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

## TL;DR

This study tests a new device for collecting exhaled breath condensate from horses and finds that pH and hydrogen peroxide levels remain stable over time.

## Contribution

A novel horse-specific device for EBC collection is evaluated for feasibility and variability in pH and H2O2 levels.

## Key findings

- EBC pH and H2O2 levels showed no significant intra- or interday variation.
- No correlations were found between EBC parameters and BAL or TW cytology.
- About one-third of samples were insufficient for analysis due to low volume.

## Abstract

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.