Recurrent airway obstruction (RAO, equine asthma) is one of the most common chronic respiratory conditions in horses. Reducing allergen exposure and appropriate medical management can dramatically improve quality of life for affected horses.
RAO causes chronic respiratory discomfort that, in untreated or inadequately managed horses, is a persistent background welfare compromise. A horse that coughs repeatedly during exercise, produces excess nasal discharge, and is exercise intolerant is experiencing ongoing respiratory discomfort with every breath during affected periods. Severe RAO — where horses display respiratory distress at rest, visible laboured breathing, and obvious distress — represents acute welfare harm. The central insight in RAO management is that environmental management (removing allergens from hay and bedding) is both more effective and more welfare-appropriate than medication alone. Horses managed on maximum turnout with soaked hay or haylage and dust-free bedding frequently show dramatic improvement without requiring ongoing medication — an outcome better for the horse and less dependent on owner compliance with drug administration schedules. Horses stabled in dusty hay barns with deep straw bedding during their working lives experience a preventable accumulation of respiratory compromise that shortens their comfortable working life.