Efficacy of dexamethasone, salbutamol, and reduced respirable particulate concentration on aerobic capacity in horses with smoke-induced mild asthma.
Authors: Bond Stephanie L, Greco-Otto Persephone, MacLeod Jacqueline, Galezowski Angelica, Bayly Warwick, Léguillette Renaud
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Efficacy of Dexamethasone, Salbutamol, and Reduced Respirable Particulate Concentration on Aerobic Capacity in Horses with Smoke-Induced Mild Asthma Mild asthma substantially impairs equine athletic performance through compromised gas exchange, yet the therapeutic efficacy of standard interventions remains poorly characterised. This prospective, randomised, placebo-controlled trial enrolled twelve Thoroughbred polo horses exposed to elevated particulate matter (PM2.5 of 35.51 μg/m³) from bushfire smoke over a 33-day period, providing a naturalistic model of mild asthma; horses underwent V̇O₂ peak testing at baseline, after dexamethasone or saline treatment under improved air quality (PM2.5 reduced to 7.04 μg/m³), and following inhaled salbutamol administration, with bronchoalveolar lavage and mucus scoring performed at designated timepoints. Peak aerobic capacity improved significantly by 15.5 ± 4.0 mL/(min·kg) from baseline to day 17—a clinically meaningful 13.2% increase—whilst airway mucus scores improved by 1.27 ± 0.38 points; notably, no difference existed between dexamethasone and saline treatment groups, suggesting environmental control was the primary therapeutic driver. These findings underscore that environmental management—specifically reduction of respirable particulate exposure—represents the critical intervention for mild asthma, potentially providing stronger justification to horse owners and operators for investing in stable air quality rather than relying solely on pharmacological management. Practitioners should contextualise their treatment recommendations within the broader framework of dust and particulate control; this evidence may substantially improve client
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Practical Takeaways
- •Air quality management is more critical than pharmacological treatment alone for horses with mild asthma; reducing smoke and particulate exposure should be the primary intervention strategy
- •Owners of asthmatic horses must understand that environmental control significantly impacts aerobic performance and racing capacity—use this evidence to support recommendations for improved stable ventilation and reduced smoke exposure
- •Dexamethasone treatment alone did not provide additional benefit over environmental improvement, suggesting cost-effective management prioritizes barn management before escalating medication protocols
Key Findings
- •VO₂ peak increased by 13.2% (15.5 ± 4.0 mL/min·kg) from baseline to day 17 following reduced particulate matter exposure and treatment (P = 0.002)
- •Mucus scores improved significantly by 1.27 ± 0.38 points between day -8 and day 20 (P = 0.01)
- •No significant difference in VO₂ peak response between dexamethasone and saline treatment groups at any timepoint
- •Improved ambient air quality (PM2.5 reduction from 35.51 to 7.04 μg/m³) was the primary driver of performance improvement in mild asthma