What's with the dogs? And the bats?

So I watched the movie a couple of times. And I kinda love it.

But I've always wondered, what's with the dogs? And the bats?

Are they conducting dog experiments at the mental hospital? Or is the stress causing Carol to hallucinate? Do bats really attack her in that decaying building, or is she freaking out like she was when she saw the dogs?

OR is this Lucio Fulci film, and I shouldn't ask too many questions?

I once had a handful of questions relating to the characters in THE BEYOND—and their various "motivations"—but was told to shut up because Lucio Fulci logic is a thing unto itself.