BTW, the ferrets are from a exceedingly large farm, the largest,
actually.  The chances of them being related are minimal, but note that
is taken into account as a possibility in
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to which I had referred people.  I've been up-front about what isn't
known as well as what can be best to just keep in the backs of people's
minds in case a problem in one of their ferrets needs investigating in
the future.  I've also said what the vets suspect here.
 
Leanne, Thanks for the info.  We found that stuff on the known cause,
too, and also found mention of the alternative hypothesis for some cases.
I have not implicated any single food (You mentioned the Pretty Bird
food, but the one of our's who likes that the best is not among those
2 found with stones (but he hasn't been checked yet just as another
without symptoms has also been waiting for the vets' decisions after
the pathology so they might still be imaged just in case).  I've just
repeated what the treating and consulting vets all said: that they
suspect a dietary cause (but note that the bladder deformity which
existed in Hilbert did predispose him to stones of any type and we were
just lucky in getting marvelous vet care because this deformity is rare
but usually fatal).
 
Notice also that what I was doing was that I was making people aware that
there can be an upper protein limit just as there is a lower limit in a
domestic situation for optimal health but we just do NOT know what the
range that is best for most ferrets is yet -- not what is the optimal
level and not what is outside that range, nor do we know how much any
range may vary among individuals.  Thought of that way (and I wish I'd
realized the possibility beforehand, but even doing that wouldn't have
helped because there isn't enough data to know what is optimal) it isn't
by any means exactly a radical concept that there can be upper and lower
levels at which problems can occur, nor that there can be variation among
individuals in that regard.  It also doesn't say anything about where
those limits are at this point, nor where the optimal protein amount is,
nor if broken down proteins may warrant more investigation in ferrets.
It's like so many other things so often thought about and tried: we each
just try our best (which we did) but some things just can only be found
in practice and how common those things are and the other nuances which
eventually teach us all are only learned over time with sharing.  There
are far more unknowns than knowns involved, but it does no harm (but may
save some ferrets if trouble arises) if people are aware of possibilities
should the symptoms arise in their ferrets or should actual stones be
found and the question come up whether or not to have pathology done on
them (with the correct answer being YES).
 
Mary, thanks for that info.  I had no idea that cystine was important
in skin more than elsewhere and in detoxification (of what type of
compound?).  I notice you quote that over a certain amount one form
poses oxidation problems, nerve damage, loss of zinc and copper in rats.
They would have less ability to deal with high levels than members of
Carnivora, of course.  Also, that study might have had the type of
proteins in combination amounts that themselves are important to take in
to consideration.  It is interesting stuff, though, and a reminder that
nothing is all good nor all bad.  I do NOT know which forms would have
been most common in any of the foods.
 
Mostly, time and continued follow-ups are what will be the teachers for
our guys right now.  Those will tell what we need to do next, if
anything.
 
As Mary wrote:
>My thoughts go along these lines.  When using a more obscure amino acid,
>or one in which deficiencies have not yet been defined, you get into the
>dilemma of which other supplements to use to balance the whole thing
>out.  If you don't maintain that delicate balance of vitamins, minerals,
>and supplements you can get into trouble.  Now these findings are for
>humans, so it's important to know why the makers of these ferret foods
>put certain ingredients in there in the first place.
 
Yes, balance, limits, and optimal levels are things on which more and
more is learned over time and then once the data are in the things we try
and the choices for purchases become safer and more optimal.  Sharing
info facilitates that process.
[Posted in FML issue 4570]