A lot of horses are afraid to be tied up, because they know they are tied up and have almost no chance of getting away if something should happen. Most of the horses at the horse camp I volunteer at are afraid to be tied, especially Sundance (because she was abused). We leave a good amount of slack (but not TOO much) and wrap it around the (horizontal) post only once and don't even tie it so if they freak out, the rope loosens up and they think they aren't tied, then they stop pulling and freaking out. We also give them treats while they are tied up like little pieces of carrots.