Equine influenza outbreaks cause significant welfare harm across affected populations and demonstrate the importance of vaccination in preventing this highly contagious respiratory disease.
EI outbreaks cause acute welfare harm to individual horses through high fever, painful coughing, and profound debilitation. The highly contagious nature of EI means that single introduction events can affect large numbers of horses simultaneously, multiplying the welfare impact. Horses that return to work prematurely following EI infection face increased risk of secondary pneumonia that causes additional acute suffering. The preventable nature of EI through vaccination makes each outbreak case a welfare failure attributable to inadequate immunisation. Population-level vaccination coverage above a threshold level would prevent the explosive spread seen in major outbreaks.