Your horse changes dimensions during the year from summer to winter as well as when they age. Ideally you should have your saddle checked 2 times per year. Not having your saddle checked is a major cause of subluxation and sensitive back. Not to mention this will cause you to become off balance further aggravating the situation.
As a writer for Centered Riding, being a rider, instructor for animal chiropractic college, and practioner for 30 years, I have a great insight into the bio-mechanics of you and your horse.
Please call me at 781-337-1180 or email me at Indekchiropractic@gmail.com