Recurrent Airway Obstruction in Horses: Managing Equine Heaves

Recurrent airway obstruction (RAO), formerly called heaves or COPD, is a common allergic respiratory disease in horses. Proper environmental management and treatment can dramatically improve quality of life for affected horses.

Key Facts

RAO is an equine inflammatory airway disease caused by hypersensitivity to inhaled allergens — primarily mould spores in hay and bedding.
Affected horses show nasal discharge, coughing, increased respiratory effort, flared nostrils, and the characteristic "heave line" (hypertrophied abdominal muscle from chronic forced expiration).
Severe RAO causes significant respiratory distress: horses may show a respiratory rate above 30 breaths per minute at rest with marked effort on expiration.
A summer-onset variant (Summer Pasture-Associated RAO) affects some horses when at grass, caused by outdoor fungal and pollen allergens.
The primary welfare and management intervention is environmental: soaking or steaming hay reduces spore content by up to 98%; deep-litter shavings or rubber matting with no bedding minimise dust exposure.
Bronchodilators (clenbuterol) and corticosteroids (dexamethasone, inhaled fluticasone) provide significant symptomatic relief.
Inhaled medication delivery via equine nebulisers and spacers achieves bronchial drug deposition with lower systemic side effects than systemic corticosteroids.
Horses with RAO that are managed in low-dust environments with appropriate medication can often remain in full work with good quality of life.

Welfare Considerations

RAO causes genuine respiratory distress that significantly impairs welfare in affected horses. Chronic dyspnoea (difficulty breathing) is a highly aversive experience; horses with severe uncontrolled RAO show behavioural signs of distress including reluctance to move, sweating, and anxious expression. The effort involved in each breath when bronchoconstriction is severe causes fatigue and prevents normal rest and sleep. Long-term poorly managed RAO leads to structural lung damage and potentially irreversible airway remodelling. The good news for welfare is that appropriate environmental management — the single most impactful intervention — is achievable on virtually all yards and significantly reduces the frequency and severity of exacerbations. Horses managed in clean-air environments, even without medication, show dramatic improvements in respiratory comfort.

What You Can Do

Soak or steam hay for RAO-affected horses for 30-60 minutes before feeding to reduce mould spore content.
Switch to dust-free bedding (rubber matting, paper bedding, or low-dust shavings) and avoid deep-litter straw for affected horses.
Maximise turnout — fresh air dramatically reduces allergen exposure compared to even well-ventilated stabling.
Discuss inhaled corticosteroid and bronchodilator therapy with your vet — inhaled medications have fewer side effects than systemic drugs.
Feed hay from ground level or nets positioned low — reducing the height from which dust falls toward the respiratory tract.