Yes, I've used metronidazole (a/k/a flagyl) before on many occasions.
The good news is that it usually works very well.  The bad news is that
ferrets absolutely hate it and act like you're trying to kill them when
you give it to them.
 
It's perfectly safe to draw up a little linatone or ferretone into the
syringe ahead of the metronidazole.  It won't fool your little weasel,
though.  You can also give a little linatone/ferretone afterwoard to get
rid if the nasty taste.  That usually makes ferrets forget the nasty
stuff you just gave them.
 
Hang in there.
 
All the best,
Caity and the fantastic five
[Posted in FML issue 4864]