http://www.horseandmuletrails.com/index.html

http://www.packsaddleshop.com/packingtips.html

The 2d link has an article about packing meat. They talk about the problems with antlers. I haven't tried it but I've wondered if it wouldn't be a good idea to take along some soft hose of some kind and a roll of duct tape to pad any points that could gouge a horse.

I think it would be best to figure out how to pack the antlers so they could not come in contact with the horse.

I don't shot elk big enough to drape the antlers down over the sides of a horse.

I was thinking more of protecting the other horses, the ones that are supposed to be in line but decide to try to pass.
Naw, a horse wouldn't do that.