I've successfully used the blocker tie ring to rehab an older mare who is a confirmed puller. I use it in a round pen with 50' of rope. They can pull clear to the other side of the pen without getting loose. They lose the claustrophobic feelings and accompanied panic with time because they are never tied fixed. You may never be able to tie her fixed. The older mare I worked with had some seriously crappy experiences with tying. Now she may pull back 10 feet every once in a blue moon but she settles again easily.

"Keep an open mind so that your thinking can be flexible, but not much that your brains fall out."- self