Lets just discuss three basic factors which influence disease morbidity:
1. genetics,
2. environmental risk factors,
3. ageing.
Bear in mind this is very simplified explanation; people spend their entire
lives studying these questions and I am trying to use less than 126 lines.
Some diseases are chiefly genetic in origin (although influenced by age
and environment, the disease is only manifested in individuals having the
genetic code for the disease). Other diseases are clearly environmental
and are only expressed in individuals who have had exposure to the agent of
disease. Diseases of ageing are almost always some combination of genetics
(accumulated genetic mistakes or predispositions) and environment (toxins
or other triggers).
Environmental diseases are generally easy to recognize (after the fact);
only those exposed to asbestos develop asbestosis, certain lung cancers
chiefly occur in smokers, etc. Discovering the causative agent provides
the cure; if feeding ferrets in galvanized containers cause zinc poisoning,
get rid of the containers and you prevent the problem.
Genetic diseases are also easy to spot (although far more difficult to
control); if it runs in a family and you can easily disprove an
environmental link, it is usually genetic. Genetic diseases also seem to
have a built in "time of expression;" that is, they seem to click on during
specific physiological stages. Some cancers are manifested during the
rapid growth stage, other diseases occur at the onset of puberty; that sort
of thing. There are few cures for genetic diseases--other than prevention
via controlled breeding. Genetic diseases tend to kill younger age groups,
simply because few survive to be older. But it does depend on the exact
disease; some only manifest themselves in the old..
Non-infectious ageing diseases are nearly always a combination of genetic
and environmental factors, but neither factor is separately stongly
expressed. In diseases of ageing, you may not actually have the genetics
which cause a disease; all you may have is a code which makes it easy for
you to get the disease IF you experience some sort of environmental
trigger. Smoking, for example, is a trigger in certain lung cancers and
similar triggers exist for some breast and cervical cancers. The
environmental part of the equation is nearly always related to time; that
is, the longer the exposure, the greater the risk. That is why second-hand
smoke is so dangerous to non-smokers; each exposure, even if not as
concentrated as in a smoker, STILL increases the risk for those with the
genetic predisposition to specific cancers. The environmental factor
doesn't have to be a substance like tar or radon; stress is not a
substance, yet it is documented in triggering numerous diseases. Also,
your genetic code is replicated every time you grow a new cell in your
body; mistakes not only accumulate over time, but environmental risks can
exacerbate the problem. One other thing; genetic predisposition towards
specific diseases may never be exhibited in wild populations. One of the
more exciting issues in evolutionary medicine is that some of these disease
"predispositions" have actually give an advantage to younger members of the
population, and that it even shows up at all in older individuals as a
disease is accidental because most individuals would die prior to it
becoming a problem. Disease of ageing only kill older individuals, usually
beginning after the physiological peak and then increasing exponentially
over time.
Anyone reading the prior statements should realize the complexities of
unraveling diseases of ageing are great. Just figuring out the causative
factors can take a lifetime. But the realization that diseases of ageing
are typically tied to long term environmental exposure gives us a
tremendous amount of preventative control. You don't HAVE to know the
precise environmental trigger that causes adrenal disease; just control
those you think are probable causes. Does early neutering cause adrenal
disease? Or diet? Or cage stress? Or early maternal separation? Or
lighting periods? Don't know? Then control them all the best you can.
Take adrenal disease for example. If you could find a bulls eye for
adrenal disease, it would be in North America. Now that is very
interesting, because all North American ferrets come from places where
adrenal disease is either infrequent, or only now becoming evident. This
is a strong suggestion to the bright minded that adrenal disease is either
an environmental disease, or one with an environmental trigger. When
looking at the expression of adrenal disease in North America, it is clear
that it doesn't necessarily follow familial lines, so it is probably not an
environmental disease as much as a trigger for some sort of genetic
predisposition. So the key to finding the trigger is in the comparison of
ferret keeping in North America compared to areas where adrenal disease is
very low. What *I* found after making such a comparison are differences in
diet (kibble v. meat scraps and carcasses), lighting (indoor v. outdoor),
caging (open wire cages v. large outdoor pens or cages with dark sleeping
areas), neutering (prior to skeletal growth cessation v. after skeletal
growth cessation if at all), removal from the litter (under 8 weeks v.
after 12 weeks), animal concentration (animals per square foot is higher
because more ferrets are owned per person in North America) and
intellectual stimulation (indoor cage time v. outdoor runs, ferreting,
etc.). Now, maybe a single one of these might cause the increase in
adrenal disease, or some combination, or perhaps something else entirely; I
don't know. The point is, you don't HAVE to know, simply do your best to
reduce as many of them as you can and it is highly probable that you will
nail the environmental trigger for adrenal disease.
In my next post I will discuss specific ways to control these environmental
factors and perhaps, maybe, possibly improve the quality of your ferret's
life. Who knows....
Bob C and 16 MO' Fur de' Butts
[Posted in FML issue 2973]
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