Place the saddle on the back and slide it back to where the conformation stops it. This will indicate where the saddle will slide back to when ridden. The front edge of the tree must be positioned away from the back edge of the horse's shoulder blade when standing. Approximately one hand should fit between the girth and the elbow. As long as the girth lies ahead of the back of the sternum.
Pressure on the scapula will restrict foreleg and shoulder movement. Having the saddle too far forward can weigh down the horses forehand.The saddle must not be placed on the blue or red lines. The contact areas of the saddle must touch the area in between the lines.
The saddle can only extend back as far as your horses last rib, thoracic 18. The lumbar area behind the last rib is not for weight bearing.
Picture on the left saddle is placed in correct position. Saddle on the right is too far forward sitting on the shoulder blade restricting movement