Airborne particulates (PM10) and tracheal mucus: A case–control study at an American Thoroughbred racetrack.

ML Millerick-May, W Karmaus, FJ Derksen, B Berthold and NE Robinson

Personal monitors which detected the particle concentrations in horses’ breathing zones were used to determine if there was an association between an individual’s exposure to airborne particles and tracheal mucus accumulation. The benefits of using personal monitors rather than fixed environmental monitors are that the particles dispersed as a result of the horse’s activity will be reflected in the breathing zone, but may not be increased in the region of the monitor. A total of 53 cases and 60 controls were used in the study, with controls matched on the presence or absence of clinically significant tracheal mucus. Endoscopic examination and tracheal lavage was performed and each horse also had an average of 17.5 hours of recording time of breathing zone particle concentration. Airborne particle exposure was found to be significantly higher in cases compared with controls. The absolute neutrophil counts from tracheal lavage fluid were significantly higher in cases compared with controls. The neutrophil count was found to be significantly associated with the concentration of air particles.

The bottom line: Tracheal mucus is significantly associated with the airborne particulates within an individual horse’s breathing zone, therefore efforts to reduce tracheal mucus should focus on an individual’s particle exposure.

Photo: Equine Veterinary Journal 15 AUG 2014 DOI: 10.1111/evj.12303


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