Horse Respiratory Infections: Equine Influenza, Herpesvirus and Welfare Management

Respiratory infections cause significant welfare compromise in horses, restricting exercise capacity and causing systemic illness. Prevention, early recognition, and appropriate management protect horse welfare.

Key Facts

Equine influenza is a highly contagious respiratory disease causing fever, nasal discharge, cough, and exercise intolerance
Equine herpesvirus types 1 and 4 cause respiratory disease, abortion, and rarely neurological illness
Respiratory infections spread rapidly at equestrian events and shared facilities through horse-to-horse contact
Recovery from equine influenza requires 2 to 3 weeks rest for each day of fever to prevent complications
Vaccination significantly reduces the severity and duration of equine influenza in vaccinated horses
Horses returned to work too soon after respiratory infection risk developing secondary complications
Quarantine of new arrivals for 3 weeks prevents introduction of infectious agents into resident horse populations

Welfare Considerations

Equine respiratory infections cause significant acute welfare compromise through fever, systemic malaise, and respiratory discomfort, with secondary complications including bacterial pneumonia representing serious welfare emergencies. The welfare implications extend beyond the acute illness to the recovery period, where pressure to return horses to work prematurely risks severe complications. The welfare-appropriate guideline of 1 week rest per day of fever, while economically challenging for competitive horses, reflects the genuine physiological needs of a respiratory tract recovering from viral infection. Vaccination, while not providing complete protection, reduces disease severity and aids herd immunity development that protects horses that cannot be vaccinated. Biosecurity practices including new arrival quarantine are the most effective practical prevention measures at yard level.

What You Can Do

Vaccinate all horses against equine influenza on recommended schedules for their competitive exposure
Impose 3-week quarantine for all new arrivals before mixing with resident horses
Seek veterinary assessment for any horse with fever, nasal discharge, or persistent cough
Follow veterinary guidance on rest requirements following respiratory illness strictly
Stay informed about equine disease outbreaks in your region through surveillance networks