The staring profile you give could be several things but is a fine fit
for early insulinoma -- a very common non-malignant condition that many
ferrets get.  The stumbling profile can be more advanced insulinoma and
47 is not good -- well below borderline.
 
Here are the general next steps: have vet do a blood glucose test and if
not too low to risk fasting (47 can be too low -- esp. with such marked
symptoms) then do a fasting glucose tolerance test.  In Monday's FML is a
list of resources I provided: put "SEND FERRET 3683" in the body of a
message -- and nothing else in there -- and send it to
<[log in to unmask]> to get Monday's FML if you didn't save it.
Several of those resources will help greatly.
 
>The doc says if its turns out not to be insulinoma, the second most likely
>option is a brain lesion.  Oh, wonderful!  :-(
 
Not necessarily the end of the world; Steve and i have had ferrets who
have had thromboses that healed up almost perfectly despite being so
extreme that the ferrets were almost dead for a few days afterward.  If
it may be that sort of problem then you go looking next step for things
that can cause thrown clots: esp.  cardiomyopathy (which is treatable not
for cure but for added quality and quantity of life) and kidney disease.
Dilative cardiomyopathy (but not its refinements that influence treatment
and need and ultrasound) shows up on x-ray often but hypertrophic usually
needs an ultrasound to be diagnosed.
 
I am not a vet -- just someone who has had ferrets in the family for 20
years this coming June, who has run a past list for and of
ferret-specialist vets (except for me), and is now a co-moderator of the
Ferret Health List, etc.  (So, I know a bit -- but nowhere near enough.
DO read those websites in which vets tell about such things esp.  since
they are VERY EASY to find using the list of resources I sent to the FML!
Also, know that it can sometimes take a while to find an effective
medication dose for a given individual (and that may change over time)
which is why so many useful resources like Karen Purcell's vet text,
_Essentials of Ferrets, a Guide for Practitioners_, 1-800-252-2242, print
medication RANGES.)
[Posted in FML issue 3684]