Effects of an external nasal strip and frusemide on pulmonary haemorrhage in Thoroughbreds following high-intensity exercise

The purpose of this study was to examine the effects of an external nasal s trip (NS), frusemide (FR) and a combination of the 2 treatments (NS + FR) o n exercise-induced pulmonary haemorrhage (EIPH) in Thoroughbred horses. It was hypothesised that both the NS and FR would attenuate EIPH as assessed b y red blood cell count in bronchoalveolar lavage fluid. In random order, 8 horses completed each of 4 sprint exercise tests on a treadmill: 1) NS; 2) FR (0.5 mg/kg bwt i.v., 4 h pre-exercise); 3) NS + FR; and 4) control (C; n o treatment). After a 5 min warm-up (4.5 m/s), horses completed 2 min runni ng at 120% maximum oxygen consumption ((V) over dot (O2max)) with the tread mill set at 3 degrees incline. Mean +/- s.d. running speed was 14.2 +/- 0.2 m/s. In the FR and NS + FR trials, horses carried weight equal to that los t as a result of frusemide administration. During exercise at 120% (V) over dot (O2max), oxygen consumption ((V) over dot (O2)) and carbon dioxide pro duction ((V) over dot (CO2)) were measured at 15 s intervals. Plasma lactat e concentration was measured in samples collected before exercise, at the e nd of the sprint and after 5 min cool-down at the trot. Thirty minutes afte r the run, bronchoalveolar lavage (BAL) was performed and the red cell coun t in the fluid quantified. (V) over dot (O2) and (V) over dot (CO2) were si gnificantly lower in NS and NS + FR trials than in the C and FR trials at t he end of the sprint exercise protocol. However, plasma lactate concentrati ons did not differ among treatments. Compared with the C trial (61.1 +/- 30 .5 x 10(6) red blood cells/ml BAL fluid), pulmonary haemorrhage was signifi cantly (P <0.05) decreased in both the NS (15.9 +/- 4.0 x 10(6) RBC/ml) and FR (12.2 +/- 5.8 X 10(6) RBC/ml) trials. EIPH in the NS + FR trial (7.9 +/ - 1.0 X 10(6) RBC/ml) was further diminished (P <0.05) compared to the NS t rial, but not different from the FR trial. We conclude that both the extern al nasal strip and frusemide attenuate pulmonary haemorrhage in Thoroughbre d horses during high-speed sprint exercise. The external nasal strip appear s to lower the metabolic cost of supramaximal exertion in horses. Given the purported ergogenic effects of frusemide, the external nasal strip is a va luable alternative for the attenuation of EIPH.