Foxes, like many other species of wildlife, are adaptable creatures and can find ways to live in urban areas. If they can find sources of food, water, and shelter against the elements and predators...they will try to live there. It isn't uncommon for foxes to live in residential areas. They will feed on many different plant and animal sources, but rabbits, mice, and voles typically make up a substantial portion of their diet. The fox is not likely to bother the puppy. But to help assure that your puppy stays safe, as with any young pet, it is best to monitor him/her while outside. You can find more information about foxes at:
http://web.extension.uiuc.edu/wildlife/directory_show.cfm?species=redfox And if you have more questions, you can e-mail me at lasimmon@illinois.edu