Had a vet /chiro recommend this pad to help with saddle fit when using same saddle on numerous horses or on horses whose body shapes are changing. Any experience ,or preference out there? Also what size do I get for a 17.5 inch saddle?
They will help the fit if the saddle is too big to begin with - or if its uneven; then the shims come into play. They come in only one size so far as I know. They can be useful, and I know many people have them. However I personally don't like riding w/ them as I feel much more separated from the horse's back.
Then again, the horse may like that!
They come in small, medium and large, though the small usually has to be special ordered. They also come in dressage and AP/jump cuts, the dressage one being more straight in front to fit the straighter panels of most dressage saddles.
They work well if your saddle is too wide; they are especially useful for a young horse who's still building muscle or a horse coming back from injury/time off who is building muscle/may not be symmetrical.
My 17" dressage saddle takes a medium Mattes correction halfpad. I think the 17.5" would also take a medium, and then 18" and larger is a large, but do verify that.
If you use a square pad beneath the Mattes correction pad, make sure the pad extends beyond where the Mattes pad ends so you don't create a pressure point if the Mattes pad overlaps the binding of the square pad beneath.
The Mattes website has the dimensions - I think I got a large for a 17.5 County Stabilizer. My saddle fitter actually cut the shims to what she thought was necessary (I had a horse that would be filling out).
I would get a large for a 17.5, my medium fits up to 17, but fits best for 16/16.5. I love the pad, it allows me to use my current MW tree saddle on my narrow tree horse while he regains muscle lost from time off. The shims can be used to lift the back or compensate for uneven muscling.
LOVE mine - it's probably the one most useful piece of equipment I've bought in recent years. You can also "flock" the pad with regular loose wool for a horse with a swayback or a serious forward-moving saddle problem. The fitter who originally sold mine to me flocked it for my elderly horse whose body was changing with age, so he could continue to use his own saddle which couldn't be adjusted any further. Now I've completely changed it and use it for my sensitive-backed TB who teaches a lot of kids. If I could afford a second one, or find one used, I'd grab it in a heartbeat.