Housing
Ferrets love to get into everything, so if you keep them loose you'll need to make sure they can't hurt themselves or your possessions. They love to steal small (and not so small!) objects and stash them under chairs and behind furniture. They like to chew on spongy, springy things also plastic, which must be kept out of reach or they'll swallow bits which will cause intestinal blockage. Accessible boxes, bags, and trashcans will be crawled in, and houseplants within reach are liable to lose all their dirt to joyful digging. Finally, ferrets may scratch and dig at the carpet. Naturally, these traits vary from one ferret to another, but they're all pretty common. If you're not willing to take the necessary time to protect your property and your pet, a ferret may not be for you.
A metal mesh cage that has a solid metal or preferably plastic bottom is probably the best choice. Pet stores tend to keep ferrets in aquarium enclosures, but they are not recommended as cages. These tanks don't provide enough ventilation at the bottom, and your ferret will feel isolated from what is going on in the room. Most aquariums also aren't nearly big enough. Wood cages aren't recommended because wood soaks up urine and other liquids, so getting the cage really clean is nearly impossible.
If you plan to keep your ferret caged whenever you're not home, and you'll be gone most of the day, a generous cage size is about 2 x 3 feet and 3 feet high with 2 to 3 levels. A second or third ferret could share that size cage. Of course, a nice, big "condo" is even better, especially with lots of levels and hammocks to prevent falls from the top shelf. For trips around town, a shoulder or duffel bag equipped with a litter pan and mesh window works well.
In the cage, you'll want some sort of "bedroom" for your pet. A ferret won't be very happy sleeping on the open floor of a cage, even on (or, more likely, under) a towel or shirt, but any small cardboard box or basket works well as a bedroom. Old T-shirts and sweatshirts make excellent bedding, as long as they aren't too easily chewed to bits. Old towels usually work well too, though some ferrets tend to get their nails caught in the loops. Don't use wood shavings. The bottom of the cage can be covered with sheet vinyl, carpet ramps or bedding.
Other than food, water, a litter pan, bedding, and a bedroom, what you put in your ferret's cage is largely up to you. Enough room to stretch and move around is important, and different levels, ramps, tunnels made from dryer hose or PVC, and so on will probably be appreciated. Hammocks made from old jeans or shirts and a set of metal eyelets are very popular for both napping and playing. Most ferrets get bored easily when caged and sleep much of the time, so they probably won't get a whole lot of use out of toys; they'd really rather be out playing. Just be sure nothing you put in your ferret's cage could hurt him, whether by catching a toe, being swallowed, or some other way.
Also be sure your cage door fastens securely, perhaps even with alligator clips, because ferrets can be very determined and rather intelligent escape artists. Velcro works well for fastening down litter pans or some bowls; and clothespins and small bungee cords can be enormously handy for holding all kinds of things down, up, or closed. You need to keep an eye on any Velcro, plastic, or rubber that your ferret has access to. If they chew on it, they can develop blockages and die. As soon as you see any on these things fraying or breaking, throw them out and replace them with something more durable.
Diet
Ferrets must eat frequently due to their unusual anatomy, therefore, constant availability of food and water is important for ferrets, especially in warm weather. It is particularly essential for pregnant, old, or chronically ill pets, and for growing ferrets. Ferrets that fast more than six hours will become irritable and much more likely to bite.
Ferrets require a high-calorie, high-protein, low-fiber diet. These requirements may be met by commercial ferret diets. Dog food of any kind in (is) inadequate for growth and good health in ferrets. Even the best quality premium dog food will not support ferret growth or reproduction.
Grocery store brands of dry cat food are commonly coated with animal fat, making them more palatable to ferrets, but feeding your ferret a steady diet of these cheaper brands can produce health hazards. Even though the product ingredients may be listed as 30 to 35% protein, if the main source of this protein is ground yellow corn, your ferret will not get the nutrition he needs to stay healthy. Veterinarians or pet shops premium brands contain 30 to 35% protein, but the primary ingredient is usually poultry, red meat meal, or meat by-products which meet a ferrets nutritional needs. The ferret will eat less of the premium brand b/c it is meeting all of their needs, thus in the long run, it is more cost effective to buy the premium brand over the grocery store one. Check the ingredients of the brands you buy.
Ferrets require a higher caloric diet, and their main source of calories should be from fat. Adding fat to cheaper foods to increase the caloric concentration will give mature animals shinier coats temporarily. However, because ferrets eat to meet their caloric requirement, they eat less of the higher fat diet and soon become deficient of protein and other essential nutrients. The coat then becomes thin and bristly. Growing kits will be stunted or die, adults will be thin, reproduction will fail, and some animals will develop diseases or ulcers.
Housed under natural light conditions, ferrets will eat more in the fall and will become noticeably fatter (adding as much as 40% or more to their weight). This is a normal, healthy response and is not a cause for concern. They will, in turn, reduce their intake in the spring and lose the excess weight. Obesity is rarely a problem in ferrets unless they are fed large quantities of high fat snack foods daily, in addition to their regular diet. The best way to return obese pets to a more normal body weight is to reduce their snack food consumption. Since Ferrets tend to rest their feet on the water bowls when they drink, a heavy crock is the ideal water container. *This may just be my belief, but… A large water bottle is the best water container. This is b/c often a ferret will dig in their food and get it into the water bowl, not only is this wasting food, but it is contaminating the water, so then you have to change it more often. Also, if they get wet from dunking their heads in the water (which they will do!), they could feasibly get sick.
Behavior
Ferrets are very playful, with each other and with you, and they don't lose much of that playfulness as they get older. A ferret -- or better, two or more -- can be a very entertaining companion. They are very inquisitive and remarkably determined, which is part of their charm but can also be a bit of a bother. They are friendly, and they do recognize their owners. Though some are slower about showing this than others. Ferrets can be trained to use a litter box and to do tricks, and most of them love to go places with you, riding on a shoulder or in a bag. They sleep a lot, and they don't particularly mind staying in small places (a cage, for instance, or a shoulder bag) temporarily, although they need to run around and play for at least a couple of hours a day. A "single" ferret won't be terribly lonely, although the fun of watching two or three playing together is easily worth the small extra trouble. Barring accidents, ferrets typically live 7-12 years. Ferrets have lots of good points as pets, but there are some negatives as well. Like kittens and puppies, they require a lot of care and training at first. They're "higher maintenance" than cats; they'll take more of your time and attention. Ferrets have their own distinct scent, which bothers some people, and many of them aren't quite as good about litter pans as cats are. Although most ferrets get along reasonably well with cats and dogs, it's not guaranteed, so if you have large, aggressive pets (particularly dogs of breeds commonly used for hunting), keep that in mind. Remember to introduce all new animals slowly to the resident pet(s). and as always, keep a watchful eye for any aggressiveness. Ferrets roughhouse and will play like this to determine dominance. However, if the “loser” seems to be running away, not coming back for more, then they are fighting. Occasionally they will both scream, so beware that the screamer may be the aggressor.