When I have a sick ferret I also give a small amount to the healthy ferrets as a treat, this way they are used to the taste. For this reason you need to make his cage as comfortable as possible. A ferret cage should be 36 X 24 X 18 or larger . A solid bottom is better on the ferrets little feet, however most cages have a wire bottom. If your cage does have a wire bottom there are many ways to make it more comfortable for your ferret.
Some people cover the bottom with rug, but it is harder to keep clean and pleasant smelling.
I cover the bottom of my solid and wire bottom cages with sheets, it takes 2 sheets to make it warm and comfy. Sheets can easily be taken out and washed once a week to keep the cage clean. If you don't have any old sheets lying around blankets or towels can also be used. It is very important to remember to check your new ferrets bedding because some ferrets will chew holes through their bedding and this can cause intestinal blockage requiring surgery . If you find that your ferret does chew his bedding try to find something he will not chew.