The efficacy of N‐acetylcysteine in decreasing airway inflammation and mucus accumulation in horses with 18 hours of head confinement

Abstract Background During transportation many horses develop post‐transportation infection, which can be life‐threatening and end their sport career. Preventing mucus accumulation and inflammation during transportation is vital, emphasizing the need for effective strategies to enhance overall horse health welfare. Objectives Assess the impact of N‐acetylcysteine (NAC) on mucus accumulation and inflammation in horses subjected to 18 hours of head confinement. Animals Six healthy crossbred horses, 5.3 ± 2.1 years of age and weighing 387 ± 30 kg. Methods Prospective placebo‐controlled cross‐over design study. The horses' heads were restrained in their stalls for a period of 18 hours. They were studied under 4 conditions: Not confined (NC): before head confinement, placebo (P), and confined head (CH): 18 hours of head confinement without treatment, and N‐Acetylcysteine (NAC): 18 hours of head confinement treated with NAC before confinement (15 mg/kg/day NAC PO for 3 days). Bronchoalveolar lavage (BAL) was performed in each condition. Mucus accumulation along the trachea was evaluated by endoscopy. Results Endoscopic scores were significantly different between CH and other conditions, whereas no significant differences were found among NC, P, and NAC. The BAL cell count (34 291 ± 2624 cells/μL), neutrophil and lymphocyte count (18 601 ± 3193 cells/μL and 3337.4 ± 593 cells/μL, respectively) in CH were significantly higher compared to NAC. Neutrophil percentage was significantly higher in CH (53.8 ± 8%) compared to horses that received NAC (20.08 ± 8%). Conversely, in comparison to NAC (66.33 ± 9%), the percentage of macrophages was significantly lower in CH (35.7 ± 10%). Conclusions N‐acetylcysteine was found to significantly decrease mucus accumulation and inflammatory cell counts in horses with head confinement.