use hoof oil and put it on the insides of their feet works well for a while but if its for more than a few hours cant imagine there will be something that lasts
Get some plasticine (or whatever they call it theses days) and warm it up a little - pack it into the hoof (but not over the frog) walk the horse on a firm level surface while it cools down, and then the horse is ready to turn out. Take it out when the horse comes in, but if it does fall out in the field you will have to find it, but as it is brightly coloured (providing you dont mix all of the colours together). I first heard about this from the stallion man on a stud years ago, and it works superbly.
The other tricks are cooking spray and WD-40, although that only works if you've got a horse that will let you get near its feet with a spray can.
Goose fat is the old timer's remedy. A fellow I used to ride for swore by it and it worked well enough but it was really annoying trying to tack up with all the barn cats licking the horses' feet.
Don't kid yourself though. In parts of the world where it really snows people shoe their horses accordingly, with special "snowball" pads and borium-type traction additions. Or they leave their horses unshod for the winter.