Q: "I was just wondering if I should open the window blinds for natural
light for them or keep it closed during the day....Is it really better to
put something over the cages and would that be during the day also?"
 
A: Not unless you have a problem with daylight during the night.
 
These are really two questions.  The first question is actually one
about the relationship between the ferret's biorhythm and various ferret
diseases.  In a technical sense, photoperiodism refers to plants and
biorhythm to animals, although in many circumstances people refer to the
daily light/dark cycle as it relates to animals as a photoperiodic cycle
and the total phenomenon as photoperiodism.  Call it nit picking, but in
referring to animals, it is better to use the terms biorhythm and
light/dark cycles.  In ferrets, the question at hand is, does a disruption
of the normal light/dark cycles cause environmental disease, especially of
the adrenals?
 
Ferrets, like cats and dogs, are peculiar in that as domesticated animals,
they do not typically follow their evolutionary biorhythmic pattern.  In
other words, while most polecats are classified as either nocturnal (that
is, active at night) or crepescular (active at dusk or twilight), ferrets
can be active ANY time of the day.  In fact, they seem to adjust their
activity patterns to those of their owners.  Part of this is simple; have
someone wake you up at three in the morning half of your life and your body
adapts to the sleeping disruption.  Ferret owners do about the same thing
when they come home and wake up little ferret to play.  I doubt if this is
caused by domestication because feral ferrets follow the polecat pattern.
It is probably, at least in ferrets, due to the ferret adapting itself to
the human activity pattern.
 
Not just activity patterns are controlled by light/dark cycles, but also
physiological functions, including yearly weight gain and loss, shedding,
heat and rut cycles, and even aggressive tendencies.  In these cases, the
Zeitgeber (that is, the "time giver;" the environmental trigger which
controls biorhythmic patterns) is not just the presence of light, but of
light DURATION.  This is well known and exploited to get ferrets to enter
heat anytime during the year, simply by manipulating the "day length."  The
biochemistry is complicated and still somewhat controversial, but the links
are well documented.
 
The basic idea is that living under normal human artificial lighting
disrupts the physiological Zeitgeber.  It is this disruption which may
cause physiological changes which could lead to environmental diseases.
There is some recent work which suggests adrenal disease might be linked
to human home lighting practices which either over stimulate the adrenal
glands (or possibly weaken the immune system) increasing the chances for
cancers.  In either case, the result is adrenal disease.  While I find
the research to be promising, the relationships are far from proven.
 
The second question is not about the physiological needs of the ferret (as
explained above) but about the PSYCHOLOGICAL needs of the ferret.  Ferrets
are animals which actively seek out darkened sleeping spaces, including
(but not limited to) couch and chair interiors, holes, interior of cabinets
and dressers, and even under blankets.  This is a deep rooted instinct and
while I have seen plenty of ferrets which will fall asleep just about
anywhere, MOST retire to a dark and quiet place to slumber.  Darkness may
not be the only factor here, but also touch.  It is possible the ferret
has a psychological need to sleep in tight and enclosed spaces.  I have
wondered this when watching a dozen ferrets trying to sleep in a plastic
bag, or ignoring the large dark box to sleep under a sweatshirt or in a
pants leg.  This is just anecdotal evidence, but I have calmed many a
frightened ferret simply by covering them with a dark towel and holding
them quietly and firmly.  I have also noticed behavioral improvements in
ferrets after covering a large portion of their cage with a blanket, or
by providing them with a nesting box within their cage.  I know of one
instance where a serious biter almost immediately stopped biting when
given a nesting box.  It is possible these two phenomenon are so closely
intertwined that one cannot be effectively separated from the other.  For
example, you might think the reason the biting stopped was because the
ferret's psychological needs were met, but it could be that the light was
triggering an over stimulation of adrenal hormones, increasing nervousness
and aggressiveness.  Since this type of research is essentially in its
infancy, we have to wait to find out.
 
As for what you can do, covering large portions of the cage will not change
how room lighting impacts the biorhythmic Zeitgeber.  More important would
be LENGTH of the light and since most homes have subdued lighting at night
(it only seems bright because of the darkness), it is probably not as
much of a problem as might be expected.  You can minimize the problem by
replacing your bulbs with low wattage bulbs, say 60 watters and turning
them off as much as possible.  Open your drapes to admit natural light
during the day (the idea is the relationship between light and dark, NOT
when the ferret is actually awake).  Give the ferrets a small darkened area
to sleep in (a nesting box).  Will these steps help?  I honestly don't know
if they will prevent adrenal disease or not, but can they hurt?  If they
just make the ferret psychologically happier, then they have worked.  For
the rest, we have to wait for the research.
 
Bob C and 16 MO' Lightning Lovers
[Posted in FML issue 3015]