According to recent study results, if an athletic horse is constantly exposed to microscopic airborne particles then he could experience enough inflammation and mucus to decrease his performance abilities, even if he doesn’t exhibit any outward signs of respiratory distress.

"Poor air quality could contribute to the accumulation of tracheal mucus, which is known to be associated with poor performance in racehorses," explained Melissa Millerick-May, PhD, assistant professor of medicine at Michigan State University’s College of Human Medicine.

In a previous study, Millerick-May and colleagues found that horses are often exposed to airborne particulates (i.e., from feed, bedding, and footing) when stabled and that these particles can reach the lower lung, potentially inducing lower airway inflammation.

"Although it seems implicit, there are a limited number of studies that have intimately looked at the relationship between the concentration and size distribution of small-diameter particulates and the presence of tracheal mucus and inflammatory cells in racehorses," said Millerick-May.

To better establish this relationship, Millerick-May and colleagues measured airborne particulate matter from three Thoroughbred racetrack stables in July, September, and November, at three different times each test day. They also examined 107 apparently healthy racehorses endoscopically to assign a "mucus score" and collected a tracheal lavage fluid sample from each animal.

Key findings were:

Sixty-seven percent of horses had tracheal mucu