The airway response of horses with recurrent airway obstruction (heaves) to aerosol administration of ipratropium bromide.

This research aimed to study the response of horses with recurrent airway obstruction (RAO), also known as heaves, to an inhaled treatment of ipratropium bromide, a medication often used to manage chronic pulmonary conditions in humans.

Research Approach

• The researchers conducted their study on eight horses identified with RAO. Ipratropium bromide was observed as a potential therapy for improving equine respiratory health.
• To ensure the airway obstruction was reversible in the selected horses, researchers measured lung function both before and during stabling. They also gauged responses to atropine administration.
• The dosage response to ipratropium bromide was tested using an experimental design called the Williams square design. This statistical measure is often effective in resource-limited settings, as it reduces bias and variance.
• The varying dosage included 25, 50 or 75 micrograms/ml of ipratropium bromide. It was implemented via nebulisation, a common method for administering medication directly to the lungs.

Results and Findings

• The researchers noted that the aerosol vehicle (the substance used to carry the ipratropium bromide into the horse’s airways) had no impact on lung function.
• Significant changes were observed when the horses were treated with ipratropium bromide. It decreased the maximal change in pleural pressure during tidal breathing (delta Pplmax) and pulmonary resistance (RL), while increasing dynamic compliance (Cdyn), a metrics indicating the lungs’ elasticity or its ability to expand and contract.
• Dose-dependent effects on RL and Cdyn were tracked at the 1-hour post-nebulization mark. This means the medication’s effects varied depending on the dose given.
• Finally, a separate experiment revealed that the ipratropium bromide’s effects were long-lasting, between 4 to 6 hours.

Conclusion

• This study suggested that ipratropium bromide could be a potential therapy for horses with RAO, showing notable improvement in lung function metrics after aerosol administration.