Reducing Your Horse's Exposure to Dust

Researchers have shown that significant amounts of mucus in a racehorse's airway can negatively affect his performance, and they've theorized that dust in the horse's environment contributes to that mucus. Therefore, the logical next step is to reduce dust in a horse's environment in order to optimize his respiratory health. But how do you do that?

To help answer that question, a team of veterinarians led by Michigan State University (MSU) researchers investigated equine exposure to dust in six racehorse stables, with findings presented by Melissa L. Millerick-May, MSc, PhD, assistant professor of medicine at MSU, at the 2009 American Association of Equine Practitioners convention held Dec. 5-9 in Las Vegas, Nev.

"We are investigating equine exposure to particulates (dust particles) less than 10 microns in diameter (invisible to the naked eye,) as particles in this size range are those that are likely to reach further into the horse's lung," she commented.

For the study, 653 horses at a Midwestern Thoroughbred racetrack were evaluated for the presence of mucus in their airways from April through October. From these a subset of horses were selected to be either "cases" (mucus score >2) or "controls" (no visible mucus). Selected horses wore personal breathing zone monitors with the end of the sampling tube placed on the noseband of their halters for roughly 17.5 hours per day. High tracheal mucus scores (2 or greater on a 4-point scale, the level shown to impact racing performance in previous research) were seen in 23.1% of studied horses.

The researchers observed the following:

  • Trainer and month had a significant effect on tracheal mucus scores of 2 or higher.
  • Individual horse behaviors potentially contributing to increased dust exposures (such as stall walking) were not associated with the presence of tracheal mucus.
  • Particulate levels were significantly lower after wet, rainy periods.
  • Particulate levels were highest in the early mornings, when there was the most activity in the barn, and decreased as the day went on and activities ceased and particulates were allowed to "settle out."
  • Barns that were the most open and airy with the least human activity had the lowest particle concentrations.
  • Horses in stalls closest to roads and human offices (high-traffic areas) had the highest particulate concentrations.

Millerick-May recommended the following management practices to reduce dust:

  • Improve ventilation within existing stables, consider appropriate fan placement. Fans placed on the floor re-entrain dust/dirt from the ground back into the air, she explained. Fans should be placed up and off the ground (i.e., mounted to the bars on the front of the stalls with cords well secured to prevent horses from reaching them).
  • Use good-quality, low-dust hay and bedding.
  • Use water as a dust suppressant (i.e., wetting aisles) during periods of dry weather.
  • Keep human activity within the stable at a minimum, such as by minimizing raking or sweeping of aisles.
  • Stable maintenance (i.e., de-cobwebbing) should be done while horses are outside.
  • Vehicles (tractors, four-wheelers, trucks) should be shut off when inside the stable and/or next to doors and windows to prevent exhaust buildup.

"One trainer in the study moved his horses to a more open-air stable, began using water as a dust suppressant, cut down on aisle raking, modified his feeding practices, and said he no longer had a mucus problem," commented Millerick-May. "There have been several success stories like that."

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.