Discussion

Depecker, M., Richard, E., Pitel, P.H., Fortier, G., Leleu, C., Courouc-Malblanc, A.
Aims: There are limited data concerning the accuracy of cytological diagnosis based on the investigation of either one or both lungs in Standardbred racehorses. The objective of the study was to determine whether either sequential vs. pooled samples or the lung being sampled would significantly influence BALF cytological profiles and subsequent diagnosis in horses. Methods: Sixty-four client-owned Standardbred racehorses in training and actively involved in racing were included in this prospective observational study. BAL was performed using videoendoscopy in both right and left lungs. Comparison was made between cytological analysis of the first syringe, last syringe, and pooled samples collected from both lungs in 8 horses and also between pooled samples from both lungs in 64 horses. Results: Total cell count was significantly higher in the fourth sample compared to pooled and first samples. Lymphocyte percentage was significantly lower in the first sample compared to all others. Macrophage percentage was significantly higher in the first sample compared to the pooled samples. Total cell count and neutrophil percentage were significantly higher, whereas mast cell and lymphocyte percentages were significantly lower in the right compared to the left lung. There was a poor to moderate agreement between left and right lungs when diagnosing IAD and EIPH using BALF cytological evaluation. Conclusions and practical significance: as the lung being sampled significantly influenced whether a diagnosis of IAD and/or EIPH was made, BAL should be performed in both lungs to ensure accurate diagnosis of lower airway disease in horses. Acknowledgements: The authors would like to thank IFCE (National Stud) and SECF (French Trotters Racing Association) for financial support, and also the trainers and the treating veterinarians who have collaborated on this study.