How To Take A Wither Tracing
When taking your wither tracing be sure to use a flexible wire but one that will hold it's shape. Bailing wire and electrical wire work well. Please do not use a clothes hanger as they are not flexible enough to take the shape of your horse's withers. Anything that will start as a straight wire and bend easily enough to mold to the shape of your horse and then retain the shape long enough to trace onto a sheet of paper.
Find the horse's shoulder blade. This bone is called the scapula, and it drops off very noticeably when you run your hand from his shoulder to his back. You want to make your tracing behind the shoulder, where you would want your saddle tree to start. I like to have about 2” behind the blade itself, or 1” behind the “movement” of the shoulder (if you have someone lift the front leg and gently extend it forward, you will be able to find this spot with no trouble. If you are alone, have your horse move around you and look at the movement of his shoulders.
Once you find this spot this is where you should take the tracing. Making certain that your horse is standing square (front feet equal); place the tracing tool of choice over the horse's spine, with about 6” on either side of the spine. We only need about 6” on either side of the spine. Conform the tool to the horse's back exactly, and then put the tool onto a horizontal piece of 8 ½”x11” paper and trace it.
If you want to check the saddle that is currently being used on the horse to see if it fits and get an idea of how and why if it does not, you can take the wire or wires (once you have carefully traced them) and place them within the tree of your saddle starting directly under the saddle horn of a Western saddle or under the pommel of an English one. You are looking for how well the saddle tree and wire have the same shape. The angle of the tree is as important as the width of the gullet since the matching of the angles makes a wider plane to take the weight of the saddle and rider.