Occurrence of exercise-induced pulmonary haemorrhage in show jumping horses

Pulmonary haemorrhage occurs in sport horses performing high-intensity exercise, but the factors involved in the occurrence of pulmonary haemorrhage in jumping horses have not been elucidated. This study aimed to determine the occurrence of pulmonary haemorrhage and factors involved in competitive jumping horses. Fifty adult jumping horses competing in the city of São Paulo, Brazil, were included. The horses were divided into two groups based on jump height at competition: Low group (LG, n=26), with jump height between 1.00 and 1.20m, and High group (HG, n=24), with jump height between 1.30 and 1.50m. Physical examination was performed before and after competition, and airway endoscopy and tracheal wash (TW) were performed 1h after competition. Heart rate (HR; P<0.010), respiratory rate (RR; P<0.010), rectal temperature (RT; P<0.010), and frequency of endoscopic observations of blood in the tracheal lumen (P<0.013) were significantly higher in HG than in LG. TW cytology was not different between the two groups. Incidence of pulmonary haemorrhage was positively correlated with jump height (r²=0.40, P<0.0001), post-exercise HR (r²=0.31, P<0.0001), and post-exercise RR (r²=0.19, P<0.002). In conclusion, pulmonary haemorrhage in jumping horses was associated with the level of performance. Further studies on the pathophysiology of exercise-induced pulmonary haemorrhage in this type of horses are required.