I would rather not, but so many things have happened that makes me keep them on. We've got five horses on our farm, two of them are going to be 6 months old this month. The two babies don't have halters on, but all three mares do. My grandparents were nice enough to let me keep my horse there and we've gained a few in the last four years. Well anyway, beings that they are old and can't run around chasing the horses when they get loose we leave the halters on. The fences are really cruddy and if we don't pad lock the gate they get out.

We've had halters on in the pasture for the last 4 years and I've never had any thing bad happen. My horse is blind on one side and regularly looses her halter in the field. I'm not quite sure how they could get severely hurt if they can slip them off She's never slipped it off while tied so it's not like it's a loose halter. The other mares have slipped their halters off as well.

But I would suggest getting proper fitting halters if you're going to leave them on out to pasture. Each one of our three mares uses a different sized halter and we never trade between them.