In the last news letter, Annonymous Poster, asked about ferrets going in
circles.  We had a ferret do this, I took him in to the vet.  Zeb had a
bladder infection, and a painful inner ear infection.  Zeb has had a
depressed immune system for a while, first cancer, then surgery, then age.
Anyhow, it was the ear infection that had him spinning in circles.
 
I have also seen ferrets with hypoglycemia do this, but they are also
drooling, staggering little zombies by the time they are this bad off.
Nutrical on the way to the vets is what we do when they are this bad off the
first time around, since they can go into convulsions from the low blood
sugar.  The second time around, we draw blood for the gluecometer by
quicking a toenail, and give sub=Q fluids following the vet's instructions
for dosage.  Since you didn't mention any other symptoms, I would guess that
the ear infection is more likely.
 
Good luck, Annonymous.  Hope this is helpful information.
 
Colleen of Wyrdhaven and the gang of Nine
[Posted in FML issue 1759]