbreak biosecurity preventing spread is the primary welfare intervention. Strict isolation of affected cats reduces transmission and limits total outbreak suffering.

What You Can Do

Isolate any cat with severe systemic signs alongside respiratory disease immediately
Vaccinate all cats regularly - incomplete protection is better than no protection
Report VS-FCV outbreak suspicions to your vet and local veterinary school for investigation