99% of the barrel horses I see break down after a few years. It’s sad, but the owners don’t want to wait and would rather cripple their horse than be patient.
Yes, 3.5 is too young to start training barrels. I wouldn’t even introduce what a barrel pattern is (past the walk) until he is at least five years old. Give another 2 years of training slowly, and cross training, before I would compete. That is my ideal training program. Most people aren’t that patient. Are you?
Another problem is that many barrel horses are brain fried. Nothing like screaming at a horse to run as fast as possible–NO WAIT, HALT–GO FASTER, FASTER! Halt again, quicker! Speed up, FASTER! To ruin a good horse.
