Not only that if you go for one of the really big ones (I mean "go for" as in to have one as a pet, not as a date) they have the nearest sized organs so if you score some pig love, eat said pig for dinner, have pig-ingesting related heart problems then you can just swap hearts. Jobs a good'un.
Edit: Dogs can look up, they just have to roll over first. Pigs cannot look up however.
Some say he's half man, half fish. Others say its more of a 70/30 split. Whatever the percentage, he's one fishy bastard.