The first 12 weeks
When ferrets are first born, they are extremely small, about 2 inches long (5 centimeters) and weighing less than half an ounce (14 grams). They are born deaf, blind, and without any teeth. They have very fine, white hair, which will develop into their adult coloring within 3 weeks.
Kits are completely dependent on their mom until 3 weeks of age, when they start to open their eyes, their ear canals unseal, and their teeth grow in. At 4 weeks, they start to play with each other and at 6 weeks, they can be weaned and start eating solid food.
While ferret kits are fairly independent at 6 weeks, they still need to learn more socialization and survival skills from their mother. Kits should not be removed from their mother’s care until they are at least 8 weeks old (but preferably stay with their mother until they are 10-12 weeks of age).
Some vets believe that the shorter lifespan of American ferrets is a result of the way large commercial breeders treat ferrets during their first 12 weeks. Commercial breeders usually spay or neuter ferrets well before they are sexually mature, around 4–6 weeks of age. They also usually sell ferrets at 8 weeks old, removing them from their mothers too early. Both of these practices may lead to a shorter lifespan.
The first year
Ferrets become sexually mature very quickly. Female ferrets are typically ready to mate by 8 months of age and male ferrets by 10 months. They are considered adolescents until they are 1 year old.
Ferrets tend to be nippy in their first year, like young puppies. In the first year, you will need to spend the most time training your ferret not to bite.
Adolescent ferrets are extremely active and need more out-of-cage time. They tend to play for hours each day, interspersed with deep sleeping.
These are the prime years of an adult ferret’s life. They are active and tend to be at their healthiest. However, young ferrets can still develop serious illnesses, including lymphoma, insulinoma, and adrenal disease. Thus, ferrets of all ages should go to the vet regularly for check ups.
You may notice that your ferret’s coat is changing color! This is because ferrets go through two coat changes a year (typically in the summer and winter) and their coat color can change each time. For example, the shape of a ferret’s mask may change or they may become darker or lighter.
In addition to coat changes, ferrets will also lose weight in the summer and gain weight in the winter.
At this point, a ferret is considered elderly. You may even notice your ferret starting to get gray hairs, just like a human!
Older ferrets will be less active, sleeping more often and playing less energetically. They may also lose weight and are more likely to develop serious illnesses. In these later years, the weight changes between seasons may not vary as much as they did when the ferret was younger.
Like with older humans, you should take extra care of an older ferret. They should go to a vet more often, have blood work and other tests done regularly to ensure they are healthy, and you should ensure that their quality of life is the best you can provide. Even though older ferrets are less active, they still want stimulating toys, fun activities, and attention from you!