The movie perfectly portrayed how it feels to lose something you deeply love, searching and searching for the one thing that brings you happiness and company even when you don't realise it, to find out that it was all in vain. It captured the feeling of complete loss of something or someone you deeply love, even if they are just a pig.
I think it teaches people to not undermine just how much you can love an animal, and that the relationships you can have with them aren't just superficial, but like family.