Cute they may be, but this article in The Guardian thinks that it is not a good idea to keep a fox  as a pet. Others agree. the US foxes.org list these reasons

• They smell as strong as a skunk in close quarters, and although it is theoretically possible to have their scent glands removed, this is not very healthy and will not eliminate the smell of their urine, which is very powerful.
• Foxes need a huge amount of space in which to run.
• Foxes love to dig, and can easily dig out of a yard or through a sofa.
• Foxes are at high risk to carry rabies. In many areas, there is no approved rabies vaccine for foxes; even if you have papers proving your fox has been vaccinated, some states will still have it destroyed and tested if it bites someone.
• Because foxes are at high risk, you MUST get it vaccinated. This can prove very difficult. Veterinarians need a special license to treat wildlife, which many don’t have, because it’s a high-risk, low-reward proposition.
• Lastly, it is very likely that a fox you own as a pet will be very unhappy. Many wild animals become depressed when removed from their natural habitat, and foxes are subject to depression as much as any other animal.