You used to be able to buy a plastic 'bib' type thing which looked like half a bucket (but all rounded edges) and attached to a headcollar. It hung down behind the horses jaw so that if he tried to grab his rug, he would just 'hit' the bib. Doesn't affect eating or drinking at all, but you would want to be sure he couldn't get caught up on anything while out in the field.

In that situation, leather headcollars are better because they will break, whereas nylon ones are extremely strong and can be unbreakable and therefore not so safe.

do you have any idea why he is doing this? and why he would just start doing it recently and never before? its realy frustrating

Could he be bored? Could you put one of the other horses in his paddock so he has a friend. Then perhaps they could scratch withers instead of him munching his rugs? Of course you then have to consider that they could kick each other. Try googling anti-chew equine or horse products. Let us know how you get on! Good luck.

well he has a pony in his field with him and horses either side. I thought he may be bored cuz of the snow with no grazing and not being excerecised but he started it a few weeks ago when he was being ridden everyday and there was no snow.