What is simple green?

The reason I'm a little more worried than normal is that Sam's had LESS table food than she normally does the last two weeks or so. And she's NEVER gone in the house before, even though she's had diarrhea before.

I know to you other dog moms out there, I'm being silly but this is a really new situation for me and I'm scared. (Regardless of if it was Samantha or one of the cats...)