Exhaled breath condensate hydrogen peroxide and pH for the assessment of lower airway inflammation in the horse

Measurement of hydrogen peroxide (H2O2) concentration and pH in exhaled breath condensate (EBC) is useful for detection and monitoring of asthma in humans. In contrast, limited information on the use of these parameters for the investigation of lower airway inflammation (LAI) is available for horses. Aims of the current study were to investigate the intra- and inter-day variations of EBC H2O2 concentration and pH in horses and establish any relationship(s) with LAI. Both intra- and inter-day variability of EBC H2O2 concentration were large, while those of pH were small. No significant difference in the intra-day or inter-day H2O2 concentrations or pH measurements were found in control or LAI horses, except for inter-day H2O2 concentration in horses with LAI (p = 0.019). There was no significant difference in EBC pH or H2O2 concentration between control and LAI horses, however a trend for a reduced pH in horses with LAI was observed.