I have used carefresh for many years in all kinds of animals cages. I have had prairie dogs in it, mice, rats, guinea pigs, rabbits, even lizards once in a while. I would rather that because it is recycled. I'm not killing more trees and because you dont know what the shavings are treated with I dont find them as safe. Even if it is from a tree that isnt known to cause respiratory problems, I believe they are supposed to treat the wood with chemicals to kill any mildew, mold, or insects. Has anyone else heard this?