Difficult pony- how would you tackle this problem? (also in NL)

[sfward]

I'm helping a girl at the moment who has a 7 year old Connemara mare. She's a sweet mare, totally bombproof and fun, but has had no real flatwork training and is very stiff. She also has a very thick neck and jaw with quite a lot of muscle on the underside of her neck which she uses to set against her rider. She is lovely and relaxed in walk but as soon as you ask her to trot the problems start - she basically goes all inverted and tense and the rider just can't do anything with her so she just trots round with her nose in the air. It's not helped by the fact that the rider broke her back about a year ago and is therefore quite weak in terms of core strength, and struggles to keep her hands still, her position solid and maintain a consistent contact. I've ridden her myself and I can get a tune out of her just because I'm more experienced and a lot stronger in my seat and leg aids but it's very hard work, and even I can't do anything with her in canter! She just wants to arge with you the whole time, it's exhausting!
How can I help her to get the pony working better, in a more relaxed, round way rather than fighting with her head up all the time? Long reining seems to help (but I have to do this as the girl isn't confident doing it herself) and I've suggested lunging in a chambon to get the horse working over her back and developing the right muscles, but I need some more ideas for ridden work. I've introduced her to lots of serpentines and bending, flexion, basic lateral work etc though at the moment it's only possible to do any of this in walk. Any ideas greatly appreciated! Part of me thinks she might benefit from some lessons on her position, eg. lunge lessons etc but I'm not sure I would feel confident doing this and wouldn't know who to suggest...

 

[nikkih]

Have you tried lunging the pony in a pessoa? My friend has a major problem like this with her horse - couldn't do anything in canter and trotted around like a camel! She was told by her instructor to lunge in a pessoa 3 times a week and it seems to have helped.

 

[kerilli]

i'd get her checked by a mctimoney first, fighting all the time isn't normal tbh, she should find it comfy to go correctly.
the thick neck and jaw won't make any difference - if they're comfy, they can soften very easily at the poll and jaw, and not use it against you at all. lots of the Iberian horses have that conformation and it doesn't stop them rounding into the contact.
i'd have a play with different bits (are the mare's teeth 100%?) too, see if she'd go much better in something else. maybe even let the girl school her for a few weeks in something like a myler combo (with comfort snaffle mouthpiece) that really helps stop them poking their nose (and worse), give them both the idea of a light comfy round soft way of going.

 

[sfward]

She's been checked by a back specialist (no problems) and also had her teeth done. My impression is that she's just taking the p, but maybe I need to go a bit more back to basics with her.
She's currently in a loose ring french link, I have suggested changing bits before, will mention it again, the myler combo is an interesting idea. Some people in NL have suggested a de Gogue, any thoughts? Not sure whether it would be suitable for a less experienced rider?