“What is interesting to understand about the horse is that at rest, it breathes about 86,000 liters of air a day, about 25,000 gallons, which may carry quite a bit of dust particles that can really injure the respiratory tract,” said Laurent Couëtil, DVM, Dipl. ACVIM, of Purdue University in the In Depth: Inflammatory Airway Disease (IAD) session at the 2002 American Association of Equine Practitioners Convention. The result is a chronic cough and mild exercise intolerance, seen in 11-65% of racehorses today, depending on the diagnostic criteria used (endoscopy or cytology) and whether the measurements were taken before or after exercise