My pup doesn't sing to it, but funnily enough when it was on the other day he suddenly started paying attention to the TV, which he does here and there anyway but this was probably the most attention he's ever paid to a TV show.
I wonder if there's some subliminal doggy message in it!?
My current dogs rarely sing, although once in a while they sing back at the coyotes. When I was a kid, the dog wanted to sing along every time I practiced playing my saxophone.