I have used Bio-spot on my ferret without any problems. She tries to wipe it off at first (just like after a bath) but then no problems. The sheets that you wipe them with to kill the adult fleas work wonders. This is the only thing I have ever used on her and I don't put it on every six months on whatever the directions say, only when I see fleas. When I see them, I wash her bedding and cage out really good and then wipe her down and put the bios pot on her shoulders. Hope this helps! Crystal Helton Document Examiner II Arkansas DF&A, State Procurement [Posted in FML issue 3748]