• The dog wags its tail only at living things. A tail wag, the equivalent of a human smile, is bestowed upon people, dogs , cats, squirrels, even mice and butterflies. - but no lifeless things. A dog won't wag its tail to its dinner or to a bed, card, stick, or even a bone.

    Jean Craighead George: The dog wags its tail only at living things.
A tail wag, the equivalent of a human smile,
is bestowed upon people, dogs , cats, squirrels,
even mice and butterflies. - but no lifeless 
things. A dog won't wag its tail to its dinner
or to a bed, card, stick, or even a bone.