Comparison of Tracheal Wash and Bronchoalveolar Lavage Cytology in 154 Horses With and Without Respiratory Signs in a Referral Hospital Over 2009-2015.
Authors: Rossi Heini, Virtala Anna-Maija, Raekallio Marja, Rahkonen Emmi, Rajamäki Minna M, Mykkänen Anna
Journal: Frontiers in veterinary science
Summary
# Editorial Summary Distinguishing clinically significant airway inflammation from normal variation remains challenging in equine respiratory diagnostics, and this retrospective analysis of 154 horses examined whether tracheal wash (TW) or bronchoalveolar lavage (BAL) cytology offers superior diagnostic accuracy. Researchers compared neutrophil percentages obtained from both sampling methods at rest, stratifying horses by clinical respiratory signs and endoscopic findings, then applied receiver operating characteristic curves and Bayesian latent class modelling to determine optimal diagnostic thresholds and calculate sensitivity and specificity for each technique. Tracheal wash demonstrated higher sensitivity and specificity overall, with ROC analysis suggesting revised cutoff values of 17.7% for TW and 7% for BALF, though the authors concluded the conventional thresholds of >20% and >5% respectively remain clinically appropriate. Only 17.5% of horses were classified differently between the two methods, indicating substantial agreement despite TW's superior discriminatory ability. For practitioners, these findings support TW as the preferred sampling method when diagnostic accuracy is paramount, though the authors emphasise that further investigation across different horse populations and cell types is needed before definitively recommending single sampling protocols for all clinical scenarios.
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Practical Takeaways
- •Tracheal wash is a more reliable diagnostic method than bronchoalveolar lavage for detecting airway inflammation in your patient population, with superior sensitivity and specificity
- •Current clinical cutoff values (>20% neutrophils for TW, >5% for BAL) remain appropriate for diagnosing airway inflammation despite slightly different optimal ROC thresholds
- •The two sampling methods show good agreement overall, so choice may depend on clinical feasibility, but TW appears preferable if airway inflammation diagnosis is your primary goal
Key Findings
- •Tracheal wash showed higher sensitivity and specificity than bronchoalveolar lavage for detecting airway inflammation (ROC analysis)
- •Only 17.5% of horses were classified differently between the two sampling methods, indicating substantial agreement
- •Neutrophil percentage correlated between tracheal wash and BALF samples
- •Optimal cutoff values of 17.7% for tracheal wash and 7% for BALF were identified by ROC curves, though current clinical cutoffs of 20% and 5% remain appropriate