Yeah, the worms do come out when the dog has been wormed, or if he has a huge load of worms. I recommend you get a couple of extra treatments of panacur just in case; roundworm is disgusting, and they can cause blindness in children.

It can't hurt to have a vet look at him anyway. Make sure he is healthy and such.

Give your puggie a chance. He'll never replace the one you adored, but he will offer his own charms (after he's stopped pooping worms of course).