Association between equine asthma and fungal elements in the tracheal wash: An environment-matched case-control study.
Authors: Dély Sarah, Gerber Vinzenz, Peters Laureen M, Sage Sophie E
Journal: PloS one
Summary
# Editorial Summary: Equine Asthma and Tracheal Fungal Elements Recent investigations have prompted debate over whether fungi recovered from tracheal wash samples represent a true driver of equine asthma or merely a consequence of disease-related mucociliary dysfunction; this matched case-control study sought to clarify the relationship by controlling for environmental exposure and other relevant confounders. Researchers compared 39 asthmatic horses with 34 controls sourced from the same facilities, performing respiratory scoring, endoscopy, tracheal wash analysis, and bronchoalveolar lavage on all subjects whilst accounting for management factors, tracheal mucus accumulation, and inflammatory markers including multinucleated giant cells (MGCs). The critical finding was that fungal elements in the tracheal wash showed no significant association with asthma status, whereas horses presenting with tracheal mucus scores ≥2 demonstrated 3.6–4.3 times greater odds of being asthmatic—a relationship that held consistently across different MGC counting criteria (≥3 versus ≥10 nuclei). For practitioners, this evidence suggests that whilst tracheal mucus accumulation appears a more reliable indicator of asthma severity, the mere presence of fungi in wash samples should not drive diagnosis or treatment decisions without corroborating clinical and endoscopic findings. The matched design substantially strengthens confidence in these conclusions, as it effectively isolates asthma's effects from confounding environmental and management variables that often complicate interpretation in equine respiratory investigations.
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Practical Takeaways
- •Tracheal mucus accumulation on endoscopy is a reliable indicator of asthma risk and should be actively assessed during respiratory evaluation
- •Presence of fungi in tracheal wash alone should not be used as a diagnostic marker for equine asthma without other clinical findings
- •Environmental matching is important for asthma assessment—shared barn exposure does not explain asthma cases, suggesting individual susceptibility factors are key
Key Findings
- •Horses with tracheal mucus score ≥2 had 3.6-4.3 times higher odds of being asthmatic regardless of multinucleated giant cell definition
- •Fungal elements in tracheal wash were not significantly associated with asthma status despite previous reports suggesting a link
- •Tracheal mucus accumulation was the only variable significantly associated with asthma in the matched barn environment study