It is possible to corral horses by putting up sheets of fabic that do nothing more than block their view.  They don't challenge the sheet but stay within the confines of the corral of sheets.  It's something I saw on TV once.  They said it was less likely to injure the horses also.  

The Alpha Dog doesn't think like this.  I have a door that doesn't latch.  I thought I could just close it and convince him he couldn't get in.  Before long he flung the door open, as if to say, "What's the meaning of this?!"

Hi Bewell,

Ha!  I didn't know that.   My dog figured out the gate too.  We had to put in a gate that latched on the otherside so he couldn't reach it.  Oh, he's smart, but he uses it for evil!

Bab,

Did you know that elephants are like the corral horses too? If they're used to being tied up, the trainer can attach their rope to anything, even a chair or a skinny branch on a tree and they won't even try to get loose.

Dogs are much smarter than we think. My daughter's Labradore can even un-do the latch of the kiddie gate at the top of her stairs. It took him a little while to figure it out, but now he can do it in a split second. She had to put an actual lock on it.............. BeWell