I'm not a trainer, and I would recommend you consulting with one. What I do see is that he has learned that panicking and fighting (leading to broken ties/halters) gets him the release he desires. As a result, he will escalate that behavior that was successful (in his mind) and will continue to panic and fight until he learns a better tactic. He doesn't realize how dangerous the behavior is, and how he could be hurt it.

This is going to take a long time, but you need some professional level help for it.

I'm not disagreeing with the positive reinforcement ideas at all. What I do see some concern with is that this isn't an "always" kind of behavior if I read the OP correctly.

That means to me that there is a trigger (likely pressure from the halter as a result of being tied). From there, I think that some plan needs to be implemented to "retrain" the horse regarding what that trigger (or pressure) means. IE it should mean to the horse Pressure on my poll...if I lower my head and lean forward it stops. However, I think this horse reads it more like Pressure on my poll...Brace, panic, twist, fight, and it will finally give way.

I am not sure just standing tied without that trigger and rewarding it will be the effective path to stopping the problem.

My old cowboy clients would likely tie this horse with a rope halter to a tree with a tire and let him fight himself to exhaustion. Which I do not recommend.

Pip

I am going to preface this with again, I am not a trainer. I may be pulling stuff out of my behind as well, so take my advice with the grain of salt it needs . I do however own a Thoroughbred and understand spookiness a bit.

I am going free form some thoughts, if they seem helpful then great, if not, then don't try any of this.

If he is spooked in other places besides the barn/trailer how does he respond?

I have found with my mare, I essentially "ignore" the spook and return to work and she returns to relaxed. The bigger reaction I have to her spook the more spook she has.

Round penning may well be a great place to work with your horse in order for him to learn to relax, trust you, and look to you for direction when the "mountain lion" shows up. I would also do a lot of in hand work with him. Set up some cones for patterns, cross poles, etc. Things that he has to focus on in order to accomplish the task you are after. If he gets upset during that and spooks let him move, don't try to hold him still. Circle in that area till he decides to stop (lots of praise as he refocuses on you) and re-approach the task, maybe turn just shy of the spook point, and slowly advance forward till he does it. Don't get upset, don't get loud and certainly don't reprimand/correct. Just be the leader, be calm and show him the "face" that says there is nothing to worry about. The sooner he sees you not worried, the sooner he won't be worried. Even if he is not spooky in these type of situations it will build your partnership and he will be more willing to trust in your judgement. I feel for you with no indoor and harsh winters as I live in the snowbelt of NY.

You probably do need to continue with the desensitizing to the head shy things that seem to bother him. I would also work with some teaching him to drop his head when pressure is put on the halter. Do it slow, with gentle pressure and here I would reward with whatever makes him the most happy, be it food/praise, or a special scratching place. My mare is both very verbal praise motivated as well as food motivated.

I still think advice from a professional is going to be your best option. Make sure you feel comfortable that the trainer isn't going to "cowboy" it (although many cowboys I know are great, sensitive, and patient horsemen).

It's great that you want to do something so helpful for your horse.

Pip

Good luck with everything. I am hoping this winter isn't too bad. I need to get my girl's strength back up now that she's feeling better. I am dying to get on her because she is moving like I haven't seen her in the 2 years I have owned her. That forcing myself to be patient and enjoy our lunging and liberty work is killing me.

It sounds like you have some really good ideas and plan of patience in store. I am sure these panics will become less and less.

Keep us posted.

Pip

Thankfully it isn't really bad. For about a year she has been showing signs of discomfort and unwillingness to work, but we couldn't localize where. Between 3 vets, chiro/acupuncturist, 2 high level dressage trainers, 1 professional eventing trainer we couldn't figure out where. I had gotten to the point where I was trying to find her a retirement home (and she's only 7). Labor day weekend she FINALLY went lame. She has an old slab fracture in one of her hock joints (which probably happened when she was in race training and why she was abandoned at the track) and some arthritis. Injected hocks and within 24 hours it was a new horse. Now we just need to get some fitness back .

My trainer really helped me with lunging too and liberty work. I love that I can free lunge my horse in a regular arena and have her track like she is in a round pen. It's amazing. We are starting some long rein work this week to see if we can straighten out some while building strength. It's just hard being patient because she looks it will be fun again to ride.