Correlation between cytologic and microbial respiratory profiles and performance in french trotters

International audienceThe impact of clinical and respiratory findings on performance is poorly understood. The aim of this study was to investigate the possible association between cytological, mycological, and bacteriological profiles of the respiratory tract of racehorses and the level of performance. Clinical examination, airway samples (bilateral bronchoalveolar lavage (BAL), tracheal wash (TW) and bilateral guttural pouch lavage (GPL)) and performance results of 32 Standardbred racehorses were analysed. Horses were classified as good performers (GP, n=12) or poor performers (PP, n=20) based on a modified performance-score (out of 4 based on the podiums ratio, earnings and national index and ranking). Data were compared between groups and correlation to performance was statistically analysed by Chi-square, Fisher or Mann-Whitney test depending on variables. Significance was set at P=0.05. The most common respiratory conditions included tracheal inflammation (n=28/32), mild-moderate equine asthma (mEA, n=9/32) and exercise-induced pulmonary haemorrhage (EIPH, n=7/32). While none of the variables or conditions were statistically associated with performance, the following were seen more often in poor performers: tracheal inflammation (GP: 9/12 (75%) vs PP: 19/20 (95%)), positive TW bacterial culture (GP: 2/12 (17%) vs PP 6/20 (30%)) and Mycoplasma (GP: 3/12 (25%) vs PP: 7/20 (35%)). The presence of mEA, EIPH or fungal colonisation of the airways was not associated either with poor performance. The small number of horses limited interpretation. No significant correlation was found between respiratory profiles and performance. However, the higher prevalence of tracheal inflammation, equine asthma and Mycoplasma in poor performers warrants further investigatio