The ferret is a member of the weasel family. There are two types of ferrets: domestic and black-footed. Domestic ferrets are descendants of the European polecat, which was found throughout Europe in ancient times. Black-footed ferrets, who are native to western North America, are extremely rare and are currently classified as an endangered species.

Domestic ferrets vary in coat color—ranging from dark to light shades. They are generally 17 to 24 inches long, with females usually shorter than males. Ferrets normally weigh between one and five-and-a-half pounds.

Ferrets have short digestive cycles, which prevents them from obtaining adequate nutrition from vegetable proteins. Therefore, a primary requirement in their diets is animal protein.

The length of gestation for a ferret is approximately 42 days. The average litter size ranges from six to nine kits. Born without fur, kits begin to develop fur by nine days of age. They possess a full coat within four or five weeks. At six to eight weeks, the kits are weaned. The life span of a domesticated ferret ranges from five to six years in the laboratory and up to ten years as a companion animal.