Equine influenza is a highly contagious respiratory disease that causes significant suffering and can spread rapidly through equine populations at events and training facilities. Vaccination and biosecurity are foundational welfare and public health interventions.
Equine influenza causes genuine suffering — the high fever, persistent cough, and systemic illness of clinical equine flu is genuinely distressing for affected horses, and the weeks of rest required for full recovery impose both welfare costs from inactivity and economic costs to owners. The rapid spread through equine populations at competitions and markets means that a single affected horse can expose hundreds of others within hours. The welfare case for vaccination is therefore both individual — protecting each horse from a miserable illness — and population-level, preventing the widespread outbreaks that affect entire competition seasons. Returning horses to work before full recovery is a common management error that causes chronic respiratory complications and extended welfare costs. Adequate rest following equine influenza infection is as important as the initial treatment.