Ok. I own a 15.4hhish Arabian mare who I bought 3 months ago in a starvation case. I have been noticing on the wall of her back leg near her flank and stifle there is a dent. It's on both sides. I am not sure if it's just were she needs more muscle or what. The internet didn't help.
Twhgirl2, if you want any suggestions please post the pics. It's really hard to imagine anything without seeing a horse. BTW, my horse has a deep on her left just next to the shoulder. Muscling didn't help all that much - that's her conformation, so I just use extra-padding there (per the saddle fitter suggestion).