Join Date: May 2009
Location: Mid Northern TN
Your horse looks irritable when you put the saddle on him because it doesn't fit. It's not bridging- the top of the tree is too narrow, so it's putting far too much pressure at the front and top of the bars, resulting in the dry spots you're seeing. Adding more material between the horse and the saddle (half pad) is like putting thick woolen socks on and then trying to squeeze your feet into too small shoes, thinking the extra padding will help! It only makes it worse, not better. If he's been putting on condition as well, it's likely the fit is only getting tighter and tighter. Ditching the half pad may help.
It may not though- it looks like the bar angle is too flat, basically, the angle of the saddle if you're looking at it from the front is wider at the bottom than your horse, and then as it narrows towards the top, it finally makes contact in one small spot (the dry spot) rather than the whole bars spreading the weight. It looks like you can fit your fingers between the bottom of the bars and the horse, and then it presses tight into his withers at the top.
TL;DR: The saddle does not fit. You're going to need a different saddle. There's really no corrective padding that's going to fix that basic fact.