I have a dog and everything is just fine - he respects Oliver's space, and he always knows the cat is boss, too, I think he feels similarly about the bun. Roy, my dog, is also pretty old and really mellow, which I think is important. That said, I'm getting ready to have a roommate and he'll come with a pug - the pug is pleasant, but neither the bunny nor the dog care for him, at all.
He moves too fast, makes too much noise (not barking, but just general pug noises) and is far too close to the ground. He's a pleasant enough puglet, but I don't think the cat nor the bun will ever learn to appreciate him - it's just not in the cards.