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

The research study is aimed at evaluating the changes in the adrenal gland’s function in horses suffering from recurrent airway obstruction after being treated with beclomethasone dipropionate in an aerosolized form and dexamethasone via parental administration.

Methodology

• For the research, six horses with inducible and reversible recurrent airway obstruction, also referred to as “heaves”, were used. Their episodes of heaves were triggered intentionally by exposing them to moldy hay and straw for a period of seven days, known as a natural challenge.
• After triggering the heaves, they were treated with aerosolized beclomethasone, parenterally administered dexamethasone, and aerosolized propellant for seven days. The horses were kept in the mold-contaminated environment for a week after stopping the drug administration.
• The effectiveness of the treatment was assessed by regularly monitoring the concentration of cortisol, a hormone produced by the adrenal gland, in their serum across various timelines (Days 0, 7, 9, 12, 14, 16, 19, and 21).
• Additionally, adrenocorticotropic hormone stimulation testing was conducted on four horses per treatment group on specific days (0, 7, 14, and 21).

Results

• The production of endogenous cortisol was suppressed in the horses treated with beclomethasone and dexamethasone, within just two days of treatment. However, the cortisol production recommenced and matched the levels seen in propellant-treated horses approximately 2 and 4 days after stopping the drug administration.
• The serum cortisol levels in propellant-treated horses gradually reduced during the study and were significantly lower than the baseline on days 14, 16, 19, and 21.
• In terms of ACTH stimulation testing, the rise in serum cortisol concentration post-administration of beclomethasone and dexamethasone wasn’t significantly different from propellant-treated horses.

Conclusions

• The aerosolized administration of beclomethasone and the parental administration of dexamethasone led to a temporary suppression in adrenocortical function. However, the production of endogenous cortisol resumed approximately 2 and 4 days post discontinuation of the treatments.
• The seven-day treatment period did not have any significant impact on the outcomes of the ACTH stimulation testing.