Horse getting too excited when schooling

[JCGiamoonah]

I have an 8 year old Arab mare who up until this year I have only competed show jumping and cross country but never much on the flat; I decided I wanted to try and work towards doing some eventing next year so have spent this year really working on our flat work. She works beautifully in walk, trot and the first canter of the session, however, after the first canter it's almost like she loses concentration and will run into my hands, over bend, set herself against me and jog constantly. I was wondering if anyone has any exercises to help me combat this?

TIA

 

[be positive]

If you are certain there is not a physical reason for this, the wrong saddle can make cantering uncomfortable even if they are fine in walk and trot, then I would possibly try a different approach and use canter early on in the warm up, light seat so she can really move under you, and keep her cantering until she wants to trot then do more, once she has really relaxed in canter come back to walk and start to work her, it may take a few sessions but if you can get her really relaxed in the canter it should become less of a big deal and she should start to accept your aids better.
We often don't do enough canter work and it becomes the "exciting" end to a schooling session, with the issues you are having I suspect she has been revved up a bit and mainly cantered when jumping.