Chronic airway inflammation in the horse: The role of environmental exposure

Kathleen Marie Ivester, Purdue University

Abstract

Inhalant exposure to airborne irritants commonly encountered in horse stables is implicated in the pathogenesis of inflammatory airway disease (IAD) and recurrent airway obstruction (RAO), two common inflammatory, non-infectious diseases of the equine airway. These diseases pose significant risks to the performance, health, and welfare of horses across all equine disciplines, but little is known about the interaction between the pulmonary immune system and inhaled environmental irritants presumed to trigger disease development. This study examined the IAD status and cytologic phenotype of young Thoroughbreds entering race training while characterizing the relationship between bronchoalveolar lavage fluid (BALF) cytology and exposure to dust, endotoxin, and ammonia and establishing a proteomic method to identify inhalable barn dust aeroallergens. During a natural exposure trial, Thoroughbreds were followed over the course of their first month in training. BAL was performed at enrollment and at 14 and 28 days in training. Environmental samples were collected weekly at the breathing zone, and exposure to inhalable dust, respirable dust, endotoxin, and ammonia were determined. Results indicate that breathing zone measures of exposure are necessary to capture the effects of method of feeding and individual horse behavior. BALF eosinophils were found to correlate with respirable dust, providing the first epidemiologic evidence that eosinophilic IAD arises from hypersensitivity to inhaled particulate antigens. Elution of protein from inhalable dust, followed by immunoblot and proteomic analysis proved feasible and allowed identification airborne antigens that may prove important in the pathogenesis of IAD and RAO.

Degree

Ph.D.

Advisors

Couetil, Purdue University.

Subject Area

Animal Diseases|Veterinary services

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