Efficacy of nasal strip and furosemide in mitigating EIPH in Thoroughbred horses

The purpose of this investigation was to study the effects of an equine nasal strip (NS), furosemide (Fur), and a combination of both (NS + Fur) on exercise-induced pulmonary hemorrhage (EIPH) at speeds corresponding to near-maximal effort. Five Thoroughbreds (526 +/- 25 kg) were run on a flat treadmill from 7 to 14 m/s in 1 m.s(-1).min(-1) increments every 2 wk (treatment order randomized) under control (Con), Fur (1 mg/kg iv 4 h prior), NS, or NS + Fur conditions. During each run, pulmonary arterial (Ppa) and esophageal (Pes) pressures were measured. Severity of EIPH was quantified via bronchoalveolar lavage (BAL) 30 min postrun. Furosemide (Fur and NS + Fur trials) reduced peak Ppa similar to7 mmHg compared with Con (P<0.05) whereas NS had no effect (P>0.05). Maximal Pes swings were not different among groups (P>0.05). NS significantly diminished EIPH compared with the Con trial [Con, 55.0 +/- 36.2; NS, 30.8 +/- 21.8x10(6) red blood cells (RBC)/ml BAL fluid; P<0.05]. Fur reduced EIPH to a greater extent than NS (5.2<plus/minus>3.0x10(6) RBC/ml BAL; P<0.05 vs. Con and NS) with no additional benefit from NS + Fur (8.5<plus/minus>4.2x10(6) RBC/ml BAL; P>0.05 vs. Fur, P<0.05 vs. Con and NS). In conclusion, although both modalities (NS and Fur) were successful in mitigating EIPH, neither abolished EIPH fully as evaluated via BAL. Fur was more effective than NS in constraining the severity of EIPH. The simultaneous use of both interventions appears to offer no further gain with respect to reducing EIPH.