Respiratory oscillometry testing in relation to exercise in healthy and asthmatic Thoroughbreds

Background Racehorses may experience exercise‐induced bronchodilation or bronchoconstriction, with potential differences between healthy and asthmatic individuals. Objectives To identify exercise‐related lung function variations by oscillometry in racehorses, compare lung function between healthy and mild equine asthma (MEA) horses, assess oscillometry's potential as a predictor of racing fitness. Study design Prospective case–control clinical study. Methods Fourteen Thoroughbred racehorses (5 healthy, 9 MEA) underwent a protocol including respiratory oscillometry at rest, exercise with fitness monitoring, oscillometry at 15 and 45 min post‐exercise, and bronchoalveolar lavage fluid (BALf) cytology. Oscillometry parameters (resistance [Rrs] and reactance [Xrs]) were compared within and between healthy and MEA groups at different timepoints. Associations between Rrs and Xrs at rest and 15 min post‐exercise and BALf cytology and fitness indices were evaluated. Results MEA horses showed higher Rrs at 15 min post‐exercise (0.6 ± 0.2 cmH2O/L/s) than healthy horses (0.3 ± 0.1 cmH2O/L/s) (p