IAD in the Sport and Leisure Horse

Most of the evidence that lower (or upper) airway disease is performance limiting has been gained either from experimental studies or from field investigations conducted on racehorses. There is increasing evidence that inflammatory airway disease (IAD) can exacerbate exercise-induced hypoxemia during maximal treadmill exercise and that excessive airway mucus accumulation (MA) can impair racing performance in Standardbred and Thoroughbred racehorses. A large study of racehorses in training showed no association between tracheobronchial secretion (TBS) cytology and performance, but horses that actually raced had higher TBS neutrophil percentages than horses that did not race (Holcombe et al. 2006).
In contrast to the situation in racehorses, little is known about the consequences of upper and lower airway disease on the performance of sport horses (e.g. show-jumpers, dressage, western, endurance and driving horses) and leisure horses. With the exception of eventing horses, sport horses typically do not reach maximal cardiorespiratory effort during competition. Despite the lack of objective data, considerable efforts are undertaken to diagnose these conditions in sport horse practice, especially when the athlete is not performing well. […]