Equine influenza is a highly contagious respiratory disease that causes significant welfare suffering in unvaccinated horses, and vaccination is a fundamental welfare preventive measure for all horses in contact with others.
Equine influenza causes severe acute welfare suffering — fevers reaching 41 degrees Celsius, exhausting cough, and profound lethargy leave horses unable to eat or move comfortably for days. Working horses through early-stage infection dramatically worsens outcomes and prolongs suffering. Vaccination significantly reduces both infection risk and disease severity in horses that do become infected. The welfare case for vaccination is straightforward — preventing or reducing the severity of a debilitating respiratory illness. Ensuring vaccination coverage across yards and equestrian facilities provides herd immunity that protects horses that cannot be vaccinated for medical reasons. The 2019 outbreak demonstrated that surveillance and rapid response protocols are essential alongside vaccination for outbreak control.