Background: Equine asthma is a chronic disease that negatively impacts welfare and athletic performance. Exposure to respirable dust particles is a major trigger of airway inflammation. A custom-made respirator was developed to reduce inhalation of airborne particulate matter. Hypothesis/
Objectives: We hypothesized that use of a respirator would decrease particulate matter exposure and prevent airway inflammation and pulmonary dysfunction in horses with severe equine asthma (SEA).
Methods: This pilot study used a randomized crossover design. Asthmatic and age-matched healthy horses (n = 8) were randomly assigned to wear the respirator for 2 weeks. Clinical score (CS), pulmonary function testing (PFT), and bronchoalveolar lavage fluid (BALF) cytology were evaluated at baseline, 7 days, and 14 days during each study arm. Respirable dust exposure was measured using an optical particle counter (OPC).
Results: Six horses tolerated the respirator; two SEA horses removed the device. SEA horses with CS > 8 and ΔPmax > 10 cmH₂O returned to remission. CS, ΔPmax, pulmonary resistance (RL), and dynamic compliance (Cdyn) did not significantly differ by treatment over time. Dust particle concentrations were significantly lower inside the respirator compared to outside. Healthy horses had higher BALF neutrophil percentages prior to dust exposure. No significant effect of respirator use was observed in SEA horses. In the second study arm, BALF neutrophil percentages were significantly increased compared to the first arm in both healthy and asthmatic horses. Conclusion and Clinical Importance: The respirator effectively reduces respirable dust exposure and may help limit airway inflammation and asthma exacerbation.
