Physically, ferrets are similar to cats. The male ferret, called a hob, can weigh up to 4 lb (2 kg). The female, known as a jill, can weigh up to 2.5 lb (1.2 kg). Ferrets come in a range of colors, but common variations include white with pink eyes, sable, cinnamon, and chocolate. White patches on the throat or toes are common. A ferret’s coat will change color and density with the season; it will darken and thicken in winter, then lighten and shed in summer. Ferrets generally reach full size at 5 to 6 months of age and are considered adults at 1 year. The typical life span is 6 to 10 years, but many life spans are shortened due to accidents or illness ( see Table: Ferrets at a Glance Ferrets at a Glance ).
Ferrets have less of the musky smell that is characteristic of this family of animals if the gonads are removed early in life. The anal scent glands are also usually removed at the same time. Many ferrets have these surgeries performed before you buy them. If not, it is important to have a female ferret spayed before she goes into heat for the first time to prevent life-threatening consequences such as the development of hyperadrenocorticism.
Many adult ferrets have a large spleen due to increased production of red blood cells. Enlarged spleens are considered benign unless a ferret shows signs of illness, but have a veterinarian check to make sure the enlarged spleen is not a problem.