These coat changes, like weight change, happen because of the fluctuation in day length, which triggers hormones, including estrogen, that regulate the growth or loss of hair, Fox says. For example, leaving lights on at night will lengthen the ferret's day and can cause the animal to keep the same coat for more than one season. He says that this is not a medical problem, but some ferret fanciers and experts suggest that manipulating a ferret's exposure to light may be an important aspect of the animal's long-term health. Mike Janke, ferret owner and secretary of the South Florida Ferret Club and Rescue, has been gathering information on the topic for more than a year. If the gland is over-stimulated and begins to function abnormally, then the ferret develops adrenal gland disease, common in ferrets four years old or older.
Symptoms are grossly exaggerated seasonal changes, such as extreme hair loss.
The possible root of this problem is simple, Wood says. The biological clock of Earth is the sun, but people don't live by the sun anymore. Ferrets live by whatever schedule their owners adopt. This can include many consecutive hours of exposure to light that would not normally occur. I do this myself when I work at the computer in the evenings and light a room that would otherwise be dark.