Randy Cohen takes up this question, in "The Ethicist" this week:
I am an anesthesiologist. Patients undergoing cardiac surgery routinely receive the intravenous blood thinner heparin, derived from pigs. Alternatives exist but are not F.D.A.-approved for this use and are probably less safe. Recently we had a devoutly Jewish patient. Should we have asked him whether a pig-derived product was acceptable or simply used what we knew to be most appropriate medically? Likewise, should we ask vegetarians about animal-based medical products? NAME WITHHELD, SACRAMENTO
His answer starts:
When in doubt, ask. The doctrine of informed consent is meant to put patients in control of their own care. It is the role of the doctor to provide the patient with the information needed to exercise that control. While you needn’t discuss heparin’s manufacture with all patients — most simply won’t care — you would do well to alert devout Jews or Muslims or vegetarians, who might have concerns about such things. more hereBut it seems to me: the information is out there. Why is it the doctor's responsibility to provide it?