When searching for how long a medication lasts, type in the medication name followed by half-life - i.e. "prednisone half-life" ... prednisone is converted to prednisolone (conversion rate, half-life of 1 hour), and the half-life of of prednisolone is 2-3 hours ... however, the "duration of action" is stated as 18 - 36 hours. What does this mean in terms of your ferret? I always ask my vet, and therefore recommend that. [Posted in FML 6472]