Seven Books in Seven Days #6

This is the second to last entry in this series I've been running on weekends, where I talk a bit about the seven books (or series) that most influenced me growing up. See previous entries in this series here: day one, day two, day three, day four, day five. This will not be in any particular order, as it's hard to put these seven in any sort of favorite to least favorite order.

Does animals as the main characters in fiction automatically make the book middle grade? Or a younger YA? I mean, the Spirit Animals and Warriors series are vast and I think are middle grade, maybe dips into more adult ideas. I haven't read them and I think the time were I would have passed, but feel free to convince me otherwise! But then we have Animal Farm, which is decidedly not. You don't often see adult books that center around anthropomorphic animals. Is it childish to see them as such?