New findings on equine asthma and why management at competitions matters
For many horses, show environments, rather than being optimal for performance, carry hidden risks to their respiratory health. Increasingly, research is pointing to inflammatory airway disease (IAD) and equine asthma as leading causes of reduced performance in sport horses, often triggered or worsened by the very conditions found at competition venues.
The anatomy
The horse’s respiratory system is uniquely adapted to meet the demands of athletic performance. Unlike humans, horses are obligate nasal breathers, which means they can only breathe through their noses. This is why their nasal passages are exceptionally large and able to expand during intense exercise, maximising the volume of air they can take in.
When a horse breathes in, air travels down a long nasopharynx (throat), where it passes over delicate turbinates. These intricate bony structures clean, warm, and humidify the air before it reaches the lungs.
From there, the air moves past the larynx into the trachea, a flexible tube supported by C-shaped cartilage rings to keep it open. The lining of the trachea is covered in mucus and tiny hair-like cilia, which help trap dust and debris, moving them back out of the airway.
For clarity, the equine respiratory tract is usually divided into two main sections:
- Upper respiratory tract: the nostrils, nasal passages, pharynx, larynx, and the upper part of the trachea.
- Lower respiratory tract: the lower trachea and the lungs, which are housed within a thin protective sac called the pleural space.
Equine respiration
When a horse inhales, air moves down the trachea, which branches into the right and left bronchi. These divide further into smaller passageways called bronchioles, ending in tiny sacs known as alveoli. It is here, across a delicate membrane only a single cell thick, that the vital exchange of gases takes place: oxygen enters the bloodstream, while carbon dioxide – the main by-product of metabolism – is removed.
The respiratory system’s primary role is therefore twofold: to deliver oxygen to the blood so it can fuel every cell in the body, and to expel carbon dioxide so waste gases do not accumulate.
At rest, a healthy horse breathes around 10–15 times per minute, drawing in roughly four to six litres of air with each breath. But during strenuous work, this system is pushed to its limits. A fit equine athlete may exchange as much as 1800 litres of air per minute, meeting the enormous oxygen demands of high-level performance.
Built-in protective mechanisms help safeguard this finely tuned process. As air passes through the nasal passages, it is warmed and humidified, while larger particles are trapped in mucus and expelled through swallowing or coughing. Smaller particles are dealt with by the immune system before they can reach the lungs.
When infection, inflammation, or environmental challenges overwhelm these defences, however, the result is respiratory disease – a condition that impairs gas exchange, reduces performance, and compromises a horse’s overall wellbeing.
From stable cough to equine asthma
Respiratory problems in horses were once brushed off as stable coughs or seasonal irritations. Today, vets recognise a spectrum of disease – from mild, often subclinical inflammation (inflammatory airway disease (IAD)) through to the more severe and chronic form, severe equine asthma (previously termed recurrent airway obstruction or ‘heaves’).
Even mild inflammation can cause:
- intermittent cough,
- nasal discharge,
- subtle changes in recovery times,
- or a drop in performance long before overt signs appear.
At high-stakes shows, even these ‘small’ issues can be the difference between a clear round and a refusal.
Why shows compromise respiratory health
Recent studies have highlighted the role of environmental triggers common at competitions:
- Dust and particulates: Bedding in temporary stables, nearby arenas, and dry footing release airborne irritants.
- Pathogens in close quarters: Travelling and stabling horses from multiple yards together increases exposure to viruses and bacteria.
- Stress and transport: Long journeys compromise the mucociliary clearance of the airways, making horses more vulnerable to inhaled particles and infections.
- Poor ventilation:Pop-up or temporary stables often have restricted airflow, concentrating dust and ammonia.
Did you know?
One Canadian study found that horses stabled at shows showed measurable increases in airway inflammation within just a few days, compared to the same horses at home. Even horses without a prior history of respiratory disease can be affected.
New insights: Omega-3s, dust control, and early detection
The science of equine asthma management is moving forward:
- Nutritional support: Trials with omega-3 fatty acid supplementation (EPA/DHA) have shown improved clinical scores and airway cell counts in horses with mild asthma when combined with low-dust forage management.
- Dust suppression: Research confirms that soaked or steamed hay and low-dust bedding significantly reduce respirable particles, even in temporary stabling.
- Environmental monitoring: New devices can now measure airborne dust and ammonia at events, helping organisers improve ventilation and footing choices.
- Early diagnosis: Portable endoscopy and non-invasive lung function tests are making it easier to identify horses with airway inflammation before obvious symptoms appear.
Top tip
Be careful how you store your hay at shows, particularly when steaming and soaking, as hay left damp for too long can become mouldy. Even small amounts of mould can release spores that irritate the airways, trigger coughing and exacerbate respiratory conditions.
Practical takeaways
Forage first, but always dust controlled
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- Travel with pre-steamed or soaked hay if possible.
- Avoid feeding hay from the ground in dusty stables or arenas.
Stable management
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- Bed on low-dust options (wood shavings or paper) rather than straw.
- Keep stables well ventilated, with doors and windows open where safe.
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Travel hygiene
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- Keep travel time as smooth as possible. Regular stops to lower heads and clear airways can help reduce post-transport inflammation.
Warm-up with care
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- Give horses time to clear their lungs before high-intensity work, especially after long journeys.
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Monitor subtle signs
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- A small cough in warm-up or slower recovery can be an early warning sign. Don’t ignore it.
Good hygiene practices
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- Disinfect buckets and feed tubs daily to reduce the spread of bacteria and viruses while away at a show.
- Avoid sharing equipment such as water hoses, grooming brushes, or bits between horses from different yards.
- Wash your hands or use sanitiser before and after handling horses.
- Keep bedding and muck heaps tidy around stabling areas to minimise ammonia build-up and insect infestations.
Vaccinations and preventative measures
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- Ensure flu vaccinations are up to date well before travelling, as immunity takes time to build.
- Follow FEI or show regulations on vaccination intervals, but think beyond minimum compliance. Discuss with your veterinarian whether additional boosters or tailored schedules make sense for your competition horse.
- Remember: a single unprotected horse can put an entire yard at risk – vaccination is both a performance safeguard and a welfare responsibility.
What this means for the sport
As competition schedules intensify, respiratory health is becoming one of the most important welfare and performance considerations in modern equestrian sport. For organisers, it means investing in better stable design and footing choices. For riders, it means becoming proactive managers of the horse’s environment, even when away from home.
Equine asthma may not carry the drama of a tendon injury or colic, but its effects on athletic performance are just as significant. With good management, however, it is one of the most preventable and controllable conditions in the competition horse.
In summary
New science confirms what experienced horse owners have long suspected: the show environment challenges the equine respiratory system in unique ways. By combining evidence-based nutrition, dust control, and vigilant management, riders can help their horses breathe easier and perform at their potential in competition.