lots of animals get high off of their own kinds of drugs...
i mean a lot of cats loooove catnip which is a drug. horses will sometimes chew on wood and inhale which is called "cribbing" and that gets them high. researchers have inserted electrodes into rats' brains which gave them a euphoric high when activated, and the rats would keep pressing the lever to activate them until they passed out. i don't think it's right to hold an animal down (or person, for that matter) and force them to take a drug, but i'm assuming if they didn't want smoke in their faces, they'd just leave the room.
just my opinion though, i don't mean to disrespect anyone.