For the short version - My horse is extremely irritated by the bits I've tried on him, and I think it's because they're hitting the roof of his mouth. I got a pretty close look at what was going on in there today with a single-jointed snaffle and a curb with a small/medium port, and I even stuck my fingers in there and got the same reaction when I touched the roof of his mouth as I do with the bit. So now I'm trying to figure out what I should do...
So, now what? I only have single-jointed snaffles and the curb bit, none of which work for him. I wonder if a double-jointed snaffle, like a French Link, would work, or if I'd be better off going with a mullen-mouth. I may be able to borrow a Myler bit sooner or later to see how it works (it's on loan to someone else at the moment), but I'd like to find a cheaper bit if I can.
Any ideas or suggestions here?
Now for the long-version with background information, just because I took so long to write it before I realized I could summarize it all in two nice little paragraphs:
My horse has had bit problems since shortly after I got him. I'm not sure if he had them before February, since that's before I bought him, and since he wasn't ridden regularly, I think it took a little bit of regular riding before I realized he was having issues. In other words, he might have always had these issues, but I just didn't recognize them.
What I did recognize was that about a month after I got him and he was getting ridden regularly, he started foaming up each time I put the bit in his mouth. Not the good "oh I like this bit" foaming up, but rather stressed-out-need-to-protect-my-mouth foaming up. It would literally cover his muzzle and drip off his face. It immediately went away, however, as soon as I switched him into a hackamore. Since then, I've moved him in a sidepull, my preferred type of bridle for various reasons, especially since I do endurance and it allows the horse to eat and drink more freely. However, I need to be able to use a bit for training and in other situations in order to communicate clearly.
During the winter, we've been doing some training, but as soon as I put the bit in his mouth, the problems begin. In a single-link snaffle bit, he immediately opens his mouth and pulls his lips back away from the bit. This is before I put any pressure on it at all. When I do put pressure on it, it becomes a battle and he throws his head, sticks it out, pulls down, etc.
At someone's suggestion, I tried a short shanked curb bit with a medium port to prevent any tongue-pinching to occur. When I put the bit in his mouth and let it sit, he did pull back his lips, but not nearly as badly as he did with the snaffle bit. However, when I put any pressure on the bit, he would try to get away from the pressure, open his mouth, and pull back his lips, as well as grind his teeth, but at least it didn't become a head-throwing battle. He just looked and felt very uncomfortable. Today, he didn't pull back his lips at all unless pressure was applied, but it was still just as bad each time I had to put any pressure on the bit.
After riding, I tried to get a good look at what was going on in his mouth. It seems that even the medium port is hitting the roof of his mouth, so he's opening his mouth to get away from it. I stuck my fingers in where the bit and couldn't avoid contact with the roof of his mouth, so I think the roof of his mouth is very low (but I don't have any comparison at the moment, so I'm not sure if all mouths are this low). Then, I put the snaffle back in his mouth. As soon as I put any pressure on it, the joint hit the roof of his mouth (I was pretty sure, but it's quite slobbery in there) and he opened it and pulled back his lips. Finally, I stuck my fingers in there again and bent my knuckles slightly. As soon as they hit the roof of his mouth, I got the same result. In fact, if I just stuck one finger in there and barely touched the roof of his mouth, I got the same reaction. I think I've found the source of my bit woes.