Oof - a lot to unpack hereā¦
The curb cannot get to such an angle (Iād say 50-60 degrees from its resting position under no tension) without the curb rein being pretty darn tight. If that isnāt āoverly tightā Iād really hate to see what is. For reference hereās a pic of a similar bit at rest:
Compared the image in question:
We donāt know how big the port is, but we know from the angle of the shank it will be rotating into the roof of the mouth, which would explain the horse gaping in attempt to escape the pressure (against a crank noseband no less). We also canāt see how tight the curb chain is, but based on the angle of the bit, can assume the horse is simultaneously having his lower jaw clamped between the mouthpiece and the curb chain. I suspect this is the cause of the blue tongue, unless the port is perfectly shaped for this particular horseās tongue, which is doubtful. All this while the distance between the horseās poll and the mouthpiece is shortened, creating a vice-like pressure between the mouth and the poll. Itās an awful, and sadly all too common, image of a horse attempting to escape discomfort coming from many directions at once.