I feel for you, as I’ve spent pretty much the past year sorting out my guy and addressing every possible issue that could be making him a bug-eyed, snorting monster when he’s normally a google-eyed (hes an app), loving sweetheart. Saddle fit, feet, and diet were all addressed and he pretty much came around and returned to being his sweet self.
BUT, he has occasions now and then when he goes a bit bat crackers. It’s usually something I cannot figure out or understand, but for whatever reason he’ll suddenly be ultra reactive and hypervigilant about his surroundings. This is mostly in the barn, where he only spends a little bit of time being groomed and tacked…he lives outside 24/7 and wouldn’t have it any other way. You’d think he’d been captured from the wild instead of born in a western pleasure show barn down the street, LOL!
Anyway, getting him a properly fitting saddle, changing his diet to a much lower carb (thankful for a BO who was willing to change feeds to accommodate my critter), putting him on SmartCalm Ultra for the magnesium and tryptophan, and especially getting a new barefoot trimmer who has performed miracles on his feet that have also helped his back (which I feel was one of the big factors in his behavior)…all have helped.
Like others here, I have also noticed that he’s a happier fella when he’s kept blanketed if it’s chilly and especially wet. If it’s sunny and cold he’s find, but even 50 degrees is too cold for him if it’s raining…he’s a miserable mess.
One thing that I find interesting about our two cases though is that my horse suffered the loss of both of his best friends and herd mates…one on Christmas Eve 2018 and the next on Labor Day 2019. It was after the loss of that last buddy that I sold the farm where he’d lived for 11 years since he was a yearling and moved him to the place we now board.
I can’t be sure, and maybe I’m being silly, but he was lost without his two “big brothers” who always looked out for him and basically raised him since he was a yearling. He never had to worry about anything, took all of his cues from them, and lived a carefree life back at “home.”
At the new place, he’s been turned out with various combinations of pasture buddies, and he always gets along with everyone…sometimes TOO well (gets a bit of separation anxiety with some). He really had a hard time figuring out his place for a while, and wound up taking on the boss role at one point, which really stressed him out. He seems to get very concerned about the welfare of certain horses (one mare and gelding in particular that he bonded with when he was out with them).
I often wonder if losing his two long-time best friends has left him a little anxious? Maybe he has some sort of PTSD. He really freaked out the day his last buddy died, it was so sad to watch. And since we’ve been at the new barn, TWO horses have died (oldies that were put to sleep). He wasn’t particularly close to these horses, but still.
If your older gelding was the herd leader, your younger guy might be feeling very lost and vulnerable right now. I understand not being able to get him another buddy right away, but I wouldn’t discount how big of a life-changing event it was for him to lose that other horse. It’s more than just loneliness. He’s lost his “herd” so-to-speak and that makes him vulnerable…which can definitely cause the behavior you’re seeing.
Just some thoughts. I hope you figure it out. It’s no fun, I know.