Time to resolution of airway inflammation caused by bronchoalveolar lavage in healthy horses.
Authors: Woodrow Jane S, Hopster Klaus, Palmisano Megan, Payette Flavie, Kulp Jeaneen, Stefanovski Darko, Nolen-Walston Rose
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Post-BAL Inflammatory Resolution in Horses Bronchoalveolar lavage remains a cornerstone diagnostic procedure for evaluating equine lower airway disease, yet clinicians have lacked clear guidance on how long procedural trauma induces inflammatory changes that could confound subsequent sampling. Woodrow and colleagues investigated this question in six healthy horses using a randomized crossover design, performing paired lavages at baseline and 48, 72, and 96 hours post-procedure, then analysing cytological populations and inflammatory cytokine concentrations. Whilst neutrophils, eosinophils and mast cells showed no significant changes across timepoints, macrophage percentages increased substantially by 72 hours (45.0%) and remained elevated at 96 hours compared to baseline (37.4%), though interleukin-6 concentrations—a key marker of acute inflammation—peaked at 72 hours before declining. These findings suggest that clinicians may safely repeat BAL procedures at 72 hours or beyond without concern that procedure-induced inflammation will interfere with interpretation, a practically important consideration when serial sampling is clinically indicated for diagnosis or monitoring response to therapy. The persistent macrophage elevation warrants caution if quantifying specific immune subpopulations within that timeframe, though the authors' conclusion that significant inflammation resolves by 72 hours supports this interval as a reasonable minimum between sequential procedures in clinical practice.
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Practical Takeaways
- •Repeat BAL procedures can be safely performed at 72 hours or later without concern for residual inflammation from the previous procedure
- •Single BAL procedures cause transient changes in immune cell populations and cytokine levels that resolve by 72 hours in healthy horses
- •This finding allows clinicians to schedule repeat airway sampling protocols at 72-96 hour intervals when diagnostic follow-up is needed
Key Findings
- •Macrophage percentages were significantly elevated at 72 and 96 hours post-BAL compared to baseline (45.0-45.3% vs 37.4%; P<0.01), but neutrophil and eosinophil percentages showed no significant changes across time points
- •IL-6 concentration increased at 72 hours (5.22 pg/mL) compared to 48 hours (4.38 pg/mL; P<0.001)
- •No significant lung inflammation was detected at 72 and 96 hours post-BAL, indicating safe timing for repeat procedures