Descriptive analysis of longitudinal endoscopy for exercise-induced pulmonary haemorrhage in Thoroughbred racehorses training and racing at the Hong Kong Jockey Club.

REASONS FOR PERFORMING STUDY: Exercise-induced pulmonary haemorrhage (EIPH) is reported as a performance limiting condition in racehorses, yet few longitudinal studies characterising EIPH have been reported.

OBJECTIVES

To characterise EIPH during training and racing in the absence of prophylactic medication with furosemide among horses imported to Hong Kong during 2007-2012.

STUDY

DESIGN

Retrospective descriptive study of clinical endoscopy, EIPH status, and racing records.

METHODS

Thoroughbred geldings (n = 822) imported from New Zealand between 2007 and 2012 were retrospectively assigned to 4 groups: diagnosed with EIPH via endoscopy (EIPH+), graded using recognised criteria; observed with epistaxis (Epistaxis); free of EIPH on endoscopy (EIPH-); and those in which no endoscopy was performed.

RESULTS

The majority of horses (89%) were subjected to endoscopy once or more (median 15, interquartile range 3-18). Of those undergoing endoscopy, 55% of horses were diagnosed EIPH+ which varied in severity. Few (4%) experienced epistaxis. EIPH+ was diagnosed most frequently (63%) after racing. There was no significant difference in the proportion of EIPH+ and EIPH- horses that raced. Racing career longevity was longest for EIPH+ horses. The number of starts in Hong Kong for EIPH+ horses was not significantly different to EIPH- horses. [Correction added on 9 January 2015, after first online publication: The term 'lifetime starts' has been changed to 'starts in Hong Kong' in the preceding sentence.] Days to retirement were longer for EIPH+ horses. Horses with mild EIPH+ (grade <3) were more likely to be retired for other causes whereas severe grades (≥3) were more likely to be retired for EIPH.

CONCLUSIONS

Exercise-induced pulmonary haemorrhage is common and varies in severity between individuals and between episodes in the same individual. There is no difference in racing career longevity between EIPH+ and EIPH- horses trained and raced without furosemide. See also correspondences by PS Morley and KW Hinchcliff; AD Richards; and S. Preston and C. M. Riggs.