Off... definitely. My boy must have had one on forever before I got him as he has a permanent indentation right where the halter lies on his nose.. Since he practically puts it on himself when I go to put it on him, I see no reason to keep one on in the pasture. I think we kept it on for a few days when he moved to a new barn a year ago, just till he knew the drill...
Always off. It's not worth the danger. A horse that is in the same field as mine always has his on. First he had a rope halter left on him- I tried to tell the owner nicely about the dangers, but it was ignored. Theyve had 3 horses since I've been there, all 3 always wear their halters, and at times they've lost the halter but never got hurt, so they have nothing to learn from and think i'm the crazy one. The thing that saddens me the most is all 3 had indentions on their nose where the nose band laid. Their old horse used to be really bad when you'd put pressure on the halter or lead rope- they said it was previously abused. All I could think of was the pain and discomfort that rubbed spot was causing. :(
Another person who agrees with off. My new horse always had his halter on due to being hard to catch and it had rubbed so much hair off his face. Despite being told to leave it on I took it off on the second day and havent left it on since. I figure if you can get close enough to a horse to get hold of a halter then you should be able to get a lead rope around his neck. He walks off as soon as he sees a rope or halter so I just keep the lead rope behind my back and slip it around his neck and lead him back with that. The previous owner did the whole chasing him off as he turned away but my paddocks are too steep for me to chase him for long so I find hiding it works fine. He's probably too set in his ways to change and is perfect in every other way so it doesnt bother me! Fingers crossed the hair grows back
If I JUST bought the horse then for the first few times in the paddock I leave it on, just incase they are escape artists or the new set of eyes sees a flaw in my security system XD
Stalls, halters are always off and normaly in the pasture halters are always off. I would hate for them to get stuck on something, plus searching for halters in the dark is not my favourite game haha, and the way I look at it is if I need a halter to be able to catch my girl I have a serious problem. I try to teach them to come to me when every they see me with the halter in hand so have never had an issue of playing "catch me".
I find the less halter the better, probably feels good to get it off and doesnt leave marks/indents on there faces that way :)
Usually I leave it off unless one of them is injured (Romeo had a bad issue with abscesses when he first came to me) and I will leave it on so that for ANY reason they need help it is already on them. But, if they are injured they are pulled into the paddock and not roaming the pasture.
(Both paddock and pasture have separate entrances and areas in the barn that are available to the horses 24/7)