Has anyone tried these before? When I took Bentley in for his yearly check up last week, she told me I should look into getting one for him. She seems to think it would really help him to relax and not to be so stressed out over everything. This isn't in place of training - because were going to start him up again, but just curious if anyone has any stories with it. People don't leave them on when they are alone, do they? I'd be afraid he'd get stuck on something in his crate, chew it off, etc?