RE: When an animal passes away, where does its soul go?

When an animal passes away, where does it go? Where does its soul go?

I am not overly religious or spiritual, so forgive me for not knowing all the details. "Heaven/Hell" seems to be a mostly Christian construct. More broadly, an" Afterlife" is a more universal Human construct. It seems to me that Man, at the end of his life, doesn't want to be done. He wants to go somewhere. Or perhaps more importantly, the "left-behinds" want something more and better for the "moving ons."

When an animal passes away, does its soul go to "Heaven" (or not)? In which case, there must be some Christian Goodness inherent in animals.

Or does the animal move on to a more generic "Afterlife," where he gets to play with the other animals who came before him?

But if the animal was a pet, his happiness, presumably, was tied to being around humans. So an animal-only "Afterlife" wouldn't be that great. Would the pet go to people "Heaven"?

That implies that:

(1) There is one "Heaven" for everyone and everything. That seems to defeat the purpose of multiple religions. Or,

(2) There are multiple "Heavens": one for each all-powerful deity. That doesn't make much sense as animals, presumably, do not have religious preferences. Or,

(3) There is no Heaven. Because the other options are to complicated.

The spiritual side of me opts for (1). The scientist side of me opts for (3).

Thoughts?