Endurance riding is a test for both horse and rider. It involves different settings, from the desert to the mountains. The trail has stops where the horses must be checked by a vet. This is to prevent injury. The length of the trail varies. It could be anywhere from four miles to 150 miles depending on the horse and rider experience. The horses are ex rayed and checked by a vet before the race begins. Each horse has a large white number spray painted on the haunch. The reason for this is so when the horses come galloping into the rest stops the steward can record the numbers in the order that they galloped in on. Their is not a limit on the amount of horses that can participate in the event.