Progression of dynamic obstructions of the upper respiratory tract in 135 Thoroughbreds during exercise as cause of poor performance

Progression of dynamic obstructions of the upper respiratory tract in 135 Thoroughbreds during exercise as cause of poor performance

Entwicklung dynamischer Obstruktionen der oberen Atemwege bei 135 Vollblütern während des Trainings als Ursache für Leistungsschwäche

Oellers S, Barton A K, Ohnesorge B

DOI: 10.21836/PEM20200305
Year: 2020
Volume: 36
Issue: 3
Pages: 227–237

The progression of dynamic obstructions of the upper respiratory tract in Thoroughbreds was examined by performing on-board exercise endoscopy during fast work on 135 horses. Exercise endoscopy was performed on horses with and without abnormal respiratory noise and with and without a history of poor performance. For classification, the exercise was divided into three equal sections. 54.8 % (74 horses) of the 135 horses examined had a history of poor performance; only 1.5 % at the beginning of fast work and 35.5 % at maximum performance. At the beginning of fast work, abnormal respiratory noise was audible in 8 horses (5.9 %), shortly before the end of training in 55 horses (40.7 %). A marked increase in the number of affected horses of each dysfunction among the horses with obstructions in the area of the upper respiratory tract could be observed with increasing performance. Some obstructions only occurred during higher performance levels. It could be demonstrated in which phase during horses’ training obstructions occurred with or without having effect on the performance. The assessment of ACC showed which grade of ACC causes a negative impact on horses’ performance in the different stages of exercise. As there is a high probability of poor performance at least during races with ACC of grade B3 or higher, treatment options can already be discussed here. As DDSP mainly occurs during maximum performance, it can only be definitely excluded if the horse is exercised to maximum performance during endoscopy. The evaluation method used in this study allows a better analysis of the effect of dysfunctions on each horse’s performance, even if multiple obstructions occur