Breast collars are used to keep a saddle from sliding backward along a horse's spine toward the tail. If the saddle does shift, it can effect the horse's performance and lead to pain or soreness in the animal's back. A breast collar is also commonly known as a "breast plate" or "breast strap." Breast collars are used with all types of saddles, and a basic homemade collar is made with heavy-duty elastic and a couple snaps.
Saddle your horse. Measure the distance from saddle's D-ring under the front of the skirt, around the horse's chest, to the same D-ring on the other side. Add 4 inches and cut a piece of heavy duty elastic to this measurement. The elastic should be a minimum of 1 inch wide so that it will not dig into the horse's flesh when attached to the saddle.
Thread one end of the elastic through the square end of a trigger snap that is the same width as the elastic. Sew the elastic back onto itself. Try not to use any more than 2 inches of the elastic during this step. Double or triple stitch the elastic so that it will not come apart under pressure.
Attach the sewn-in trigger snap to one of the saddle's D-rings and wrap the breast collar around the horse's chest. Snap a second trigger snap to the opposite D-ring and run the open end of the elastic through it. Pull the elastic snug, but not tight, against the horse's chest and mark the open end of the elastic where it will need to be stitched to maintain that level of tightness across the animal's chest. Remove the breast collar and snaps.
Stitch the second trigger snap to the elastic in the same manner as the first where you marked it on the horse. Use the trigger snaps to attach the breast collar to the saddle.