I did the bringing home the bacon quest, and I got the carrying pig pet. Can this pet carry anything, or do i need the spirit one to hold anything.
The pig pets don't actually do anything. Like every other pet in the game, they are purely cosmetic. The pig familiars are what you are looking for. In particular, the spirit pack pig is a beast of burden.
If you think about it, a pet that actually did any of the things that familiars do would be massively overpowered. Beasts of burden, for example, are useful in just about every situation, so having one permanently for no cost would dramatically unbalance the game in favor of players with those pets.