 Concentrated equine serum reduced EIPH by 53% through a combined mechanism of a 30% reduction in inflammation and an increased functionality of the WBCs.Other anti-inflammatory agents, such as hesperidin-citrus bioflavinoids, vitamin C, NSAIDs such as phenylbutazone, corticosteroids, heated water vapor therapy, cromoglicic acid or nedocromil, have no beneficial effects in reducing EIPH severity.Phenylbutazone can partially reverse the beneficial effects of furosemide.