Yesterday, I took him for a walk down the street (just to get him used to the new environment, and in order to get to the trail, we have to walk down this street - it has a 6 foot dirt shoulder) and he reared up because he saw a herd of baby cows in the pasture across the street from him. Now, he's reared before - the first time on the trail, there were dogs running on top of corrugated tin, but it was stupid of me and I'd only had him less than a week and we hadn't done much in the way of ground manners. I wrote it off to that. He reared, and then as soon as we got him moving again, he was perfect for the rest of the walk (oh, I should note that I'm not riding him, I'm leading him - I don't want to be on his back if he rears). Absolutely didn't spook at ANYTHING else - including dogs running along the fence, barking.
The second time he reared was when we were trying to trailer break him, and it was bad. He was striking out at the trailer and actually fell over onto his rump at one point. We finally beat him at that game, got him into the trailer, and the next day we opened the trailer and he walked right in. So, the incident yesterday was the third time.
Is there ANY WAY to make him stop rearing? I'm fairly certain it is a fight response for when he's scared, so how do I get him to look to me as his leader? I know when he's already rearing that the key is to get his feet moving (something difficult to do on a 6 foot dirt shoulder when a pickup truck is coming), so how do I get him to where, instead of rearing as a first reaction, he waits for me to tell him to just walk past the baby cows? HELP PLEASE!!!!!