Sorry, should have replied with quote, this is to Tnavas' last post:
That can also come from the horse being more A framed and the saddle being for a back that is wider side to side, sometimes narrower seats and panels allow the saddle to sit on the higher part of the back and keep it off the spine. If the fitter tries to flock more into the centre to correct this issue it can cause instability ie rocking or slipping. Sometimes a spine free sheepskin pad is enough to give the space for the horse to lift it's back, but it's why I hark on about flat trees all the time, if the tree is curved you have to keep the flocking light in the middle (if it can be made stable at all) and that can have downsides, especially on A frame horses.
