Equine Heaves (RAO): Chronic Airways Disease in Horses
Heaves is asthma for horses — an allergic lung condition causing cough and breathing difficulty. Management keeps horses working.
Recurrent airway obstruction (RAO), commonly called heaves or broken wind, is a chronic allergic respiratory disease of horses. It's similar to human asthma and causes airway inflammation, bronchospasm, and mucus accumulation. With proper management, most horses continue athletic careers.
Key Points
- RAO affects mature horses, usually over 7 years
- The primary trigger is dust and mold in hay and bedding
- Signs include chronic cough, nasal discharge, and increased breathing effort
- The 'heave line' — a visible ridge of abdominal muscles — develops in chronic cases
- Management focuses on dust control; medications treat flare-ups
- Corticosteroids and bronchodilators are the main medical treatments
Understanding RAO
RAO is an allergic, hypersensitivity reaction to inhaled organic dust. The airways become inflamed and constricted. Neutrophils infiltrate the airway walls. Mucus glands overproduce, clogging small airways. Smooth muscle hypertrophy narrows the airway lumen. The result is obstructed airflow, especially during expiration. The disease is progressive if exposure continues. Some horses develop irreversible airway remodeling.
Management & Treatment
Environmental management is the most critical aspect. Replace hay with haylage, silage, or soaked hay. Use low-dust bedding. Avoid straw and shavings from softwood. Stable in well-ventilated areas. Keep horses outside as much as possible. Corticosteroids (dexamethasone, prednisolone, or inhaled beclomethasone/fluticasone via EquineHaler) reduce airway inflammation. Bronchodilators (clenbuterol, albuterol) provide immediate relief during acute episodes.
When to See a Vet Immediately
- Your horse has a chronic cough at rest and during exercise
- Exercise intolerance is worsening
- There's increased breathing effort with an abdominal push
- A heave line is visible along the flank
- The horse is stabled in a dusty environment with dry hay
How RVC Can Help
This article is for educational purposes only and does not replace professional veterinary advice. If your pet is showing any symptoms, please contact Royal Veterinary Center immediately at +853 6677 6611.