Pulmonary function and adrenal gland suppression with incremental doses of aerosolized beclomethasone dipropionate in horses with recurrent airway obstruction.

This research studied the impact of varying doses of beclomethasone, a steroid, in horses with respiratory issues. It found that all doses improved respiratory function, and that higher doses also improved lung compliance but caused a greater decrease in cortisol production.

Research Methodology

• The study was a crossover trial involving 8 horses suffering from recurrent airway obstruction, a condition similar to asthma in humans.
• The horses were randomly allocated to four groups, which were treated with either a placebo or one of three doses of beclomethasone (500, 1,000 or 1,500 micrograms).
• The medication was administered via aerosol inhalation twice daily, and a washout period of at least 10 days was observed in between different treatment phases to eliminate residual effects.
• Several measurements were taken daily before the morning dose being administered, including an assessment of airway obstruction, serum cortisol concentration, and the maximum change in pleural pressure during normal breathing (delta Pplmax).
• Delta Pplmax was assessed again 15 minutes after administration of the morning dose, and further measurements of pulmonary resistance and dynamic compliance were taken at baseline and approximately 12 hours after the final treatment.

Key Findings

• No immediate effect was observed following beclomethasone administration.
• However, within 24 hours, delta Pplmax and airway obstruction were found to be lower in horses receiving the beclomethasone treatments.
• The onset and magnitude of response were comparable among the three dosage groups.
• All doses of beclomethasone improved pulmonary resistance, and the larger doses (1,000 and 1,500) also improved dynamic compliance, which measures how easily lungs can expand.
• All dosages also reduced serum cortisol, a stress hormone produced by the adrenal gland, with the magnitude of this effect being greater in horses given the higher doses of 1,000 and 1,500 micrograms. This indicates some degree of adrenal gland suppression, a potential side effect of steroid treatment.

Conclusions

• The low-dose beclomethasone (500 micrograms) was just as effective at improving pulmonary function as the higher doses.
• The only exception to this was dynamic compliance, which was improved only after administration of the higher doses (1,000 and 1,500 micrograms).
• The low-dose administration resulted in less suppression of naturally occurring cortisol production, suggesting lower potential side effects with this dosage.

In conclusion, beclomethasone presents as an effective treatment for horses with recurrent airway obstruction, achieving improved respiratory function without significant immediate side effects. While all doses were beneficial, the lower dose of 500 micrograms appears preferable due to its similar effectiveness and lower potential for suppression of cortisol production.