Pulmonary function in horses with recurrent airway obstruction after aerosol and parenteral administration of beclomethasone dipropionate and dexamethasone, respectively.

The research investigates the effect of aerosol and parenteral administration of beclomethasone dipropionate and dexamethasone respectively on horses with recurrent airway obstruction or ‘heaves’. The study indicates that both methods improved symptoms and pulmonary function of the horses, but parenteral administration seemed to have a more pronounced effect.

Research Methodology

• Six horses with inducible and reversible ‘heaves’ were part of this study.
• ‘Heaves’ or episodes of recurrent airway obstruction were induced in these horses by exposure to moldy hay and straw for 7 days.
• Horses were assigned to various treatment groups – those receiving aerosolized beclomethasone dipropionate, some that were administered dexamethasone parenterally, and a control group receiving aerosolized propellant.
• Daily evaluations included measuring respiratory frequency and a subjective assessment of respiratory effect. Additionally, changes in pleural pressure (∆Pplmax), pulmonary resistance (RL), and dynamic compliance (Cdyn) were mapped over days 0, 7, 10, 14, and 21 of the study.

Research Findings

• All horses exhibited increased pulmonary resistance and pleural pressure, and decreased dynamic compliance in response to the challenge of exposure to moldy hay and straw.
• Administration of beclomethasone reduced pulmonary resistance by day 10, decreased change in pleural pressure on days 14 and 21, and brought about an increase in dynamic compliance on day 14.
• For horses treated with dexamethasone, pulmonary resistance and pleural pressure were reduced, while dynamic compliance was increased on days 10, 14, and 21.
• From subjective evaluations, an improvement in respiratory effort was noted within 2 and 3 days of administering beclomethasone and dexamethasone. However, these improvements regressed to initial values within 1 and 3 days, respectively, after discontinuing the drugs.

Research Conclusion

• Pulmonary function was improved in horses suffering from recurrent airway obstruction by using both beclomethasone and dexamethasone.
• The study found that the response to aerosolized beclomethasone was generally less marked than that achieved with the parenterally administered dexamethasone. For this reason, the researchers concluded that it might be beneficial to increase the dose or frequency of aerosolized beclomethasone to match the anti-inflammatory response observed in the use of parenterally administered dexamethasone.