I have a medium/big dog. He's messed up my hardwood floor (full of scratches, and also big dents as his toys and bones etc fall from the bed and whatnot), scratched my fullwooden front door to shit and even tore some of my wallpaper off as a pup. Luckily it's my place so I don't have to explain this shit to anyone, just gotta renovate before I move out and rent this to someone.
Then again, kids do the same kind of damage. Depends totally on the dog, my dog IS allowed on the sofa, or the bed etc.. but some little rat couldn't even do damage if it tried.