One of the most important thing you can do as a responsible ferret owner is to ferret proof your house. Ferrets will squeeze into the smallest places (if the their head will fit, the rest will follow). For example, my ferret Abby (she weighs about 1 lb) likes to squeeze underneath doorways. One day I got up and she tried to squeeze underneath a doorway and was STUCK, I don't know how long. I installed strips along the bottom of doorway to prevent this from happening again.
When I moved into my current house, before the clothes dryer was installed, she escaped through the dryer exhaust. She proceeded to the neighbors back door, and a friendly ferret that she is, the neighbors picked her up, came over and asked if I had a ferret. I did not know even know she was GONE.
Here's an article about household dangers