Our cat left and was gone for over two days once. We were freaked out and sad. @Chimera had her for years and this was a first of her being gone like that. The area we lived was a bit in the boonies and lots of owls, hawks and coyotes.
She came home and just meowed at us like nothing was new, like she had just come inside from a short adventure outside.
We have one of those pet GPS collar things for her now. She happened to get out tonight and is somewhere in the neighborhood having an adventure. It is nice being able to see where she roams and that we could find her if we needed to.