Authors: du Preez S, Raidal S L, Doran G S, Nielsen S G, Hughes K J
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Exhaled breath condensate (EBC) analysis offers a non-invasive method for assessing airway inflammation in horses, but its clinical utility depends on reliable, repeatable measurements. Du Preez and colleagues evaluated the consistency of three key biomarkers—hydrogen peroxide (H₂O₂), pH and leukotriene B4 (LTB4)—across multiple collection sessions in healthy horses, whilst identifying environmental and physiological variables that might confound results. Both intra- and inter-day reliability for H₂O₂ and pH proved acceptable (intraclass correlation coefficients ≥0.8), suggesting these markers could serve as diagnostic tools; however, LTB4 measurements were insufficiently consistent for clinical application. Ambient temperature, humidity, time of day and collection location significantly influenced H₂O₂ values, whilst respiratory rate during collection and ambient temperature affected pH—findings that underscore the importance of standardising testing protocols to account for seasonal variation and individual stress responses. For practitioners considering EBC as part of respiratory assessment, particularly in investigations of equine asthma or recurrent airway obstruction, establishing controlled collection conditions and acknowledging these environmental influences will be essential for meaningful interpretation and comparison of serial measurements.
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Practical Takeaways
- •EBC H2O2 and pH could become useful diagnostic tools for equine respiratory assessment, but standardize collection conditions (temperature, time of day, location) to ensure reliable results
- •When using these biomarkers clinically, account for environmental factors—collect samples under consistent ambient conditions and note the horse's respiratory rate during collection
- •LTB4 measurement is not yet reliable enough for clinical use based on poor consistency findings
Key Findings
- •Intra- and inter-day consistency for H2O2 and pH measurements were adequate (ICC ≥0.8), while LTB4 consistency was poor
- •H2O2 levels were significantly influenced by ambient temperature, humidity, time of day, and collection location (P<0.01)
- •pH was influenced by respiratory rate during collection and ambient temperature (P<0.001)
- •EBC H2O2 and pH measurements show sufficient consistency for potential use as diagnostic biomarkers in horses