'Map' Airborne Particles in Barns to Minimize Airway Disease

Airway disease is a well-known cause of poor performance in athletic horses, and although many owners and trainers attempt to minimize the dispersion and inhalation of airborne particles, lots equine athletes still develop airway disease. According to a recent study, a new technique called "particle mapping" could help identify when and where harmful airborne particles are likely to remain suspended and help owners and trainers devise ways to minimize equine (and human) exposures to these particles.

Particles less than 10 microns in diameter have the potential to reach the horse's lower airways (lungs and bronchi) and are associated with indices of airway inflammation. Particles this size are often found in stables and typically originate from hay, bedding, footing or flooring materials, road dust, and tractor or vehicle emissions.

"Because these particles are smaller than what can be viewed with the naked eye, it's therefore easy to think that because you don't see a cloud of dust, the particles aren't there," said lead author Melissa Millerick-May, PhD, assistant professor of medicine at Michigan State University's College of Human Medicine. "It's these small particles that you don't see that reach the lower airways and potentially cause irritation/inflammation."

To increase owners' understanding of how barn design and temporal and seasonal factors impact air quality, Millerick-May used commercially available real-time particle monitors in three architecturally different barns at various times of the day and during three different seasons at Thistledown Racetrack in Cleveland, Ohio. In total, 717 measurements were taken during the study period.

Key findings included:

  • Particle concentrations were highest during the month with the least rainfall (September), and lowest during the wet/humid month (July). Interestingly, there was not a significant decline in particle concentration during November when the weather was cold and wet/snowing (likely because all the stables had the doors/windows closed tightly, virtually eliminating all sources of natural dilution ventilation);
  • Particle concentrations were highest in the morning than any other time of day, likely as a consequence of human activity (i.e., feeding, cleaning, grooming);
  • Completely enclosed barns with little natural ventilation had significantly higher particle concentrations than open-sided stables; and
  • Within a single stable, some stalls had consistently higher particle concentrations than others, potentially putting these horses at higher risk of airway inflammation.

"How barns are managed also influenced particle concentrations," noted Millerick-May. "For example, busy stables with multiple stalls being cleaned at the same time, horses being groomed and walked, hay nets packed in or near the stalls, and aisles being raked all lead to simultaneous particle dispersion. The utilization of 'wet methods' (i.e., dampening dusty substances) during cleaning/feeding should help reduce particle dispersion, in-turn reducing exposures."

She also suggested turning off vehicles or tractors adjacent to (or within) stables rather than letting them idle to reduce exposures to ultrafine particles from vehicle exhaust.

Millerick-May concluded, "Particle mapping can help identify horses 'at risk' for inhaling microscopic particles that are believed to contribute to airway inflammation, and can help identify management strategies to minimize the dispersion of these particles."

The study, "Particle mapping in stables at an American Thoroughbred racetrack," will be published in the September 2011 edition of the Equine Veterinary Journal. The abstract is available on PubMed.

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