Enlarged nodes may be from lymphoma/lymphosarcoma OR may be from systemic
infection.  The thing to do is to have the vet remove a node and have a
biopsy done, sending the node to a ferret-knowledgeable pathologist.
 
Infection and lympho have DIFFERENT -- opposite in some ways -- treatments.
 
If it is lympho, how old is the ferret?  Those is their prime (2 to 4
years) sometimes (about 10% of the time) get remissions with specific
chemo protocols.  For older ferrets it often makes more sense to go
with Prednisone or Prednisolone which is a lighter approach that
reduces symptoms and slows the growth.  Since these meds also have
immuno-suppressant actions you need to find first through that removed
node if what you are seeing really is lympho.
 
BTW, blood tests are NOT diagnostic for lympho.  The originator of that
hypothesis found that out through research but third parties have
sometimes continued thinking that the idea was a fact rather than a
hypothesis.
 
Here is a resource which may help you.  Open the Reference Shelf which is
within the Files Section of the Ferret Health List
http://www.smartgroups.com/vault/ferrethealth
and you'll find that there is a list in there of compounding pharmacies
(many of which mail meds) which are used to helping ferrets.
 
The FHL would also be a good place to ask your questions
http://www.smartgroups.com/groups/ferrethealth
and the FHL Archives
http://fhl.sonic-weasel.org/
will provide you with a number of past expert answers in a jiffy.
[Posted in FML issue 3927]