I've had my dog (11 years soon) much longer than I've had Simon and Garf. The pigs are on a double stand, which keep them from seeing Snoopy all that much as she enters and exits the room (she's a Velcro dog, follows me from room to room and lays on her beds in the different rooms.
I think the breed consideration made by Freela is a great one; different dogs will react in their own ways. I have no concerns about Snoopy, but would exercise much caution with any other dog. (and no, Snoopy is never really given access to the pigs regardless of how comfortable I am with her)