I have a wonderful 16.2 Warmblood x TB, aged 9, and we are just starting out as a new partnership (I have owened him now for just over 12 months). He has alot of experience, prior to my ownership in the eventing sphere and he did really well, but I wish to concentrate just on the dressage (at prelim/novice level) and a bit of showjumping, but only at local/club level. My problem is keeping him straight and collected on the left rein in canter and he turns his quarters in to the inside everytime we ride down the longside of the school which is very noticeable in the school mirrors and subsequently I end up being shifted in the saddle; I am struggling to sit correctly because of this. The right rein is completely different and very balanced and collected.
He has recently had his back checked, his teeth done, and the saddle has been reflocked and fitted within the last month and I ride him in a kk ultra.
All the information you have provided is very useful. I don`t expect he draws the left rein forward and must learn to do this and stretch the left side of his neck. A useful excercise is to leg yield left in trot and canter with lots of bend right and the quarters trailing so that he uses all the muscles he doesn’t use when cantering left with quarters in! I would make sure he understands the shoulder fore position in walk and trot and then straighten him in canter after a few days. I would think that at his age his muscles would not have developed evenly even if they are clinically sound. However, with correct work and plenty of suppling exercises, his muscle development can be improved.