I had a mare come in for training that tried to kill the horse in the stall next to her. I couldn't turn her out with any of my horses but tried putting her with my two mini mules. She ignored them and paced the fence like crazy. She had many issues including anaplasma (tick disease) but also had hormone problems and some kind of head injury. She spent a couple of months with the vet just to sort every thing out then went home where she lived by herself.
Have you tried (zipping up flame suit) homeopathy or an animal communicator? Definitely worth a try IMO for something like this.
My gelding does this when he's bored or wants to come inside. He's quite frantic if he's turned out alone (he has one buddy) and can't see the two other horses in another field. He also stall walked the entire 5 months of suspensory rehab stall rest.
I think it is an OCD thing and once they start for whatever reason, they just don't stop. He sort of tunes out everything and goes on and on. Never noticed weather changes causing it unless he wants to come in because it's raining. He had been pasture boarded for many years but now likes being inside.
I do use an AC and will ask during my next session. A boarder used one and she told me her horse found my horse's pacing annoying.
I haven't tried homeopathy or any alternative therapy yet.
I confess, I have had a chat with an animal communicator. Should one admit that on a public forum? She didn't tell me anything I didn't already know, except for the bit about my horse and I competing in cross-country (this was news to me). Because I was trying to be somewhat scientific about it, I didn't prime her with any specific information about the horse, other than her name. I certainly didn't ask "why does my horse fencewalk?" After all, most knowledgeable horsepeople can make reasonable hypotheses as to why a horse might fencewalk -- you guys on this forum have done and you're (probably) not psychic -- and at the time, I was interested in whether or not the AC could tell me accurate information about the horse.
I'm thinking of picking up some moody mare supplement and trying that. I know it's different stuff than magnesium or vitamin B12 calmer and I'm not sure which to try first. But either one is the easiest place to start, as I can grab some from the local feed store.
Watch ingredients and manufacturers closely. My daughter went to the feed store to get Cool and Calm for her boy, they were out and she bought the store brand. After a week of crazy, she got the real stuff and things have smoothed out considerably.
I've had nice results for stall walkers with Magnesium. Used Mag Restore, but it is a bit pricey. Vita-Calm has magnesium and other stuff in it and works well. The good thing is that once the "magnesium balance" is restored you don't have to continue with the product.
Of course, not all products work for every horse and some habits are deeply ingrained.
I have a youngster that struggles with wind, non stop gallop, buck until he works himself in a sweat and I give up and bring him in.
I used not to be able to turn him out at all, even with a shed & tons of hay.
I tried every calming supplement under the moon and even resorted to Ace-ing him.
He's quite treatdriven however.
So I tried to use that to my advantage.
It's been very cold here lately twenties daytime and gusts up to 45mph on some days. I figured I would have to keep him stalled all week.
But I bought a few of those nose-it treat dispenser balls (http://nose-it.com/) which I filled up with Blue Seal Carb-guard (lowest cal-nsc) and timothy pellets.
He found those ever so interesting and to finish all 3 it took him over 2 hours Result : wind, what wind? Was it windy today, really?
I nearly had tears in my eyes to see him so quietly roll that ball around in those insanely cold winds. He didn't even go into the shed.
Perhaps finding something to keep the horse occupied might help.
I have a rolly treat ball. That's not a bad idea, though I'd worry she'd roll it under the fence and into the neighbour's field. Then they'd get the treat ball and she wouldn't. Does your guy send it to the neighbours occasionally?
I worried about that too, so far he seems smart enough to keep the cubes to himself. He's not violent about them, and gently noses them around.
The ball is more a cubicle type of thing, so it only rolls over one side at the time. If it were a full rolling ball it could indeed end up rolling into his buddy's paddock.
If it were to become an issue I might put down a few woodbeams under the fenceline and consider it a permanent thing.
It's worth a try, I hadn't expected such a dramatic improvement, seemed too simple to work, but as by magic it totally changed his focus.