While humans, other primates, and rodents are more prone to getting too
much Vitamin A that is not inclined to be a problem in species that are
descended from animals which regularly ate things high in A such as
livers. This has come up in discussion regularly recently, so I will
keep it short and people can look it up. So ferrets are NOT prone to
problems from A. They do get some problems from too little A and you
can read about some of those in a 2007 study on how Vitamin A may
decrease the symptoms of Canine Distemper:
http://jn.nutrition.org/cgi/content/full/137/8/1916

Some of the things that can go wrong with ferrets when they get too
little Vitamin A include
>Vitamin A deficiency caused anorexia, diarrhea, cataracts, behavioral
>abnormalities, and ultimately death, with or without CDV infection.

(This study may provide some guidance as to amounts, since too much of
anything is bad.)

Taurine shortfall has also been connected to the development of
cataracts in ferrets.

Another way that ferrets (and dogs) differ from humans (other primates,
and rodents) is that we tend to need more Vitamin D than we usually get
according to some recent studies, but if ferrets or dogs get too much
D they can develop medical problems associated with hypercalcemia.

On a different topic: today I learned about the many serious health
problems that using distilled water in place of regular water can
cause. This does not refer to using it as a base for electrolyte powder
for sick ferrets, but for regular use and then the problems can be very
serious (from heart problems, to electrolyte balance ones, to poor bone
mineralization, to GI problems, to anemia, and more):

http://www.who.int/water_sanitation_health/dwq/nutdemineralized.pdf

Sukie (not a vet)

Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html

[Posted in FML 6276]