Kristen. We have an old Passier dressage saddle that fits our Icelandic very well. She seems to like it and be comfortable in it. It is not particularly comfortable for me, but our grandson loves it and goes for long mountain trail rides in it on his Arab endurance horse.
It was purchased used and I have no idea of the seat or tree size, but it was used before on a a 16.2 h warmblood. Tosca is 13.2. Nancy
