unqualified joy
As a side note, I think they do understand. A dog would simply think, "My pack is interacting with me, giving me attention, and while i do nothing but enjoy they're preening, it seems to bring them joy, and that makes me happy."
The creature violently moves its forward appendage, removing the deception before attacking and devouring it.
The creature will later violently vomit the deception's remains on the living room rug
It will then attempt to consume them again.