I've wondered about this as when I'm on the way up to see Paarth it's not uncommon for an unnoticed mountain goat get into the path of the Clear Skies shout. When this happens the goat doesn't get hostile as though I've attacked it (I presume they would do so if provoked) however I do get a health bar for it that shows diminished health for a time. I once felt so bad about it that I chased the little guy around for several minutes trying to cast Healing Hands on him.

Up til that happened the first time it never occurred to me that a "non combat" shout like Clear Skies would do anything to the health of someone who got in the way of it, but apparently it does.