Fig. 1

a Clinical score and b tracheal mucus score, before and after the initiation of each challenge. sEA, severe equine asthma; CTL, control; d-2, 2 days before challenge; d + 5, 5 days after challenge. *, ** significant difference between groups (P < 0.05 and < 0.01), based on ANOVA investigation. Significant overall interactions (P < 0.05) were also found between ‘challenge’ (steamed, dry) and ‘time’ (d-2, d + 5); the p-value correspond to the subsequent Tukey-Kramer’s post-hoc test