Comparison between tracheal wash and bronchoalveolar lavage cytology for the assessment of Exercise-Induced Pulmonary Hemorrhage (EIPH) in racehorses

Exercise-Induced Pulmonary Hemorrhage (EIPH) is a common pulmonary disease among racehorses, diagnosed by the detection of blood in the trachea after strenuous exercise or the presence of hemosiderophages in the bronchoalveolar lavage fluid (BALF). Although the latter is considered the most sensitive method to diagnose EIPH, it is perceived as a less practical and more invasive procedure compared to tracheal wash (TW) collection among racehorse trainers. The present retrospective study aimed to verify the agreement between Tracheal wash and BALF cytology in assessing EIPH in racehorses. For this purpose, cytological data from 172 patients regarding hemosiderophage percentage, hemosiderin score, and percentage of recent, intermediate, and old EIPH were reviewed, and the simplified Total Hemosiderin Score (sTHS) was calculated. Non-parametric statistical tests were used to assess the difference and the correlation between TW and BALF. The two cytological methods strongly agreed in evaluating EIPH in racehorses for hemosiderophage percentage (ρ = 0.89, p < 0.001), hemosiderin score (k = 0.63, p < 0.001), sTHS (ρ = 0.87, p < 0.001), percentage of recent EIPH (ρ = 0.95, p < 0.001), intermediate EIPH (ρ = 0.92, p < 0.001), and old EIPH (ρ = 0.85, p < 0.001). In conclusion, TW showed to be a reliable method, which might substitute BALF in assessing EIPH in racehorses.