I am following this thread with interest as I have known one horse (well-ish**) who. had the tongue issue AND because that one habit/problem is enough to take a horse out of the dressage show ring. (Damn, we have gotten fussy.)
And so I offer an additional observation from that one horse and a whacky idea.
The horse I knew who stuck his tongue out was actually a hunter, and ridden that way, who, I’ll bet, had some kissing spines or similar lurking. He could randomly land from a fence and buck so as to put a professional 10’ in the air. He was sent to me to try and figure out, LOL. The other big feature I noticed was that this horse really internalized his stress. He was big and stoic and, I’d say a bit humorless, so far as I could tell. The two asterisks above about knowing this horse “well-ish” is that I think I got to know him as well as someone could, but that he was quite hard to read. I’m a better horsewoman now that I was then, some 15 years ago and maybe I’d have a different assessment of his mind.
But my point for all y’all is that it seems to me that this horse’s tongue stuff was a form of self-distraction and self-soothing. He lived his life a bit emotionally isolated from the people around him, so when he was uncomfortable with something under saddle, I think he figured out a way to cope with it and keep going.
Also, there are some horses who are more oral than others. So their stress-- good or bad— comes out their mouth. These are the horses who are more into making faces or nipping or pointing their lip than is the average bear. So I wonder if those guys come predisposed to putting their tongue out if they have some stress to express and manage. Another horse would express his stress a different way, say, tail wringing.
Which leads me to my whacky idea: Does a young horse putting its tongue out mean that we ought to be figuring out how to ride it in a different style (at least for that moment in his stress-inducing education) and perhaps in a hackamore or at least a less constricting noseband? If we took all stimulus out of his mouth, would be drop that form of self-soothing before it became his go-to habit? Also, should we take some care with the stoic, “internalizing” horse to invite him to express himself, good, bad or ugly, so that he put his stress on the outside of his body and feel relief from it? I think a horse who felt that his rider can lead him to stress, but also help him find peace from it is that horse who can learn to like his job because he develops self-confidence from being trained.
Also, I’m not deep into the Western World, but I wonder if tongues sticking out is not A Thing there, in part, because they ride their horses with a different bitting philosophy. Don’t get me wrong: I’m sure there is plenty of internalized stress for the average Western show horse. And AQHA’s have been bred to have a different mind than does the average TB or WB. But they are not asked to go around with constant contact that has some degree of pressure to it, all.the.time. Rather, the bit to a western rider is a “signal device” where it’s only moved in the horse’s mouth if the rider has something to say. The goal, then, is for the horse to just “pack the bit around” such that it lies in his mouth wherever the weight and shape of it do in a very comfortable, neutral way, most of the time. So does our style of riding play a part in how these horses develop the habit?
Another trainer saw me on him in the warmup at a show hanging his tongue out and came over and tightened my flash to the point he couldn’t get it out. I don’t recommend that as a fix (or for any other reason for that matter), but it was an expedient that day. Correct riding is what cured him of that habit and he never did it again, even at shows or under stress.