High severity

Equine Asthma (RAO / COPD)

Equine asthma — also called Recurrent Airway Obstruction or 'heaves' — is a chronic respiratory disease triggered by inhaled allergens (dust, mould, pollen). Affected horses have breathing difficulty, chronic cough, and reduced performance.

Symptoms to watch for

Persistent dry cough, especially at the start of exercise or feeding

Increased respiratory effort at rest

Visible 'heave line' along the abdomen from accessory muscle use

Nasal discharge — clear, white, or yellow

Exercise intolerance

Flared nostrils at rest

Symptoms worsen in dusty stables or when fed dry hay

Common causes

Inhaled mould spores from dusty hay or bedding
Pollens (summer pasture-associated form)
Poor stable ventilation
Ammonia from urine-soaked bedding
Genetic predisposition

Prevention

Soak hay for 30 minutes before feeding, or feed haylage/silage
Use dust-extracted bedding (cardboard, hemp, rubber matting with shavings)
Maximise turnout — fresh air is the best treatment
Improve stable ventilation: open windows, install vents
Wet down arena footing if working indoors
Move horse outside while mucking out and during hay distribution
Avoid round bales and overhead hay storage

What to do

1
Confirm diagnosis with vet — endoscopy and bronchoalveolar lavage.
2
Implement strict environmental management (low-dust forage and bedding).
3
Administer prescribed bronchodilators (clenbuterol) and inhaled corticosteroids.
4
Monitor breathing rate daily — alert vet if respiratory rate exceeds 16/min at rest.
5
Maintain a winter feeding plan that avoids dusty hay.
6
Re-evaluate every 3–6 months to adjust medication.

When to call the vet

Pick up the phone if…

Call the vet promptly if your horse shows persistent cough, laboured breathing, or exercise intolerance. Severe attacks (heave line, flared nostrils, respiratory distress) require emergency treatment.

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Educational content only. Not a substitute for veterinary advice.