Eosinophilic Asthma in Sporthorses

In order to identify typical clinical features of eosinophilic asthma insporthorses a retrospective study was performed in 147 Standard-breds and 123 Warmblood sporthorses diagnosed with IAD. Horseswith a clear positive tracheal wash culture or with RAO were excluded. Horses were subjected to respiratory endoscopy (gradingmucus and blood), tracheal wash and broncheoalveolar lavage (BAL).The prevalence of eosinophilic IAD was higher in the Standardbredpopulation compared to Warmbloods (p=0.001 Chi-square, p=0.002bi-log regression). An increase of eosinophils in the BALF (>1%) of
Standardbreds or Warmbloods was more often associated with a normalcell count of neutrophils in the BALF (p=0.04 Chi-square and p=0.004resp.). Eosinophilic IAD was more prevalent in Warmblood horses<5 years (p= 0.01 Chi-square) compared to >5years. In the Standardbredpopulation there was no age difference. Increase of eosinophils was, incontrast to neutrophils, not associated with cough nor increased mucusscore. This study suggests eosinophilic IAD may be exercise relatedcomparable to nonallergic eosinophilic asthma in humans1.Thisisinaccordance with Hare2suggesting eosinophilic IAD in racehorses is ofnon-allergic origin and associated with racing and airway hyper-responsiveness. A follow-up study in which Standardbreds that do notrace are compared to racing Standardbreds might clarify this hypothesis.
KeywordsNon-allergic eosinophilic asthma
References:1. Helenius I, Haahtela T. Allergy and asthma in elite summer sportathletes.J Allergy Clin Immunol. 2000;106(3):444-4522. Hare JE, Viel L. Pulmonary eosinophilia associated with increasedairway responsiveness in young racing horses.J Vet Intern Med.1998;12(3):163-170