If the ferret's liver is at all compromised the Prednisolone will be more effective than the Prednisone, so your vet may adjust the dose downward depending blood glucose results if this is being used for insulinoma. On the other hand, if it is being used for lymphoma or an autoimmune disorder the vet will only adjust the dose in relation to the concentration change. Bravo to you for noticing the concentration! It is an absolutely essential aspect to notice with medications but too many people do not do so. The higher the concentration, the more med there is in the same volume. For those here who have not paid attention to that: failure to do so can have the ferret getting the wrong dose so with liquid meds always check the mg/ml numbers on the bottle. The liver has to convert Prednisone to Prednisolone for the body to utilize it. The result is that a compromised liver can not convert much. For ferrets with very compromised livers Prednisone may as well be water but Prednisolone will still work. We had one who was markedly like that who needed the med for an autoimmune problem with the change to Prednisolone being such a win for him and totally turning his health around, and we have had a few over the decades who were somewhat like that. Sukie (not a vet) Ferrets make the world a game. Recommended ferret health links: http://pets.groups.yahoo.com/group/ferrethealth/ http://ferrethealth.org/archive/ http://www.miamiferret.org/ http://www.ferrethealth.msu.edu/ all ferret topics: http://listserv.ferretmailinglist.org/archives/ferret-search.html "All hail the procrastinators for they shall rule the world tomorrow." (2010, Steve Crandall) A nation is as free as the least within it. [Posted in FML 7812]