My horse has develped this habit within the last 2 years or so.... my suspicion is that it has developed due to increased stall confinemen? I had to change boarding situations about 3 years ago from nearly 24/7 turnout.  He does it during two situations tho. One is when a horse irritates him in his stall (sometimes as little as looks at him when he is eating) he will pin ears throw head and grind teeth and come at the bars near the other horse. I don't know if he does this turned out. I'll have to go watch for a while. He gets on well with his turnout mare buddy. He is boss but have been together 5/6 years not too pushy with her outside. Was bottom gelding in herd of 8 at a point so wondering if he has food anxiety? Yet is a hard keeper and easily distracted from grain? Picky eater as well.

The second situation is now is when I saddle him or brush under his belly. He will grind his teeth when I do up his girth. Saddle has been checked, regular chiro and vet. He has always hated lots of touchies. Would call him thin skinned (ulcers?). He had been saddled a few times when I bought him but otherwise I've done all his breaking/starting. Was scared of saddle and bridle. Had to work on that. Wondering if I cranked up the saddle to hard quickly in the beginning too? I also used an old saddle for a little while that didn't fit him and was pretty cheap in case he trashed it. He has been broke 6 years now and has never really liked being girthed but the grinding of teeth has happened within the last 2.

Currently performing well. 1D year end barrel champion, open barrel champion and open pole champion in my area. Teeth are done yearly

I just have no clue how to deal with this or what I should be doing for corretions or vet work? Should I buy a new saddle or girth or pad? Does not do it while being ridden.

Thanks

My 4 year old filly does the same thing, particularly with other horses. She's on full turn out but does this when another horse irritates her. I have treated her for ulcers in the past, as she's very tightly wound, and some of her other behaviors improved, but she still grinds her teeth. I've come to the conclusion it's just her thing & try to ignore it. 

Sounds like hes got ulcers and I bet he does with the way you described him I would treat him for them or go and get him scoped.

Sounds like classic ulcers.  It would be worth having his scoped and starting an ulcer treatment.  Then re-scope after to ensure that the treatment is working. 

I agree with the others on treating for ulcers. My gelding was super touchy in the belly flank area too. Ulcer stuff didn't work. I add magnesium to his diet and with in a a couple weeks he could of cared less about the brushing and saddling. Super cheap and easy to add in for a try.

          I had a mare ( she has passed away years ago) that was turned out 24/7, was very gentle and laid back, and she would grind her teeth only at other horses when they rode past her.  She never did anything else agressive towards them.  Just grind her teeth.