YCBM I can assure you it is true, and that is a huge part of the problem. In the 40 k qualifier 2 horses had catastrophic injuries, these horses were very unlikely to be overtrained, or be carrying many injuries as they are young horses just starting, the number of starters in that race was...
Before the fairly recent trends in Arabia, endurance was a safe sport with very few fatalities. Huge numbers of starters, and unskilled rides, coupled with the training, and veterinary intervention needed to get a horse to run the speeds now achieved over there all contribute to the sudden...
I along with everyone else am amazed that you would even contact a saddler on a sunday, let alone expect a reply. If your horse is sore you should not even think of riding him for a while. Lead him out, lunge, loose school, but do not sit on his sore back until the soreness has gone away.