Nebulized dexamethasone sodium phosphate in the treatment of horses with severe asthma.
Authors: de Wasseige Selena, Picotte Khristine, Lavoie Jean-Pierre
Journal: Journal of veterinary internal medicine
Summary
# Nebulized Dexamethasone for Equine Asthma: Oral Route Remains Superior When treating horses with severe asthma, clinicians have long sought effective delivery methods that might minimise systemic corticosteroid exposure, making nebulised dexamethasone an intuitively attractive option. De Wasseige and colleagues conducted a randomised trial comparing nebulised dexamethasone sodium phosphate (5 mg daily via Flexineb mask) against oral administration over seven days in twelve horses with severe asthma, measuring lung function and serum cortisol suppression at baseline, day 4 and day 8. Only the oral group demonstrated significant improvements in lung resistance (−1.5 to −1.4 cm H₂O/L/s reduction; P = .004–.01), whilst both routes effectively suppressed cortisol, indicating that systemic absorption occurred from nebulisation without conferring therapeutic benefit to the airways. These findings suggest that nebulised dexamethasone, despite circumventing hepatic first-pass metabolism, fails to achieve sufficient local airway concentrations in severely affected horses and should not replace oral therapy—a sobering reminder that convenient drug delivery does not guarantee clinical efficacy, and practitioners should maintain oral corticosteroids as the standard for managing equine asthma exacerbations.
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Practical Takeaways
- •Oral dexamethasone remains the preferred treatment for severe equine asthma; nebulization via Flexineb mask should not be relied upon as an alternative despite systemic absorption
- •Both delivery routes suppress the HPA axis, so practitioners must monitor for adrenal suppression risks and plan appropriate tapering protocols
- •The lack of efficacy of nebulized treatment despite cortisol suppression suggests poor lung bioavailability; clinicians should stick with proven oral protocols rather than attempting nebulized corticosteroids for asthma management
Key Findings
- •Oral dexamethasone significantly improved lung resistance at day 4 (mean decrease -1.5 cm H₂O/L/s) and day 8 (-1.4 cm H₂O/L/s), but nebulized dexamethasone did not show significant improvement
- •Both nebulized and oral dexamethasone significantly suppressed serum cortisol concentrations at days 4 and 8 (maximum decreases of -1.2 to -2.2 μg/dL)
- •Despite cortisol suppression, nebulized dexamethasone via Flexineb mask was not effective for treating severe asthma in horses, contradicting earlier assumptions about its efficacy