Barrel racing horses demonstrate a high incidence of nonclinical postrace airway disorders.

Abstract

OBJECTIVE: To describe the prevalence of postrace airway abnormalities in a population of barrel racing horses competing in Oklahoma. METHODS: A descriptive field study was conducted at a single event. Horses underwent resting endoscopy within 60 minutes of competition. Recordings were evaluated and numerical and/or binary scores assigned for pharyngeal lymphoid hyperplasia, recurrent laryngeal neuropathy, dorsal displacement of the soft palate, epiglottic entrapment, and exercise-induced pulmonary hemorrhage. Clients completed a questionnaire detailing the horse's medical history and run time. A linear regression model was used for analysis of pharyngeal lymphoid hyperplasia, recurrent laryngeal neuropathy, and effect of medications on run time. A Poisson regression was used for analysis of combined exercise-induced pulmonary hemorrhage scores. A logistic regression was used for analysis of exercise-induced pulmonary hemorrhage and dorsal displacement of the soft palate binary scores. RESULTS: Airway examinations were evaluated for 106 horses. Abnormalities, including recurrent laryngeal neuropathy, severe pharyngeal lymphoid hyperplasia, and exercise-induced pulmonary hemorrhage, were diagnosed in 83 horses (78.3%). The most common abnormality detected was pharyngeal lymphoid hyperplasia (104 of 106 horses [98.1%]), though only 25 of 104 (24.0%) were severe and included in the 78.3% prevalence. Recurrent laryngeal neuropathy was identified in 65 of 106 horses (61.3%). Presence of pharyngeal lymphoid hyperplasia or recurrent laryngeal neuropathy was not associated with run time. Exercise-induced pulmonary hemorrhage was observed in 30 of 106 horses (28.3%) but had a positive association with run time. Medications did not affect run time. CONCLUSIONS: Mild airway abnormalities were common but not performance limiting in this population of barrel racing horses. CLINICAL RELEVANCE: Subclinical airway abnormalities detectable on endoscopic evaluation may be common in competitive barrel racing horses. Additional studies using dynamic endoscopy are warranted.