Pred is a short term drug and typically it is given twice a day, sometimes three times a day. For some ferrets Prednisone doesn't work but Prednisolone does. That happens when a ferret's liver isn't up to the processing step which the former needs but the latter doesn't. For some, also, Diazoxide is a useful drug. It is NOT unusual for dosing to have to be adjusted (and adjustments are needed throughout the illness). The usual technique is to try a low dose first and up it if is doesn't hold. Call your vet. What other tests were done? CBC WITH Chemistry Panel? Imaging? I advise http://fhl.sonic-weasel.org , and also some of the vets' pages listed in the critical refs in http://www.ferretcongress.org especially http://www.afip.org/ferrets/index.html The stress itself of illness and of surgery has been known to start ulcers. There recently was an edition of "Ferrets" magazine with an excellent article by Dr. Bruce Williams on this topic. Ask your vet is trying Carafate would make sense for your ferret. Pretty much any pharmacy can fill a prescription for the liquid version which ferrets often accept very readily. It is unusual to have inappetence continuing this long after surgery of the growth was a milder one. What were the pathology results from the biopsies? Has an adrenal problem been considered? Here are some past mammary tumor (apocrine, hyperplasia secondary to adrenal tumor, etc.) vet comments: http://fhl.sonic-weasel.org/browse.php?msg=SG4105 http://fhl.sonic-weasel.org/browse.php?msg=SG468 http://fhl.sonic-weasel.org/browse.php?msg=SG448 http://fhl.sonic-weasel.org/browse.php?msg=YG9111 http://fhl.sonic-weasel.org/browse.php?msg=YG4682 http://fhl.sonic-weasel.org/browse.php?msg=SG7005 http://fhl.sonic-weasel.org/browse.php?msg=SG6389 [Posted in FML issue 4488]