Intraday and Interday Evaluation of pH and Hydrogen Peroxide in the Exhaled Breath Condensate of Horses Using A Portable Device.

The analysis of equine exhaled breath condensate (EBC) lacks standardized methodology, and current collection devices are often adapted for research. This study evaluates a novel horse-specific EBC collector and assesses the variability of EBC pH and hydrogen peroxide (H2O2) levels, exploring potential correlations with bronchoalveolar lavage (BAL) and tracheal wash (TW) cytology. Eleven healthy mixed-breed mares from a teaching herd, with no evidence of airway abnormalities, were included in this randomized observational study. The collection efficiency of the proposed device was assessed, and intra- and interday variations in EBC pH and H2O2 levels were analyzed. Airway endoscopy, tracheal mucus scoring, and TW and BAL fluid cytology were also performed. EBC pH showed no significant intra- (P = 0.631, ES 0.008-0.456) or interday (P = 0.864, ES 0.116-0.365) variation, nor did H2O2 levels (P = 0.953, ES 0.077-0.185; P = 0.929, ES 0.019-0.190, respectively). In this study, no correlations were found between EBC parameters and BAL or TW cytology. However, 34.5% of pH samples and 32.7% of H2O2 samples were insufficient for analysis due to low sample volume. These findings suggest that EBC collection using the horse-specific device is feasible and that pH and H2O2 levels remain stable regardless of collection time. However, further refinement of the device is necessary to improve sample yield and ensure reliable analysis.