Yesterday, we did some arena work with a friend, then we were going to ride down the road to some trails like we've done many times before. We got about half way down the road, and he stopped and refused to move forward. I kicked, I spanked his butt, I worked him in circles, but going back down the road was not an option. I got off and waked him forward with no problem, when I remounted it was an absolute no way. He was not nervous, or stressed, or excitable - just defiant. We'd back up, he'd go left or right (when it wasn't private property) and he'd walk nicely towards home, but no matter what when I faced his nose down the road it was 4 feet in concrete.
His entire morning routine (i.e. Hay) was screwed up, the Barn Owners are out of town and their daughter who lives with them is in charge. He had not had his hay before we worked (she was a little later) but I made sure he had some breakfast before we started.
I have no idea what to do in this situation. He's normally very sensitive and soft so demanding he do what I asked should have startled him a little...nope. He was like a mule. I have to wonder if there was something in the woods that he knew about and we didn't.
I took him back to the barn, worked him in the arena for another 10 or 15 minutes until we ended up on a positive note and he was listening to me.
In summary, I have two questions:
1. What should I have done in this situation?
2. What possible things would cause this behavior?