Here are photos and a comment from an endurance rider inSouth Africa:

“We managed to complete the Fauresmith National Ride here in South Africa. I used the boots on the last day and the vets were very interested in them. The boots clung on with no problems over extreme terrain.”

Here is more information on the Fauresmith Endurance Ride:

National Equestrian Endurance Race
The town is well known in equestrian circles for the annual National Equestrian Endurance Race, during which the horses and riders must complete a grueling 205km course during the three days of the event. The first endurance ride was held as a consequence of an argument in the magazine “Landbou Weekblad” about which horse breed has the best endurance ability (the Arabian breed emerging victorious).

The Fauresmith International Endurance Ride is considered one of the toughest in the world. It is not the toughest because of the distance, but because riders must complete long distances over three consecutive days. Riders have been known to get up every hour during the freezing nights to check on their horses.