This old song because it reminds me of my Mother and makes my eyes water, like right now.
It says you should not eat animals that have split hooves or chews there cud...It is in the bible....The same origin but somehow 3 separate religions.
Pigs live in filth, eat anything including filth, and are therefore considered unclean. Any amount of time spent around live pigs leaves no doubt about this logic.
I had a Muslim friend tell me once that pigs are physically incapable of looking up toward heaven, so are considered too lowly, beneath Allah's grace.