Equine Recurrent Airway Obstruction (RAO), also known as heaves or broken wind, is one of the most common ailments of middle-aged horses. Inflammation of the airways is induced by organic dust exposure. This illness is characterized by neutrophilic inflammation, bronchospasm, excessive mucus production and pathologic changes in the bronchiolar walls. Clinical signs resolve themselves within 3-4 weeks after the animals undergo environmental change. Horses suffering from RAO are susceptible to allergens throughout their lives, and should therefore be properly managed. The most important aspect of therapy is to eliminate dust exposure, the administration of corticosteroids and the of use bronchodilators to improve pulmonary function.