Many things cause lethargy (ditto hind leg weakness if that begins) so
the first step is a vet appointment.  After all if there is a blockage
which becomes complete then the vet has to jump fast to be successful.
If there is an infection the vet will want to treat.  If, if, if...
 
If there is not a readily obvious cause two things your vet will do
include doing a CBC with Chemistry Panel, and imaging the chest and
abdomen.
 
Kristina, sodium works as an important electrolyte for cellular function.
Salt is one way to provide this essential mineral.  If you have ever seen
a ferret in a Cushings Crisis (which is fatal) you have seen what sodium
levels that are too low can cause.  Just because humans often overdo salt
intake doesn't mean that salt does not serve a function in more
reasonable levels.
 
Jen, turmeric is an exciting foodstuff -- but NOT for any ferrets who
have insulinoma or ulcers.  It's most active compound is currently in
testing for use with human diabetes after preliminary work in an Indian
research facility indicated that it LOWERS blood glucose levels -- fine
for diabetes but the opposite of what you want with insulinoma.  It also
has related anti-inflammatory and anticoagulant properties under study.
(It also recently has had some exciting preliminary results in an
Alzheimers study.)
 
I don't have the time to look up the rest and the turmeric stuff is from
my head, but remember several discussed in either the FML or FHL, or
both, so check the Archives!
 
Also, ALWAYS CLEAR ANYTHING GIVEN TO A FERRET WITH THE TREATING VET FIRST
before using.  Sorry about shouting, but it is important.
 
Anything strong enough to heal is also strong enough to harm, so always
know the contraindications, medical conflicts, etc.
 
BTW, there is a new edition of the _PDR for Herbal Meds_ coming out.  I
gave details in the FHL already so check the archives there.
[Posted in FML issue 4887]