You would think in this day and age and with the huge money in horseracing and advances in medical technology, they'd be able to ascertain the bone density or whatever it takes to be sure that a horse is actually ready, physically, to race.
There should be mobile scanners that do that sort of thing so these incidents would be at least, far less, if not eliminated.
It's really heartbreaking and I feel sorry for the owners and trainers too; they certainly love their horses, but in the end, it is all about money. Very sad.