Q: Does it hurt ferrets to eat raisins?
A: Raisins are not a natural food for ferrets, and we need to be very careful when we feed a food like raisins to ferrets. Raisins are chock full of sugar; and we know that feeding simple sugars is not good for ferrets. Raisins are dried fruit, not a normal food item for ferrets.
Do one or two raisins once a day harm a ferret? We are not sure. One or two a day may seem unlikely to cause any harm, but with so much worry about the potential causes of insulinoma in ferrets, the big picture may look very different than the day-to-day reality. Is it possible that a lifetime of raisins given once a day predisposes ferrets to insulinoma disease? That question still remains unanswered.
My choice would be to give ferrets a more ferret-friendly type of treat — one that is meat-based and not full of simple sugars.