I had a very interesting question I thought I would share with the
membership as a whole.  The question was, did I think there was some genetic
predisposition in ferrets to make them prone to cancers, tumors, etc., and
if not, how could I explain what seemed to be very high rates of such
diseases when they don't seem to be as high in wild populations of polecats
or feral fitch.
 
(Lets take a moment for each of you to light the tip of your flamethrowers
and take aim on my butt)   First, no matter how good the FML is for us to
learn about ferrets, the FML is a bad place to gather evidence.  Many
incidences are of an anecdotal nature, or based on symtoms rather than
pathology.  Of the thousands of people who read the FML, only a small
portion regularly write, and often those that do are asking for help, so the
incidence of these types of problems are reported out of proportion (more OR
less) to thier actual occurence.  In addition, the FML represents only a
fraction of ferret owners--those who are computer literate (to some degree,
anyway....speaking for myself), and the incidence of specific diseases may
be different in the ferret population as a whole.  In other words, until you
scientifically sample the larger population and prove the FML is
representative of it, the FML cannot be used as a representation of the
larger population.
 
Even if that is true, there still seems to be alot of reported cancers,
pancreatic disease, etc.  in our little FML beasties.  For a moment, let's
assume it to be true.  Problem is, we don't know if it is a trait of
domestication, if it occurs in the ancestral species at the same rate, or if
it is do to inbreeding, founder's effect, or some other problem inherent in
the American breeds.  For all we know, it could be environmental; carpet or
wood-product outgassing, lack of a mineral or protein in the diet, or even
second-hand smoke.  As far as evidence is concerned, it could be any one of
these or hundreds of other factors.  If not these, then what?  Personally, I
suspect something far less sinister for the alleged high rates of cancers
and pancratic disease.  I suspect the same things that effect people; old
age and modern living.
 
Depending on the "expert," ferret life spans vary from 6 to 10 years; I
think it is closer to 8 years on the average, give or take a year or so.
Some time ago, I charted all the death ages I could find of ferrets, taking
data from the FML, friends, some shelters, and other published accounts, and
came up with a bimodal distribution, with one blip at 6-7 years, and the
other blip at 8-9 years.  I suspect the two blips represent sexual
differences, but cannot say for certain because much of the data lacked
sexual orientation.  The blips could also represent large vs small breeders,
specific breeds/linages, environmental conditions, etc.  But because bimodal
age-at-death distributions linked to the sex of the individual are so
common, it is probably what is going on.
 
The aging process is linked to the individual's genetics.  There is an
evolutionary advantage to having limited lifespans, and all biological
systems appear to be limited to a specific length of life correlated to
metabolic rate and size.  Small animals with rapid heart beats live a
shorter time than larger animals with slower heart beats.  Complicating
things is that not all the cells you were borne with follow you to the
grave.  The vast majority of body cells are replaced from time to time.  And
biological systems are not perfect.  Replication mistakes are made all the
time, and the effects are accumulative.  The older you are, the more genetic
damage you have accumulated.  The more accumulated damage you have, the
higher the likelihood of age-related diseases such as pancreatic disease or
cancer.  Bottom line?  Older ferrets have greater incidence of cancers and
pancreatic disease than younger ferrets.
 
Like the Spartans, nature weeds out the old and infirm using disease,
predation or starvation, so cancers and other diseases of the old are not
seen very often in the wild.  We vacinate against the deadly diseases, so
their impact on the little fuzzies is minimal or nonexistant.  So the little
guys get old enough to die of the diseases we have noticed on the FML.  Just
like with humans.  I did a quick search through "Current Contents,"
"Biological Abstracts," and "Science Citations" to se if anything was ever
done comparing the incidence of disease (like cancer and pancreatic
diseases) between species, and found nothing.  (I did find comparisons of
dog and horse breeds, but nothing to indicate what various species of aged
individuals died from.) I did find that, superfically at least, dogs, cats,
cows and horses suffered a far greater variety of diseases, including some
nasty lethal ones, than did our sweet little thangs.
 
In terms of lifestyle, the average acreage a typical ferret needs to live
(at least in a feral state in New Zealand) is about 18 acres per ferret
(This is in marshy land, quite productive, and the requirements seem higher
in more grassy or forested areas).  Even with a centrally placed den, the
amount of running done to hunt, feed offspring, maintain territory, fight
off interlopers, etc., is considerable, and I have had a grave concern for a
long time that ferrets, as a whole, are as under-exercised as their owners.
I haven't had much experience with wild polecats, but wild mink and I have
had an ongoing love affair from time to time, and you would not believe the
difference between a wild mink and a ranch mink in muscle tone alone.  The
few wild polecats I have handled seem to follow the same trend.  Our
domesticated friends lack the physical challenges their wild brethern face
daily.  They are simply out of shape, which increases the risk of many of
the diseases we have noticed in our pets.  Recently released studies have
shown a link between the immune system and exercise; while the study was in
humans, it probably crosses the species line, and is a general mammalian
trait.
 
In short, while it may be ultimately found that the cancers and other
diseases common in ferrets may be genetically linked, there is only
anecdotal evidence at present; no published studies using scientifically-
sound methodology have proven any links other than those of a conjectural
nature.  I think we have learned to maximize the life span of our beasties,
and are seeing the diseases that usually effect individuals of an older age.
Environmental and lifestyle issues complicate the investigation, and must be
accounted for prior to investigating any other factor.  As in humans, the
best course of action may be prevention, with exercise an important part of
the ferret's daily activities.
 
Bob and the 13 Wunning Wascals
[Posted in FML issue 1547]