You are going to need a better picture if you are trying to prove he's too skinny. I can't see his ribs, he looks heathy to me.
You need 2 shots of him, both standing. One from above looking down, the other directly from the side from nose to tail. We want to see a waist and tummy tuck.
Be aware, the vast majority of dogs in the USA are FAT FAT FAT so our mental picture of a fit and healthy dog is messed up when we are seeing fatso dogs all the time.
Great Danes and GSD's can both look lean and lanky and be HEALTHY.
Look how skinny this boy is!
MACH3 Bretta Lee Wildhaus MXG MJG MXF MFB TQX HIT CGC TC
Glory B Wildhaus AX, AXJ, XF
"Behind every great man is a woman rolling her eyes." - Jim Carrey