The consistency and influence of environmental and animal factors on exhaled breath condensate hydrogen peroxide, pH and leukotriene B4 in horses

This study was performed to determine the consistency of exhaled breath condensate (EBC) hydrogen peroxide (H2O2), pH and leukotriene B4 (LTB4) measurements in asymptomatic horses and to define the influence of environmental and animal factors on these variables. Intra- and inter-day consistency for both H2O2 and pH measurements were adequate, with intraclass correlation coefficients ≥0.8, whereas the consistency for LTB4 was poor. H2O2 was influenced by ambient temperature (TA), humidity, time of day and collection location (all P < 0.01), while pH was influenced by respiratory rate during EBC collection and TA (both P < 0.001). The consistency of EBC H2O2 and pH measurements may be sufficient for use as diagnostic biomarkers in horses. However, the influence of identified environmental and animal factors should be considered.