Bronchoalveolar lavage fluid in Standardbred racehorses: influence of unilateral/bilateral profiles and cut-off values on lower airway disease diagnosis.
Authors: Depecker Marianne, Richard Eric A, Pitel Pierre-Hugues, Fortier Guillaume, Leleu Claire, Couroucé-Malblanc Anne
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Bilateral BAL Sampling for Accurate Lower Airway Disease Diagnosis in Racehorses Assessment of lower airway disease in Standardbred racehorses relies heavily on bronchoalveolar lavage (BAL) cytology, yet uncertainty persists about whether sampling a single lung adequately represents the overall pulmonary status. Depecker and colleagues prospectively evaluated 138 French Trotters in active training, performing bilateral BAL via videoendoscopy and comparing cytological profiles between right and left lungs to determine diagnostic concordance. The right lung consistently demonstrated significantly higher neutrophil percentages, haemosiderophage percentages, and haemosiderophage-to-macrophage ratios than the left, with only fair-to-moderate agreement between sides for inflammatory airway disease (IAD) and exercise-induced pulmonary haemorrhage (EIPH) classification. Most concerning was a substantially increased risk of misclassifying affected horses as controls when using restrictive IAD cut-off values on single-lung samples. These findings necessitate bilateral BAL sampling for reliable assessment of lower airway disease in racing Standardbreds, as unilateral sampling risks both false-negative diagnoses and inaccurate evaluation of the degree of pulmonary inflammation—a critical consideration for treatment decisions and performance management.
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Practical Takeaways
- •When performing BAL in racehorses suspected of lower airway disease, sample both lungs rather than one to avoid misdiagnosis; unilateral sampling carries significant risk of false-negative results
- •Be aware that right and left lungs may show different cytological profiles in the same horse—left lung alone may underestimate neutrophil inflammation and EIPH severity
- •Use consistent bilateral sampling protocols for accurate tracking of treatment response and disease progression in horses with suspected IAD or EIPH
Key Findings
- •Neutrophil percentages, haemosiderophage percentages, and haemosiderophage/macrophage ratios were significantly higher in right lung compared to left lung in Standardbred racehorses
- •Fair to moderate agreement was found between right and left lungs for IAD and EIPH diagnosis based on kappa coefficients
- •Sampling only one lung increases the risk of incorrectly classifying horses as controls, particularly when using stricter cut-off values for IAD diagnosis
- •Bilateral BAL sampling is superior to unilateral sampling for accurate assessment of lung cellularity and precise diagnosis of lower airway diseases