James and Bits, There are several medications to treat ear mites. In my experience tresaderm is not very effective to treat ear mites. In any case it is best to clean the ers out prior to each application because the mites are under the wax, and if the medication does not contact the mites they will not die. Some vet say a ferret has ear mites when technically it is bacteria or yeast causing the problem (in these cases the tresaderm can be effective). The vet can tell the difference by looking at the wax under the microscope. Good Luck, Dr Weiss [log in to unmask] 301-299-4142 [Posted in FML issue 1287]