Background: Low testosterone levels are associated with poor lung function in human asthmatics, and conversely, androgen administration improves airway obstruction in asthmatic women. Hypothesis: Androgens improve lung function in horses with severe asthma (SEA). Animals: Ten horses with SEA from a research herd.
Methods: The effects of oral dexamethasone (0.06 mg/kg, q24h, 10 days) and intramuscular testosterone cypionate (single dose, 0.35 mg/kg) were compared in a randomized, blinded cross-over study (two weeks washout). Lung function was assessed by standard lung mechanics at baseline (Day (D) 0), D5, and D10. The cytology of bronchoalveolar lavage was evaluated at baseline and D10. Data was analyzed using mixed linear models.
Results: The lung function improved over time (p < 0.001) with no difference between groups. There was a significant interaction between the treatment group and time as dexamethasone produced a larger reduction of resistance (p < 0.001; median (IQR) of 2.8 cm H2O/L/s (2.1-3.5) at D0 and 0.6 (0.5-0.8) at D10 for dexamethasone, and of 2.5 (2.1-3.1) at D0 and 2.3 (1.4-3.1) at D10 for testosterone) and elastance (p < 0.04; 5.1 cm H2O/L (3.1-5.6) at D0 and 0.5 (0.4-0.8) at D10 for dexamethasone, and 4.5 (1.7-6.8) at D0 and 3.0 (1.2-3.7) at D10 for testosterone). Neither dexamethasone nor testosterone modified airway neutrophilia. The treatment order had no impact on measured parameters. Conclusions and clinical importance: Testosterone was not as effective as dexamethasone in relieving airway obstruction in SEA, but the mechanisms leading to lung function improvement with androgens require further investigation.
