That is one interesting picture.
A full load of heavy buckshot, through and through, and the deer did not crumple. Nine, what.... .33 calliber holes on a yearlng deer that weighed maybe 75 lbs, live?
I think the blast of a firearm, in addition to what ever else they might feel, startles deer so completely that they flee madly if they can. DRT is not a common experience with my hunting and gun kills on deer, , unless the shoulders, or as you say, CNS gets clipped.
Conversely, I've watched deer, double lunged by an arrow, flinch and resume feeding, or "sunfish"/ bouce, look around and drop. Not always, but often enough its no longer a surprise if they do not react.
Well done , BTW to pattern your gun, shoot within its range and follow up.