[2 part post combined.  BIG]
 
Karen, thank you so much for posting details about that study, "Correlation
between age at neutering and age at onset of hyperadrenocorticism in
ferrets", by Nico J. Shoemaker, DVM, DAVBP, Marielle Schuurmans, DVM,
Hanneke Moorman, DVM, and J. (Sjeng) T. Lumeij, DVM, PhD, DABVP.
 
One thing that would be useful to know would how often vets there look for
the disorder.  Historically, I recall areas which HAD thought that they had
low rates find more once people were more likely to consider it among the
possible dz group.  Given some had found it, though, one would expect that
those particular vets were open to the possibility and even those must have
found low number with a 55 in ten thousand rate, with a possible rate of
110 in ten thousand given the ones whose owners refused the medical care --
which leads also to the question of how many don't receive medical care
when ill, a problem which can skew numbers if too high or off-centered.
 
The on-set age aspect is a very interesting take on the topic, but the
slush factor of plus or minus 1.8 years is just plain huge, and the number
of affected ferrets was rather low so the linear aspect mentioned is
certainly something I'd want to see duplicated in a larger study --
preferably of animals more likely to be in the affected age ranges.
 
>Their conclusion is that earlier neutering correlates with earlier disease
>onset, while neutering later in life correlates with later disease onset.
 
Note that the typical late neutering difference of 6 months vs.  earlier,
given the slush factor, MIGHT not make a huge difference if the rates of
eventual onset aren't a different pattern ("age at diagnosis was 3.5 years
(mean 3.5 +/- 1.8 years, range 0.5 to 8 years") and if this pattern affects
younger neuters WITHOUT a change in rate.  (There are reasons to prefer
safer modes of neutering, though, no matter what is found.)
 
It WOULD be interesting (actually ESSENTIAL) to compare rates for early
neuters vs. older neuters.  That is still lacking.  Note the neutering age
range for the neuters given.  Now, this MIGHT have something to do with the
low rates of adrenal disease there, or other variables might be involved.
That has NOT been investigated in this study so be careful to not read it
in.  It is possibly suggestive on that score but that's it.  IF large rate
differences between early vs.  late neuters could be found in a large
comprehensive study by some vets, then that taken in conjunction with this
study could be very enlightening.  (HINT, HINT!)
 
The median ages could show a possible difficulty given what the vets found
as the ages likely for adrenal disease on-sets ("Median age of neutered
ferrets was 3 years.  Median age of intact ferrets was 1 year."), and this
was especially true for the intact ferrets.  Median is the middle number in
a series, mean is average, mode is the most common number.  Obviously, if
the middle age in the series for intact ferrets was only a one year they
were largely below the ages where adrenal disease occurs.  The median age
for the neutered ferrets also contains a large number of animals of ages
too low to be ill with the problem.  How many people consider kits in their
numbers for a middle-age to old age health problem?
 
Now, given that the rate diagnosed is lower there than here there are
multiple possible causes: the vets might not look for it as much, vet care
might be less sought to a degree that it throws off numbers, ages may have
included too many animals too young to get the illness, the neutering
differences, other variables.  A supportive study is needed, but this is
an essential and important first step.  The supportive study would not
necessarily have to be a duplicating one.  If a large comprehensive study
by vets of late vs.  early neuters found that there is large difference
between rates for these two groups AND if it found a similar incidence of
this adrenal disease in the late neuters as they found, then that suggests
that the lower over-all rate there might simply reflect the absence of
early neuters.  If the difference is not large enough to account for such a
difference in rates, or if we have more cases of this adrenal problem among
late neuters in other areas then there are some very important variables
affecting rates which have to be found.  (At least that's how it seems to
me; does that make sense to you?)
 
I am very GLAD that there is finally a study out there, and I applaud the
vets involved for putting in the huge effort it took.  My problem is that
while there may be interesting direction here there are also so many things
which could pose problems that I'd rather see a larger study which
concentrates on the ages most likely to be affected, but asks some of the
excellent questions (such as the neutering ages in relation to onset ages)
questions asked by the vets in this study.  Shelters have often pointed out
that even among whole ferrets they see adrenal growths, but at only very
old ages.  I'd like to know if the difference between early vs.  6 month
neuters really makes a difference, and if later neuter rates are consistent
in other areas which see more adrenal disease.
 
(This leads to wondering what happened with that dietician who was looking
at phytoestrogens and ferrets.  There are a lot of questions existing with
human phytoestrogen intake including if these might worsen some types of
growth if certain types of phytoestrogens are taken once growths start yet
be possibly protective if they are consumed throughout early life.  Why do
I mention this?  Perhaps they might be useful for ferrets if taken in the
first three to four years of life ***IF*** some of the hypotheses which are
ONLY hypotheses at this time bear out under study.)
 
Note that I am not an expert by any means so adjust your opinion of my
comments accordingly, and that I have not yet seen a copy of this study so
would appreciate one since some of what I mention above may be tackled
within it.
[Posted in FML issue 2943]