From a biblical perspective, if we look at the creation account, no animals were meant to be food. (Genesis 1:29-30) They were also not put here just for us, as many Christians seem to think. All things were created by and FOR God. (Colossians 1:16) But the bible does say that God wanted mankind to have a companion, so although animals were not created simply for us, I believe that one of the reasons God created animals was to live alongside us... for us to love and take care of them, not exploit the hell out of them for our own selfish reasons.
And btw, pigs are even smarter than dogs, and just as social. So I see them as no different than dogs or cats, at least in all the ways that matter.