From the Internet:
The word pig has many origins. It comes from the Anglo Saxon word pecga, and the Log German word bigge, both meaning pig. The Medieval Dutch words were bigge, big and finally, pigge, which became the Middle English pigge. Now, "pig" is used to describe a young swine, or a swine in general.

I can't find it on the Internet, but "swine" has to be from
Latin "sus".