[QUOTE=beowulf;8672790]
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The reason why it is verboten is because it is a symptom of discomfort. I am not convinced it is ever a ‘habit’… I have seen many times before horses who’s owners insisted it was an ingrained habit stop the second their pain was addressed. Usually it is hocks or stifles, IME, though I would not rule out back pain, kissing spine or saddle fit. One horse I knew that was a chronic-waggler stopped once he was started on a course of ulcergard. It could be something as simple as the horse not caring for the bitting/noseband combination.
The quickest way to stop the habit besides addressing the pain is to stop allowing it to happen. Switch her bit to a bit that does not allow that, put her in a drop or some other supportive/stable noseband, and get her checked out by a vet. Having a horse that sticks out its tongue sucks, and I sympathize with you, but make sure you exhaust all possible avenues of pain before declaring it a habit. It’s not particularly comfortable to stick your tongue out and wave it, so I am not so sure it is a habit so much as a learned evasion/distraction because something hurts.[/QUOTE]
Picking one’s cuticles till bleeding, cannot be particularly comfortable, but some people have that habit.
Having known an OTTB that did this from day one, despite changes to the bit, and various types of dropped nosebands etc. The owner was told by a BNT, and O judge," ignore it". Sometimes when being ridden the horse got involved in what she was doing, and would forgot to hang it out. On those days the horse scored in the 70’s.
So perhaps not always pain, sometimes a habit, that sometimes they can be distracted from.