According to my vet, onions are associated with being a trigger for
hemolytic anemia in ferrets as well as other animals.  Hemolytic anemia is
an auto-immune disease, where the red blood cells start self destructing.
This can cause jaundice, because as the red cells burst open, they release
the pigment into the surrounding tissue.
 
I lost a ferret to hemolytic anemia just a few months ago, although in
that case it had nothing to do with onions.  Another trigger is Amoxi, and
we suspect it as the culprit in this case.  Please note that I use the word
'trigger' and not cause.  This is because the onions or Amoxi or whatever
else can be consumed by most ferrets without a problem.  It is just
occasionally they will trigger the immune system to start malfunctioning.
Although larger animals can frequently be successfully treated for this
condition, because of their small size and high metabolic rate, it is hard
to save a ferret with this problem.
 
I am not a vet, and I am only trying to relay what my vet explained to
me, so I apologize in advance if it is not 100% technically correct.  If
anyone with training in the area cares to comment on this subject, I would
appreciate hearing their remarks, so that I might better understand the
problem.
 
Danee DeVore
[Posted in FML issue 2900]