There’s a lot floating around in the air in a horse’s environment, and it probably isn’t surprising that it can have a negative effect on his health. At the 2008 American Association of Equine Practitioners Convention, held Dec. 6-10 in San Diego, Calif., Melissa Millerick-May, MS, PhD, assistant professor in the Division of Occupational and Environmental Medicine at Michigan State University, discussed multiple risk factors for airborne particulates in stabling and their association with respiratory problems.

She said the syndrome of inflammatory airway disease (IAD) includes the accumulation of mucus and inflammatory cells in the airways in the absence of clinical signs of disease. In addition to the risks viruses and bacteria pose to the horse, environmental exposure to particulates dispersed from feed, bedding, footing materials, and other sources (such as diesel exhaust) all can lead to IAD. Even small increases in aerodynamic (airborne) small-diameter particles can worsen airway inflammation.

Sizes of particles of concern reported in this study are smaller than can be seen with the naked eye. The largest are comparable to a single grain of pollen, while the smallest particles are smaller than a red blood cell. Degree of exposure to these particles varies with stable and stall location, season, and the degree of activity around the area