Help - saddle sliding back

So I have a very nice saddle which I purchased a year ago for my then 6 year old horse. It fit him nicely at the time with just a thinline pad for protection

As he’s grown and muscled up over the past year the fit has not surprisingly changed. It still sits evenly with no bridging or rocking, has good spine clearance and doesn’t seem to pinch his shoulders.

But, unless I use a gummy no-slip pad directly on his back, the sadddle slides back significantly over the course of a ride, as much as 4 or 5 inches.

Obviously he’s going to continue changing at this age so I’m not looking for any radical or permanent solutions, but any suggestions aside from the gummy?

It’s a dressage saddle, foam not wool flocked if that makes a difference

My friend has that issue with her fat Welsh pony. She uses a regular saddle pad. She puts that no slip shelving stuff between saddle and pad. You can get it from the dollar store. Works for her.

BTW do you tighten your girth part way through your ride? Your horse could have relaxed some.

I never think to tighten the girth while riding. Will definitely try that!

I have the opposite problem. My saddle wants to tip forward. I now tighten my girth one more time half way through my ride.

Often when that happens, it’s because people have their saddle too far forward to begin with, and the saddle is sliding back to where it belongs! It should be placed so the tree points are a couple of fingers behind the scapula.