Endoscopic findings, microbiological and cytological evaluation of tracheal aspirates in a population of Standardbred horses with poor performances
Sixty-two Standardbred horses housed at the same racetrack, with history of reduced exercise tolerance, cough lasting for at least two weeks and/or prolonged recovery time were clinically examined. An endoscopic examination of the nasopharynx, larynx and trachea to the level of the carina was performed, amount of mucus in trachea was registered and samples of tracheal wash for cytological and microbiological examinations was collected. A strong statistical association between amount of mucus in trachea and neutrophils percentage in tracheal wash was found. Bacteria isolated included <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> (14 horses), <i>Streptococcus pneumoniae</i> (four horses), <i>S. mutans</i> (four horses), <i>S. equinus</i> (four horses) and <i>Burkholderia cepacia</i> (10 horses). <i>S. zooepidemicus</i> and <i>S. pneumoniae</i> were associated with elevated amount of mucus and increased neutrophilic percentage. <i>B. cepacia</i> was associated with cytological evidence of haemosiderophages but its role in racehorses needs further investigations. <i>Mycoplasma</i> spp. and <i>Pasteurella</i> spp. have not been isolated, suggesting that, as for the other putative causes of inflammatory airway diseases, infection could have a regional distribution among horse populations. This study shows that various types of airway inflammations exist in the examined population and that <i>S. zooepidemicus</i> and <i>S. pneumoniae</i> could play an important role in etiopathogenesis of airway inflammation in some horses. Particulate matter, pro-inflammatory agents or noxious gases present in the stables or on the track matter, could be the cause of inflammation in non infected horses.