Case-Control Study of Risk Factors for Equine Asthma in Texas

Abstract Equine asthma is a common condition in horses, for which few host-related risk factors have been identified. The objective of this study was to identify host-related risk factors for the development of equine asthma. A retrospective, case-control study was performed, utilizing horses presented to the Texas A&M University, Veterinary Medical Teaching Hospital from January 2014- December 2018. Incident cases of mild to severe equine asthma (n=37), diagnosed clinically with cytologic support of disease were examined. For each case, two control populations were identified, including one temporal control (n=37) and one age-matched control (n=37). Data collected included signalment, dietary and stable management, prior medical history, metabolic status, physical examination findings, and results of cytologic evaluation via bronchoalvelolar lavage or tracheal wash. Conditional logistic regression was used to compare data on equine asthma cases with data from each set of controls. Results indicated that obesity (Body Condition Score ≥ 7) was the only statistically significant risk factor for equine asthma in this population of horses. These results may aid in identification of targets for management, prevention, and further investigation into the pathogenesis of equine asthma. Early identification and intervention of horses at risk of lower airway disease could ameliorate the impact of disease.