Environment and prednisone interactions in the treatment of recurrent airway obstruction (heaves).
Authors: Jackson C A, Berney C, Jefcoat A M, Robinson N E
Journal: Equine veterinary journal
Summary
# Editorial Summary: Environment and Prednisone in Recurrent Airway Obstruction Recurrent airway obstruction (heaves) develops in susceptible horses exposed to dust, moulds, and spores; whilst pasture turnout typically resolves clinical signs, this is often impractical for owners. Jackson and colleagues investigated whether environmental modification of a single stall—changing from straw bedding and hay to wood shavings and pelleted feed—could improve lung function in RAO-affected horses, and whether concurrent oral prednisone (2.2 mg/kg daily) provided additional benefit. Twelve RAO-susceptible horses were monitored with lung function testing and bronchoalveolar lavage over 14 days of environmental modification, with or without prednisone, followed by 30 days at pasture. Environmental changes alone produced significant improvements in airway obstruction and lung function within just 3 days, with further gains by day 7; prednisone accelerated the reduction in inflammatory cell numbers (neutrophils and total cells) by day 3, yet did not significantly enhance functional improvements compared to environmental modification alone. These findings underscore that allergen reduction must be the primary treatment focus for RAO, and whilst corticosteroids may help control inflammation more rapidly, they do not translate into faster restoration of airway function—a crucial distinction for practitioners counselling clients on realistic timelines and treatment priorities.
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Practical Takeaways
- •Environmental management (reducing dust and mould exposure through bedding and feed changes) should be the primary treatment strategy for RAO, as significant clinical improvement occurs within 3 days without medication
- •While prednisone reduces inflammation markers more rapidly, it does not speed up functional improvement in airway obstruction—focus resources on stable management rather than solely on corticosteroid therapy
- •Even modifying a single stall's environment in a multi-stall barn can benefit RAO-affected horses, making this approach practical for facilities where full pasture turnout is not feasible
Key Findings
- •Significant improvement in lung function occurred within 3 days of environmental modification alone (changing bedding to wood shavings and feeding pelleted diet)
- •Environmental modification alone improved airway function comparably to environmental modification plus prednisone at 2.2 mg/kg daily
- •Prednisone accelerated reduction in airway inflammation (neutrophils decreased by Day 3 with prednisone vs. Day 14 without) but did not translate to faster improvement in lung function
- •Airway function was best after 30 days at pasture, demonstrating that allergen reduction is the cornerstone of RAO treatment