This happens very little, but I can actually speak from experience here....
BAD IDEA!!!
We did this at my high school during my sophomore year. Toto had MASSIVE stage-fright (and during rehearsal even ended up peeing on the
stage... and for some reason a tech had to clean it up, instead of the dog's owner). He always wanted to run off into the wings. And whenever he had to come on from the wings, he had to be dragged on. If he hadn't had a leash, we pretty much wouldn't have had a Toto.
Not being a major character, I really don't think it's totally worth it. But this is just my opinion. The purpose of
theatre is for people to get totally lost in the show they're watching to the
point that they forget it's not real life. When Toto is frightened, trying to
escape Dorothy and running off
stage, it kinda ruins the
effect. Not to say that using a stuffed dog is much better, to be honest...
If you do use a real dog, I would suggest one that is well-trained in
stage performances. I once saw a story on the news about this woman who trained Totos specifically for the musical, teaching them commands they would use on
stage. I even think getting into the
basket was one.
I guess my
point is, don't use just any dog for Toto. Get one that has
stage experience and won't freak out when it sees a big audience
on opening night that wasn't there during final dress.