Equine influenza is a highly contagious respiratory disease that causes significant suffering in unvaccinated horses, but is effectively prevented by regular vaccination as part of routine equine health programs.
Equine influenza causes miserable illness: the combination of high fever (up to 41C), severe respiratory effort from coughing, and profound weakness keeps affected horses unable to move comfortably for days to weeks. Unlike many equine respiratory conditions, influenza progresses rapidly and the volume and duration of viral shedding makes epidemic spread through unvaccinated populations rapid. Major outbreaks have swept through countries with low vaccination rates, affecting thousands of horses simultaneously. The welfare cost of preventable influenza suffering - fever, respiratory distress, weakness, and extended convalescence - is significant and entirely avoidable through vaccination programs. Horse owners who vaccinate are also protecting their neighbors' horses through herd immunity effects, creating a community benefit from individual action. Competition requirements for vaccination have significantly improved population coverage in elite sport horse populations but recreational horses remain under-vaccinated.