From:
Sukie Crandall
Date: 2001-08-30 12:53:00 UTC
Subject: Re: [Ferret-Health-list] Re: adrenal problems
Like Lisa Leidig our numbers have been lower (47% over 19 years) than
what Dr. Weiss says is to be expected, but it makes sense that only
by having someone who knows both veterinary medicine and research
methods/math compiling a truly large number of ferrets --with their
situations tightly defined -- can the reality be known. Mike's higher
numbers and LL's and our's lower would settle to something in the
middle -- a display that likely would repeat itself many times here.
There are several things that interest me about adrenal disease:
First is that clumping multiple adrenal based diseases together might
cause a result that *might* prove inadvertently misleading down the
line. It would be interesting to be able to see if that would prove
a possible problem.
Second is that we really do not know how many silent cases there are.
Take a human example: it used to be thought that a slipped disc on
an x-ray was a big deal, then later it was found out that only about
25% of slipped discs in humans ever cause problems. We have had
ferrets (2, if memory serves) who, on necropsy, turned out to have
adrenal neoplasias that had never caused symptoms. This leads to the
question of whether those were simply below the threshold for
producing symptoms so had not, yet, done so though they would have,
or if some few adrenal growths can remain forever silent and
asymptomatic. (We have also had two with fur loss who had
non-adrenal-growth causes.)
Third is that new pockets of adrenal diseases lead to many questions.
They could reflect just diagnostic changes, but when a person sees a
pocket like the one reported in Australia then one has to wonder if
there could be possible other factors such as viral exposure that
might make those which fit certain categories more likely to develop
such problems. If there are such factors then flux would be expected,
and so might an increase in percentages and range as such a viral
component became more wide-spread. (Remember though, that folks tend
to be more likely to diagnose what they expect so rate changes over a
population can also just say that ferret-people and ferrets' vets
look more for adrenal growths in places and ages where they did not
look before, which could be no more than a natural result of the
ferret-education of the general vet population improving. Yes, it
sounds weird, but rate changes with more adrenal diagnoses could be a
good sign that more vets know more about ferrets than in the past.)
Fourth is that I know that our number of adrenal growths have
increased here at home -- from in the low 30th percentile a few years
ago to a figure now in the upper 40th percentile. Meanwhile, the
ages of those affected have decreased. For a long time we'd never
had one with adrenal symptoms below 7 years old, then for a long time
we'd never had one below 5, now we've never had one below 4. (Unless
a vet age guesstimate on one was wrong.) I certainly have heard from
reputable people who have encountered younger ones, and who have said
that they have observed the ages of those affected in their groups
decreasing. Personal observations or clumps are not necessarily real
over a population, though. Remember that for the entire 19 years
here --with only one exception -- all have been early neuters. This
leaves questions such as: "Is the rate of adrenal disease actually
increasing (if so, in which subset(s) of adrenal disease?) or is this
an illusion?" and "Is the age of onset decreasing, or is this an
illusion?" If -- in a real study by those with the expertise to do
such studies properly -- it turns out that either or both is true
then there is the big question, "WHY?", which is likely to be one
heck of a hard thing to answer unless serendipity steps in.
Fifth is whether neutering makes any difference in rate and if age at
neutering makes any difference. There was study done in the
Netherlands which showed that adrenal diseases certainly are present
there, but -- having had mathematicians who specialize in studies
look at the results -- the hint that there MIGHT be a pattern is
exactly that, a hint which may or may not pan out on further study.
Anyway, I guess that the upshot is still what it has been: adrenal
growths present more questions than answers in things like rates and
variations(?) in rates, so we are left with what mostly amounts to a
LACK of hard information on the many aspects including "whys" and
"ifs" as well as a number of interesting hypotheses and personal
observations that may or may not pan out under real study. Meanwhile,
we have ways to treat many of the forms of adrenally-based growths,
and many folks use precautions that may or may not make any
difference at all (for example, we provide real darkness for our
ferrets for a number of hours every day which might make no
difference at all but is do-able and safe). Oh, and one more
"meanwhile": we can all continue to give to those places which fund
well-designed studies such as veterinary schools, some Comparative
Mammalian Medicine university departments (as at MIT), some clinics,
and the Morris Animal Foundation.