Situations in which she has reared:
1. Lunging: She clearly dislikes being lunged, and will turn into the middle and rear. I work her through it, but she still continues. This is a full on rear, not just spinning in and bringing her feet a few inches off the ground, she goes all the way up.
2. The other day I was leading her out from the field, she has never had a problem with this before, she is a very sweet mare other than this horrible habit. Anyway, as I was leading her out she reared all the way up several times, even striking out once. Now, there was a dog she dislikes running around chasing a bird when this happened, so I am sure that was part of the problem. (Although it is an unacceptable reaction.) BUT, I still need to know how to deal with it for when it happens again, because I'm sure it will.
I understand to fix this problem correctly and safely she will need to go to the trainer, but as I said she is not my horse. I need to know how to handle this situation safely and effectively until I can convince her owner to send her to the trainer or come work with her himself.