Low-intensity exercise may ease airway resistance in severe equine asthma
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A new study in Equine Veterinary Journal reports that low-intensity exercise, performed in a field-applicable way, induced measurable bronchodilation in horses with severe equine asthma. According to the PubMed record for the paper, pulmonary resistance dropped from 2.6 to 1.3 cm H2O/L/s after exercise, a roughly 50% reduction, while a turnout intervention did not produce the same effect. The authors frame that response as comparable to bronchodilator therapy, pointing to a potentially useful physiologic effect from a management tool that’s already available in practice. (pubmed.ncbi.nlm.nih.gov)
The finding lands in a clinical area where veterinarians have long balanced medication with intensive environmental control. Severe equine asthma is a chronic, noninfectious inflammatory lower-airway disease marked by airway inflammation, bronchospasm, mucus accumulation, and, over time, airway remodeling. Experts cited by The Horse note that hay and barn dust are central triggers for many affected horses, and that even visually good-quality hay can still carry molds and other inhaled irritants capable of provoking disease. (thehorse.com)
That background helps explain why the new exercise result is notable. Exercise is often discussed in terms of performance limitation or symptom provocation, yet this study suggests that submaximal aerobic work may also produce a short-term bronchodilatory effect in horses with severe disease. Based on the abstracted study details available through PubMed, the effect was seen after exercise but not after turnout alone, which strengthens the argument that the response is tied to exercise physiology rather than simple movement or time outside. (pubmed.ncbi.nlm.nih.gov)
At the same time, the broader literature still points back to environmental management as the main lever for disease control. In a separate 2025 Equine Veterinary Journal study, steamed hay, a common strategy meant to reduce respirable particles, did not outperform dry hay in preventing deterioration in horses with severe equine asthma in remission. Over four weeks, airway resistance and bronchoalveolar lavage neutrophils increased significantly over time, and the authors concluded that steamed hay caused mild but significant worsening, with no significant difference versus dry hay in that study setting. Related prior work has found better outcomes when horses are moved to lower-dust forage options such as pellets, pasture, or other feeding strategies that reduce breathing-zone exposure. (pubmed.ncbi.nlm.nih.gov)
Industry and expert commentary around equine asthma has been consistent on one point: bronchodilation alone isn’t enough. Jean-Pierre Lavoie has previously emphasized that bronchodilators should not be used as sole therapy because they do not control the inflammatory process, and The Horse summarized evidence that corticosteroids and bronchodilators may work synergistically in some cases. That makes the new exercise paper clinically interesting, but also easy to overread if it’s stripped of context. A transient reduction in pulmonary resistance is not the same thing as disease control. (thehorse.com)
Why it matters: For veterinary professionals, the study may open a practical conversation about whether carefully selected low-intensity exercise could serve as an adjunct in stable horses with severe asthma, especially where medication timing, competition rules, cost, or pet parent preferences complicate management. But it also reinforces how multimodal this disease is. Horses with severe asthma need reduced aeroallergen exposure in the breathing zone, and many will still require anti-inflammatory therapy. In that sense, exercise may prove to be one more tool for symptom modulation, not a replacement for core management. (thehorse.com)
What to watch: The key next steps are replication, longer-term follow-up, and field studies that test whether repeated low-intensity exercise improves clinical scores, reduces medication needs, or changes relapse risk. It will also be important to define which horses are appropriate candidates, since severe equine asthma can include hypoxemia, pulmonary hypertension, and marked exercise intolerance during exacerbations. (thehorse.com)