While we have never had a vet operate due to numbers alone for insulinoma, once there are symptoms present they DO operate rapidly and we've been VERY happy with the results. The only times that the ops have not been rapid ones over the many years have been when Fritter had it and people didn't know what to do way back then plus she also had lympho, and for two ferrets which had to delay for health reasons --one to be built up some first and another due to other serious illnesses also present (though in her case the surgery finally had to be risked and worked fine). The points others are making about time involved, borderline numbers, etc. are excellent ones and smack dab on the mark. Remember that early symptoms can be as mild as "distracted" periods with inactivity, or more sleepiness than earlier. Don't forget to read up on the problem in: 1. http://www.ferretcentral.org 2. http://www.afip.org/ferrets/index.html 3. http://www.miamiferret.org/fhc [Posted in FML issue 2977]