Local airborne particulate concentration is associated with visible tracheal mucus in Thoroughbred racehorses.
Authors: Millerick-May M L, Karmaus W, Derksen F J, Berthold B, Holcombe S J, Robinson N E
Journal: Equine veterinary journal
Summary
# Editorial Summary: Airborne Particulates and Tracheal Mucus in Racehorses Visible tracheal mucus accumulation—evident on endoscopic examination—is a recognised marker of poor racing performance in Thoroughbreds, yet the environmental factors driving this condition remain incompletely understood. Millerick-May and colleagues investigated whether stall air quality influences both the presence of tracheal mucus and airway inflammation by measuring particulate matter concentrations three times daily across 107 racehorses housed in three different stables over a three-month period, correlating these measurements with endoscopic mucus scores and tracheal lavage cell counts. The research revealed that two-thirds of horses exhibited visible mucus accumulation, with odds of this condition significantly elevated in enclosed stables and stalls where larger particles (≤10 µm diameter) predominated; notably, smaller particles (≤2.5 µm) showed the strongest association with increased neutrophil counts in tracheal washes, with 68% of samples containing elevated inflammatory cells. These findings underscore that stable design and daily dust management directly influence airway pathology—implications particularly relevant for farriers advising on stable surfaces, nutritionists considering feed dust, and veterinarians counselling owners on performance-limiting respiratory conditions. Practitioners should recognise that particulate exposure is a modifiable risk factor; investment in ventilation, moisture control, and low-dust bedding and forage management may meaningfully reduce tracheal inflammation and its performance consequences.
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Practical Takeaways
- •Optimize stall ventilation and design to minimize dust accumulation—this is a modifiable factor that directly impacts airway health and racing performance
- •Implement dust control management practices throughout the day, particularly focusing on bedding, hay quality, and ventilation to reduce both large and small particulates
- •Regular endoscopic monitoring of tracheal mucus can serve as a practical indicator of stall air quality; excessive mucus suggests need for immediate environmental improvements
Key Findings
- •67% of racehorses studied had visible tracheal mucus accumulations associated with stall air quality
- •Horses in enclosed stables with higher particulate concentrations had significantly increased odds of visible mucus accumulation
- •Larger particles (≤10 μm) were associated with visible tracheal mucus, while smaller particles (≤2.5 μm) correlated with increased neutrophil counts
- •68% of tracheal wash samples contained >20% neutrophils, indicating airway inflammation