Endurance horses perform protracted exercise of up to 12 hours for a 50-mile event, and up to 24 hours for a 100-mile competition. Besides metabolic issues created by fluid depletion and electrolyte imbalances due to sweating during sustained performance, immune and respiratory challenges stemming from transport to the event are added concerns. At the 2008 American Association of Equine Practitioners convention, held Dec. 6-10 in San Diego, Calif., this author (Nancy Loving, DVM) presented on unique conditions associated with offering emergency care at endurance events.