Spine shots used to be commonly taken, moreso for plains african game, but you still can read articles from 30-40 years ago advocating them for US hunting.
If you hit low, it will make a mess of the insides. I have taken rear spine shots at close range (inside 50 yards) but you will have to make a finishing shot.
Anymore, I would a rear presentation, unless at spitting distance. 100 yards is a long way for such a vital small target.