Hi there! I'm new here, but I've had some issues in the past
that are similar to your experience with Dozer, maybe it can help you.
All I feel is going on here, is Dozer is completely testing you, and winning from what you've said. Sure, he could be
missing his pony friend, but you need to work this out of him so he's safe again. When he acted up on
the hill the first time, and you finally broke down and had your father come and pick you up, Dozer won. Now he
has found a way to get out of working. Most horses would love to never do any chores - what a life, huh?
When he begins to get spooky, you need to work him right there.
Circle him in a trot if you have the room, until he begins to calm. Every
single time he does it, you need to react positively and calmly. You
need to take control of his actions and show him. It may take some
doing, because of that very first time that he won the battle on the hill. Believe me, these guys remember.
I had a quarter horse years ago that I boarded, and the owner
before me was a weekend warrior city police officer that could
not ride, and when the horse reared, he got scared and got off
and put him away. Yeah, then I got him. Took me FOREVER to
show him that I wasn't giving up. It took me awhile, but I did
manage to semi-cure him of it, but it was always right under the surface.
So it may take awhile, but with some work on both your parts,
you may be able to get him back to being safe. I don't think he
looks thin in the picture with the pony at all, he just looks like a
narrow chested horse. The first picture his hips are not quite as
rounded, but he does not look malnourished to me.
Good luck with him.