Nebulisation of dexamethasone sodium phosphate for the treatment of severe asthmatic horses.

The research was focused on understanding the impact of dexamethasone administered via nebulisation versus orally in the treatment of severe asthma in horses. The results suggested that despite its popularity, dexamethasone nebulisation did not provide significant progress in enhancing lung function in the sample studied.

Objective and Hypothesis

• The key objective of this research was to ascertain the effects of dexamethasone nebulisation on lung function in severe asthmatic horses. The hypothesis stated that dexamethasone administered by nebulisation would be more effective than the same dose given orally.

Research Methodology

• A randomised blinded experimental study design was used.
• There were 12 severe asthmatic horses in clinical exacerbation which were randomly divided into two groups.
• One group was treated with 5 mg of dexamethasone sodium phosphate by nebulisation while the other was treated orally with the same dosage, for 7 days.
• Lung functions were evaluated at baseline, after four treatment days (D4), and 24 hours after the last dose (D8).
• The presence of residual bronchospasm was assessed on D8 with N-butylscopolammonium bromide administration.
• The horses underwent respiratory clinical scoring daily, and their serum cortisol concentration was measured at predetermined intervals.

Results of the Study

• The study revealed that while the pulmonary elastance was unchanged in both groups, pulmonary resistance showed significant improvement in the oral group on D8.
• All horses were found to have residual bronchospasm at the completion of the study.
• A significant reduction in respiratory clinical score was noticed in the oral group from D5 to D8.
• Interestingly, the serum cortisol concentration level decreased in all horses.

Conclusions

• The research concluded that depending on the lack of improvement in lung function and the suppression of the hypothalamic-pituitary-adrenal axis, aerosolisation of an injectable form of dexamethasone for the treatment of severe equine asthma at the investigated dose and with the evaluated nebuliser is not supported by this study.
• The study emphasised that the low number of horses used in the study and the absence of a placebo group were limitations that needed consideration.