The ferret (Mustela putorius furo) is the domesticated form of
the European polecat, a mammal belonging to the same genus as the
weasel, Mustela, in the family Mustelidae.
The name "ferret" is derived from the Latin furittus, meaning
"little thief", a likely reference to the common ferret penchant for
secreting away small items.
Ferrets have a typical mustelid body-shape, being long and slender. Their average length is about 50 cm (20 in) including a 13 cm (5.1 in) tail. They weigh between 0.7 and 2.0 kg (1.5 and 4.4 lb) and are sexually dimorphic as the males are substantially larger than females. The average gestation period is 42 days and females may have two or three litters each year. The litter size is usually between three and seven kits which are weaned after three to six weeks and become independent at three months. Their average life span is 7 to 10 years.
Ferrets spend 14–18 hours a day asleep and are most active around the hours of dawn and dusk, meaning they are crepuscular. If they are caged, they should be taken out daily to exercise and satisfy their curiosity; they need at least an hour and a place to play. Unlike their polecat ancestors, which are solitary animals, most ferrets will live happily in social groups. They are territorial, like to burrow, and prefer to sleep in an enclosed area. As with skunks, ferrets can release their anal gland secretions when startled or scared, but the smell is much less potent and dissipates rapidly.
Ferrets are obligate carnivores. The natural diet of their wild ancestors consisted of whole small prey, including meat, organs, bones, skin, feathers, and fur. Ferrets have short digestive systems and a quick metabolism, so they need to eat frequently. Prepared dry foods consisting almost entirely of meat provide the most nutritional value for domesticated ferrets.
Ferrets are known to suffer from several distinct health problems. Among the most common are cancers affecting the adrenal glands, pancreas, and lymphatic system. Viral diseases include canine distemper and influenza. Health problems can occur in unspayed females when not being used for breeding.
There are four basic colors. The sable (including chocolate and dark brown), albino, dark eyed white (DEW, also known as black eyed white or BEW), and silver. All the other colors of a ferret are variations on one of these four categories.
Selling, distributing and breeding ferrets in countries such as New Zealand is illegal. In Australia, United States, and other countries restrictions apply.