Virulent systemic feline calicivirus is a severe and often fatal variant causing systemic vasculitis, ulceration, and organ failure, representing a significant welfare emergency in affected cats.
Virulent systemic calicivirus causes profound suffering through rapid systemic deterioration, severe ulceration of skin and mucous membranes, respiratory distress, and organ failure. Affected cats deteriorate quickly and intensive supportive care is required. The high mortality rate and severity of disease mean welfare-focused decisions about humane euthanasia are often necessary. Outbreaks in multi-cat facilities represent welfare emergencies requiring immediate isolation, intensive nursing, and potential facility closure. The welfare burden extends to shelter staff and owners witnessing severe illness.