The prevalence of abnormal breathing patterns during exercise and associations with dynamic upper respiratory tract obstructions.

Abstract

There is very limited published information on the prevalence and significance of abnormal breathing patterns adopted during canter/gallop. The aim of this study was to report the prevalence of abnormal breathing patterns during canter/gallop and to investigate whether these may be associated with dynamic upper respiratory tract (URT) obstructions. Retrospective analysis of clinical records. Simultaneous audio and URT videoendoscopy recordings from 365 horses referred for treadmill evaluation were analysed. Thirty percent of horses had an abnormal breathing pattern at canter or gallop, of which 23% had a 2:1 breathing pattern (i.e. one breath is taken over two strides). The prevalence of abnormal breathing patterns was higher at low canter speeds than during strenuous exercise. There was a significant association between breathing pattern during strenuous exercise and the presence of an URT obstruction. This study suggests that abnormal breathing patterns during canter and gallop may be associated with dynamic URT obstructions; therefore, horses identified by owners or veterinary surgeons to have an abnormal breathing pattern during exercise, in particular a 2:1 breathing pattern, may warrant investigations for diagnosis of respiratory tract disease.