From the Ontario Competitive Trail riding Association Website - an interesting article, explaining about dehydration and re-balance of electrolytes. The attached spreadsheet gives guidelines for performing vet gate checks.
Endurance GB The Competitive Long Distance Horse Riding Society for England and Wales National Agricultural Centre, Stoneleigh Park, Kenilworth, Warwickshire CV8 2RP telephone: 02476 697929
Endurance GB The Competitive Long Distance Horse Riding Society for England and Wales
"Our mission is to promote and enhance the sport of Endurance (Competitive Long Distance) Riding within the United Kingdom, by providing competition, training and development opportunities that will appeal to all levels of rider from beginner to world class winner."