Respiratory issues and asthma (COPD) in horses
Respiratory issues and asthma (COPD) in horses: causes, environmental management and treatment options with strong scientific evidence.
Short & honest
Equine asthma is manageable but not curable. Environmental management is the cornerstone; medication supports but only works optimally in combination. Strong evidence (A).
Veterinary review not yet completed
This page is awaiting review by a registered veterinary surgeon. Until then, treat the text as education based on the sources listed — not as a verified veterinary judgement.
What is equine asthma?
Equine asthma is the current umbrella term for chronic respiratory diseases in the horse, and replaces older terms such as COPD, heaves and RAO [3]. The condition has two forms:
- IAD (Inflammatory Airway Disease) — mild form, often in sport horses; coughing and reduced performance without pronounced dyspnoea at rest.
- SEA (Severe Equine Asthma) — severe form; clear dyspnoea even at rest, enlarged abdominal muscles due to effort during exhalation.
The distinction determines the treatment intensity and the urgency of veterinary supervision.
Environmental management: the absolute cornerstone
Exposure to mould spores and respirable dust is the primary trigger. Environmental adjustments are not an 'extra measure' but a prerequisite for any treatment success [2]:
| Measure | Effect |
|---|---|
| Switch from hay to haylage or steamed hay | Reduces respirable dust by 70–99% [2] |
| Replace straw with wood shavings or pellets | Straw strongly increases dust load; alternatives significantly better [2] |
| Stable outdoors or in a loose housing system | Reduces accumulation of ammonia and spores |
| Neighbours in the same stable also adapt | Shared airborne dust cancels out individual measures |
Glucocorticoids usually do not normalise airway neutrophilia unless environmental management is implemented simultaneously — both interventions are necessary [1].
Pharmacological treatment
Corticosteroids
Glucocorticoids (such as dexamethasone systemically or fluticasone/beclomethasone via inhalation) reliably relieve airway obstruction [1]. The inhalation route is preferred: comparable efficacy with fewer systemic adverse effects, including a lower risk of iatrogenic laminitis [1]. Long-term treatment with inhaled fluticasone reduces smooth muscle mass in the airways by approximately 30% over two to three months; however, cure does not occur [1].
Bronchodilators
Salbutamol or clenbuterol are used for acute airway constriction. In a severe attack, combination with corticosteroids is indicated for the fastest improvement [3]. Do not use bronchodilators as a replacement for anti-inflammatory treatment.
Remission and relapse
Remission is achievable, but not permanent. Any re-exposure to mould spores or dust — even short-term — can trigger a relapse [2]. This makes lifelong environmental management necessary, regardless of whether the horse is free of medication.
Supplementary and natural options
There is no good evidence that herbal supplements, homeopathy or other alternative remedies reliably reduce airway inflammation in equine asthma. Environmental management and, where necessary, veterinary medication are the only interventions with proven effect [1][2][3]. Additional measures such as stress reduction and optimal ventilation can support welfare, but do not replace proven treatment.
Supplementary ≠ substitutive
All treatment options on this page are supplementary to — never a replacement for — veterinary care. In case of respiratory complaints, a diagnosis is essential: infectious causes (bacterial, viral) require a completely different approach than allergic/inflammatory asthma.
Why this verdict?
The evidence base consists of multiple controlled clinical studies, narrative reviews in peer-reviewed journals and guidelines from the Merck Veterinary Manual [1][2][3]. Limitations are the relatively small study populations and the chronic nature of the condition, resulting in scarce long-term data. The consistency of findings regarding environmental management and corticosteroids justifies a grade A.
Interactions with medication
- Systemic corticosteroids increase the risk of laminitis, particularly in horses with existing metabolic disorders (EMS, PPID) — always discuss this with the veterinary surgeon
- Concurrent use of bronchodilators and corticosteroids: effective combination for acute attacks, but requires veterinary supervision
Legal status (Netherlands)
Fluticasone, beclomethasone, dexamethasone, salbutamol and clenbuterol are prescription-only veterinary medicinal products in the Netherlands. Clenbuterol is on the doping list for sport and competition horses.
Sources
- [1] Glucocorticoid treatment in horses with asthma: A narrative review. Journal of Veterinary Internal Medicine, 2021. Narrative review doi:10.1111/jvim.16189
- [2] Environmental Management of Equine Asthma. Animals (Basel), 2024. Narrative review doi:10.3390/ani14030446
- [3] Asthma in Horses — Merck Veterinary Manual. Merck Veterinary Manual. Guideline source ↗