Spruce Chips???

LTPM, where are you getting your information? What do you mean pine "cuz" it's "treated?" The problem with pine is the phenols that are given off. Spruce is also a softwood, like pine, and probably has the same issue with phenols. I think more investigation needs to be done to determine if spruce is more like cedar or more like pine in the level and type of phenols. I would consider it suspect until proven otherwise. IF you decide to use it, like pine, I would make sure it is KILN-DRIED and doesn't not have a heavy pine or spruce scent to it. If it 'smells good' that's a clue that it is not good for your guinea pigs.

Let's please stick to facts when posting advice. If you are really not sure, don't guess. You could be harming someone else's animals.