SLIPPING SADDLE PADS

I purchased a "gently used" saddle recently, 2yrs old. a Sattle Rheinfelden"ENGAGE" dressage model. It has very long straight billets, the front one lays just behind the small thigh roll on the underside of the outer flap ;I've a thick  quilted square dressage pad, a dressage square shaped for a high withers and both during riding "creep back" towards the saddle and/or bunch up, on either side. The shaped high-wither pad is pulled towards the saddle from behind. The mare I ride  has high narrow{ish} withers and a long  back and. The saddle gives good clearance over and around her withers and the panels sit evenly on her back with good clearance for her spine, it's a 171/2 med tree, but what to do regarding a saddle pad? ..and I'm very careful when I position it on her back and girth her up.

Often, but not always, a saddle pad problem like you describe is due to a saddle-fitting issue OR the pad will creep on only one side, which is usually a straightness-of-the-horse issue. Without seeing the horse and saddle, I can’t comment on your saddle fit, but assuming the fit is satisfactory, you can concentrate on the pads themselves. I would suggest a ‘non-slip’ pad, like the Barnsby ones, could be a good solution – they don’t slip on the horse’s back, and the saddle can’t slip on the pad. They have some substance to them, so they are less likely to bunch up, the fit most horses well and wash well. Trying a somewhat thicker pad – perhaps with felt or similar interior which gives some firmness to the pad, might help. Otherwise, you may need to add to the fastenings on the pads you have – look at having a Velcro strap that fastens to the breastplate D near the stirrup bar, the regular fastening to the billet(s), and a girth loop – if the pads are still sliding around with 3 fastenings, I would revisit saddle fit - while the saddle may be the correct fit for the horse, it could need re-stuffing.