Hello, the new horse I got is 8, and hasn't been touched hardly since she was 4. She was obviously still green and is doing very well now. I have noticed she is much stiffer in the left, when I want to turn etc. However, previosuly someone must have really ripped into her mouth, she has an old scar on the left side of her mouth and it is more droopy like it is dead tissue or something lol... I am not sure if this may be the cause or if she is just more stiff turning left. We have been training on barrels and she is doing nicely but it was much easier getting her to do the first barrel turn since we go to the right. Doing the second and third we are not doing as well. Is there any exercises I can do to help her loosen up going to the left and to be more willing to give her head that way?

I'm not a 'trainer' but I do train my own. Take that with a grain of salt ;)

I love groundwork, I think just flexing them from side to side, on the ground with a halter/bridle, in the saddle. I do it NONSTOP when they're learning, every chance I can I flex them. I also have done the hay bag on the side of the saddle trick and that really helps stretch them out (I do saddle them right when I get home from work, put the  hay bag on the saddle on the left side and show it to them). While I'm putting my 'work' clothes on and getting a snack, they stretch themselves out. 

In the saddle, i really like circles. I do drills with my green horses using cones and barrels moreso than my 'patterning/finished horses'. Setting some barrels up and doing all lefts will help. Don't nitpick, but don't be afraid to correct them right away either. Hannah Kauffman has some really need softening exercises and drills on her facebook as well!

If it looks like someone has been yanking on her mouth, I'd get a chiro out. My horse gets stiff going to the left sometimes, and once the chiro comes, she loosens back up. Could be poll, C-spine, withers, anything. Also, make sure her teeth have been maintained.

After she's confirmed to be physically feeling good, I'd focus as much as you can on using your legs to shape her up. Remember, you don't need her to be a half circle with her body, you just should be able to see the corner of her eye, elevate her shoulder, and drive the inside hind leg underneath her. If she stays stiff to the left, switch her and run to the left barrel first.

I have had one come out twice for her. :) She just tends to "brace" herself when turning left like I'm going to rip into her.

Also with ones that stay that stiff to one side - it may be helpful to go to the left barrel first. It's a little easier to adjust/shape one going to the first barrel, plus then you're only turning their "bad" way once...

hmmm great idea bout the hay bag! lol

First, check the teeth. Once that is clear, I would start her in the round pen with her head tied gently around one side at a time. She will learn her own release. Do not tie too tight at the beginning if she is struggling to understand.
Also start trotting/loping squares. Do the quarter turn, sharp. Then release back to the straight away. It is a good way to not keep them bored on a circle and they learn how to use their hind legs to get down through the corner which comes in handy on the pattern.

If she is significantly worse to the left than the right I would go left first on the pattern. As a rider we have much more control on approach, angle and ability to turn that first.

Ditto previous posts.

I got a gelding who tends to be stiffer on the right. He's 13 (almost 14), and he's mainly a head horse. He's an All-around guy, and barrel racing isn't his main thing, so I'm not that worried about him coming out stiff at the pattern.

I do a lot of flexing with him during his warm up, and a lot of circles (especially to the right) He gets his proper dental work, aswell as a chiro 2-3 times a year. I tend to switch between a correction bit and a mullen mouth as well.

Check the TMJ

Has she had her teeth done? I have had that help MANY. My 4 year old came to me super stiff on the left and when we opened her mouth she had a nasty wolf tooth on her left side only. It took some time but she is now much better. I also had an 8 year old in training that was stiff and had a terrible attitude one direction. She had an upper hook in the very back of her mouth that dug in to her lower gums and kept her from being able to move her jaw freely. 

For myself, I would not have this horse on the pattern at all right now. First, get her broke away from the pattern. Get the stiff side as good as the good side. Focus on good training and a good foundation.

Horses will always naturally have one side that is better than the other. It's our job to figure out which one that is and then use it to your advantage on the pattern. Usually, you want your horse's better side to have two of those in the run, rather than one. So if this horse is naturally better to the right, then probably plan on her being a lefty.

If you haven't already, I would also be taking her to a vet for a baseline lameness eval, to look for any potential issues, and of course, have that mouth/teeth looked at.

Yes we just got her teeth done in the spring.