We are starting to turn a solid play structure into a chicken coop, run and storage. The bottom level of the structure was/is a children's sandbox and had become a giant litter box for outdoor cats. In preparing it for chicken use (as an extension of the outdoor run), do we need to remove ALL cat poop? Alternatively, if we remove 1-2 inches of sand and cat coop and add 2 inches of pine wood shavings, will this be okay for the chickens? And, is dog poop dangerous for chickens? Thanks!