Equine asthma (formerly heaves or RAO) is the most common chronic respiratory disease in horses, causing significant welfare harm that is largely preventable through management.
Equine asthma causes respiratory distress that ranges from reduced exercise tolerance to severe breathing difficulty at rest. The condition is largely management-related — dusty hay, enclosed stabling, and wood shaving bedding are primary triggers. Transitioning affected horses to humidified or low-dust forage, rubber matting over minimal bedding, and maximum outdoor turnout can achieve clinical remission without medication in many cases. Bronchodilator and corticosteroid treatment is available for severe acute exacerbations.