Equine Recurrent Airway Obstruction (RAO): Welfare Guide

Key Facts

• RAO affects up to 14% of adult horses in temperate climates, with older horses most severely affected
• The primary triggers are hay dust, mold spores, and ammonia in poorly ventilated stabling
• Clinical signs include increased respiratory rate, nostril flare, abdominal heave line, and exercise intolerance
• Environmental management (dust-free forage, improved ventilation) is the cornerstone of treatment
• Bronchodilators and corticosteroids provide symptomatic relief but do not address the cause

Welfare Considerations

RAO significantly impairs welfare through chronic respiratory effort, reduced exercise tolerance, and the physical distress of labored breathing. The characteristic heave line — a hypertrophied abdominal muscle from chronic forced expiration — reflects sustained respiratory work. Welfare-centered management requires eliminating dust exposure: soaking or steaming hay, providing rubber matting or paper bedding instead of straw, and maximizing turn-out. Horses at pasture rarely suffer RAO flares.

What You Can Do

• Soak hay for 30 or more minutes or feed steamed hay to eliminate dust and mold spores
• Replace straw bedding with dust-free alternatives: rubber matting, cardboard, or wood shavings
• Maximize turnout — horses at pasture have dramatically lower RAO flare rates
• Improve stable ventilation — open windows and avoid adjacent hay storage
• Work with your vet on a corticosteroid and bronchodilator protocol for flare management