Use of a hand-held, metered-dose aerosol delivery device to administer pirbuterol acetate to horses with ‘heaves’.

This research article investigates the effectiveness of aerosol administration of the bronchodilator, pirbuterol acetate, through a novel hand-held, metered-dose inhaler to horses diagnosed with ‘heaves’, which is a common airway disease in horses. The study found that this mode of administration was not only effective and safe, but also convenient.

Methodology

• The study was carried out using six horses predisposed to ‘heaves’, an airway disease.
• To induce airway obstruction, the researchers stabled these horses, placed them on straw bedding, and fed them hay. They ensured airway obstruction was present by observing if the maximum change in pleural pressure during tidal breathing was greater than 20 cmH2O for two consecutive days.
• Pulmonary function was then monitored before, and at various times (ranging from 5 minutes to 7 hours) after administering aerosol pirbuterol.
• The drug was administered using a metered canister and a specially designed hand-held device inserted into the horse’s left nostril.
• Control samples were also taken using a vehicle agent to compare with the effect of the drug. The dosages ranged from 400 to 1600 micrograms.

Results

• Observations indicated relief of airway obstruction within 5 minutes after administering both the vehicle and pirbuterol.
• Drops in delta Pplmax (an indicator of the degree of airway obstruction) and pulmonary resistance as well as increases in dynamic compliance persisted for the 7-hour duration of the experiment.
• Comparison of vehicle and pirbuterol effects revealed that pirbuterol significantly reduced both pulmonary resistance and delta Pplmax for up to 1 hour.
• The researchers determined that the optimal dose for administration was 600 micrograms.

Conclusion

• The study determined that aerosol pirbuterol is an effective and safe bronchodilator treatment for horses with ‘heaves’.
• Given the immediate response to treatment, degree of drug effect, and absence of noticeable side effects, it appeared to be a beneficial treatment method.
• The hand-held, metered-dose aerosol delivery device was found exceptionally convenient and effective, and researchers recommended its use for delivering therapeutic aerosols to horses.