I know that this has been discussed in the Ferret Health List so you
should be able to find it in the FHL Complete Archives.
 
These should help:
 
http://fhl.sonic-weasel.org/browse.php?msg=YG356
 
http://fhl.sonic-weasel.org/browse.php?msg=YG5562
 
I have found a certain conversation to become circular.  If folks won't
check the resources and if folks assume that anyone who has mentioned
some ferrets in their lives who have gotten along perfectly well with
rabbits, mice, rats, chinchillas, etc.  can't possibly be telling the
truth, then what is the point of repeating just because they haven't run
into it themselves?  We know that there is stock that hunts readily, but
that isn't a universal situation.  If it is assumed that even though
after hundreds of years with ferrets in the U.S.  that they will still go
feral when they simply haven't, then what is the point?  Heck, I could
release a pile of chihuahuas around here assuming that since we have
coyotes in our part of New Jersey that other canids would easily go
feral, but I doubt we'd get colonies of that little dog.  Domestic
species can vary widely and certainly ecology does so why assume that
the stock or conditions here well enough match those elsewhere?
Variation is prevalent.  The conversation was useful while new folks
were being introduced to information which is useful for them, but for
my taste (and my choice whether to participate) it is bogging down right
now with the same old things.
 
Lumps: Terry take the ferret to a vet to be checked for things that
inflame nodes such as systemic infections or lymphoma.  The only way
to know if it is lymphoma is to do a biopsy.  Blood tests are not
diagnostic; there had been a hypothesis that it could be but that has
been disproven.  In a healthy ferret who is never-the-less overweight
such lumps can also be fat, but your vet needs to check.  It is hard
long distance to know what a person means in a description but this
grouping: enlarged nodes or fat around the nodes is among the things
for the vet to check.
[Posted in FML issue 4027]