Prednisone is broken down to prednisolone in the liver. The
prednisolone is what has the effect on the tumors. As long as the
ferret has a healthy liver, either one will work just fine, and
prednisone is less expensive.
If the liver is marginal, the extra load of converting the prednisone
can be problematic, and I've heard of cases where in ferrets with poor
liver function, the conversion didn't happen, or wasn't efficient, so
the prednisone didn't have the desired impact.
Kevin Farlee
[Posted in FML 7472]