Bilateral bronchoalveolar lavage cytology profiles in a warmblood horse population during a 1-year period.
Authors: Rasmussen Nanna, Karlsen Pernille, Otten Nina D, Fjeldborg Julie, Hansen Sanni
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Bilateral BAL Cytology in Warmblood Horses Researchers examined whether sampling from a single lung during bronchoalveolar lavage (BAL) provides an accurate reflection of the horse's overall pulmonary cytology profile, comparing individual left and right lung samples against pooled samples across 59 horses in 2021 and 70 in 2022, with 53 horses followed longitudinally across both years. The methodology involved differential cell counts to classify horses as either controls or presenting with airway inflammation (AI), with statistical analysis identifying significant variations between lung sites and sampling approaches. Mast cell counts consistently proved higher in the left lung compared to the right (2021: median 1.6 vs 1.2, P = 0.009; 2022: median 3.1 vs 2.4, P < 0.001), and notably diverged from pooled samples in 2022 (median 2.6, P < 0.001); furthermore, 17 horses changed classification between years from control to AI or vice versa, with pooled samples failing to reliably detect airway inflammation. These findings carry significant implications for diagnostic accuracy, suggesting that clinicians relying on single-lung samples or pooled BAL cytology risk misclassifying subclinical asthmatic cases—a particular concern for performance horses where early detection of airway disease influences management decisions. Practitioners should consider bilateral sampling protocols as more representative of true pulmonary status when BAL cytology informs clinical diagnosis.
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Practical Takeaways
- •Bilateral BAL sampling should be considered over pooled or single-lung samples when assessing horses for airway disease, as one lung may not represent the overall condition
- •Left and right lungs show different cellular profiles (particularly mast cells), requiring standardized sampling protocols for consistent diagnosis
- •Longitudinal monitoring is important as horses can transition between control and inflammatory states; single assessments may miss subclinical changes
Key Findings
- •Mast cell counts were significantly higher in left lung compared to right lung (2021: 1.6 vs 1.2, P=0.009; 2022: 3.1 vs 2.4, P<0.001)
- •Pooled BAL samples were the least reliable for detecting airway inflammation and did not represent overall lung condition
- •17 of 53 horses that were sampled in both years showed changes in BAL cytology classification between control and airway inflammation status
- •Single-lung BAL sampling may not provide representative assessment of bilateral lung pathology