I recently bought a new saddle for my horse, and had the saddle fitter (who is also a vet, acupuncturist and dental specialist) out to get it re-flocked. As part of the process, she did a simple acupuncture exam and noticed that he was sensitive on his 'heel points' (which are on his neck and girth line). She told me that a response in those points almost always indicated heel pain, and looking at the shoes on my horse, said she thought he needed MUCH more heel support than he was getting from his current set of shoes. Out of curiosity, she put acupuncture needles into a spot right above each coronary band ('ting' points). He immediately stopped flinching at the points on his neck, and the spot on the girth was significantly less sensitive. I've never used acupuncture for myself or my horse, but this was a pretty convincing demonstration.
I've been trying to solve my horse's girthiness since I got him about 6 months ago, looking at everything from my girthing technique (no one tightens the girth more slowly than I do right now!), saddle/girth fit, ulcer treatment, training issues, etc. and have had no improvement at all (except that he behaves better for me than he does for my trainer or saddle fitter). He pins his ears back as soon as he sees the saddle, won't stand still, threatens to bite, and sometimes threatens to kick. I never before thought that this could be linked with the condition of his feet.
It's not a surprise to me that his feet are not great- he came to me with feet freshly trimmed by the seller (who is not a professional trimmer or farrier). My trainer spotted a rather large pile of trimmings at his place when we went to see him initially that appeared to be from his hooves, and judging by how slow his hooves were growing when I got him, he hadn't been trimmed in many months. Every visit with my farrier, I've been expressing my concern that I haven't been seeing much/any improvement and was on the fence about whether or not I needed to find a new farrier.
After talking to the saddle fitter vet, I talked to my regular vet and a couple trainers at the barn (and also got a 2nd hand report of another farrier who comes to my barn and had seen Garzo before) and the consensus is that my current farrier is not doing him any favors. So I've gotten a couple recommendations on new farriers, ordered bell boots (since he'll likely need them once he is shod with good heel support), and will try out one of the new farriers once the boots come in.
I really hope the new farrier can do a better job with his feet. And who knows, maybe once he's actually doing a heel-first landing, maybe he'll stop being girthy, too!
My DH caught a good picture of my horse's obvious toe-first landing at our last show: