TRANSPLANTING A PIG’S HEART VALVE INTO A HUMAN BODY

QUESTION:

Surgeons have recently considered the possibility of using pigs’ hearts for transplanting into human bodies which need a new heart. They say that a pig’s heart so closely resembles a human heart that such a transplant is feasible. What would be the attitude of the Jewish legal tradition to such an operation? (Question asked by Rabbi Beryl Cohon of Boston.)

ANSWER:

IF, AS THE physicians say, a pig’s heart is feasible for transplant into a human body, then from the medical and legal point of view such transplants would be superior to the present practice of transplanting human heart valves into human bodies. The present practice has given rise to new and worrisome legal problems. Was not the donor body really killed by the removal of its viable heart? Also, if the donor body had been the victim of a murderous attack, the defense lawyers can well claim it was not their client but the doctors who actually killed the victim. Clearly, there is now great need of a new medical and legal definition of what constitutes death. All such questions would disappear immediately if, instead of human hearts, animal hearts would be used for transplants. If, therefore, they are physiologically suitable, the use of them will certainly be socially preferable. But, of course, the question that is raised here is whether such animal transplants, specifically a pig’s heart, would be acceptable to the spirit and perhaps even the letter of Jewish law.

At the outset, it must be observed and acknowledged that the very idea of a human being with a pig’s heart awakens a shudder and almost a sense of disgust in the mind of the person who hears of it for the first time. This sense of disgust is not to be brushed aside as mere prejudice, for it has a certain weight in Jewish law. Certain foods, certain gifts to the altar are forbidden, not because they are really and objectively forbidden, but because they awaken disgust. They are forbidden, as the phrase is, because of ugliness, or disgust (mishum mius). Thus the Shulchan Aruch (Yoreh Deah 116:6) as do other codes, forbids for food certain things which are actually permitted but “which a man’s soul shudders at.” The forbidding of ugly and dirty things, mishum mius, is based upon the Scriptural verse in Leviticus 11:43. “Do not make your souls disgusting. This sense of disgust must indeed be reckoned with. Yet, basically, since we are dealing here with patients whose lives are in grave danger (since only such need the transplants) then the prohibition which is based upon disgust must be set aside. Although rooted in a Scriptural text, it is after all only a Rabbinical or secondary prohibition and must give way before the important general principle that “we may heal with anything except the three cardinal sins of idolatry, bloodshed, and immortality” (b. Pesachim 25a). Maimonides makes this general rule clearer when he says (Hilchot Yesode Torah, 5:6) :

He who is sick and in danger of death and the physician tells him that he can be cured by a certain object or material which is forbidden by the Torah, he must obey the physician in order to be cured.

See also, Shulchan Aruch, Yoreh Deah, 155:3.

With regard to the transplant of a human heart into a human patient, there are certain special prohibitions which may counterbalance the general permissibility “to use any object for healing.” There is, first of all, the requirement that a human body must be buried completely and no part of it, even “as much as an olive” may be left unburied. This, by the way, is one of the chief Orthodox objections to autopsy, namely, that parts of the body dissected will be left unburied. But, clearly, this prohibition of complete burial has no relevance as a religious law with regard to animals. There is no requirement for the complete burial of animals.

There is, however, another hindrance with regard to the use of part of a human body. There is a general principle stated in all the codes (based on Sanhedrin 47b) that the body of the dead may not be used for the benefit of the living (met asur behanaah). But this rule which protected the dignity of the body of the dead against abuse cannot be applied to animals because, after all, we do consume the body of animals. If, therefore, the physicians would be proposing the implantation of the heart of a calf or a cow, which of course may be consumed by Jews, into the body of a living person, then the prohibition of “benefiting from the body of the dead” would have no application. Besides, the rule mentioned certainly means that the dead body of a human being may not be used for the benefit of living human beings.

But this new proposal involves the body of a trefah animal which by Jewish law may not be consumed as food. Is it, then, permitted to have any benefit from the body of trefah animals? In general, the law is that Jews may not have any benefit, business benefit specifically, from the sale of pork (see Yoreh Deah 117:1). But that applies only to the parts that are eaten. Certainly there is no prohibition in dealing with pig’s bristles for brushes. But even as food, there is some leniency in dealing with pork, at least with buying it, not by way of a man’s regular business, but to give to one’s Gentile workmen. Of course this prohibition against “bene-fiting” from the trefah animal does not apply to Gen-tile patients who are not forbidden (even in Jewish law) to eat pork or to benefit from it. But even this doubt as to a Jew being permitted to benefit from the flesh of a pig (and which really is confined to regular business with such meat) would be set aside in the question of saving life.

There is still another consideration involved in this problem which would not apply in the case of a human heart transplanted into a human body. Is not the transplanting of part of an animal body into a human body a violation of the law against mixing of breeds (kil’e behemah) ? It is surely forbidden, based upon the Bible (Leviticus 19:19) to mix breeds of animals (see Mishnah Bava Kama V:7; see also, Shulchan Aruch, Yoreh Deah 297). Is not this implantation of an animal’s heart into a human body similar to the method used in the hybridization of plants? A slip from one variety of plants is grafted on to the stock of another variety. By means of this implantation a new species is obtained. Would not, therefore, this proposed operation be forbidden on the ground of hybridization?

But this suggested analogy with the method of hy-bridizing plants is not a correct one. Animals are not hybridized by grafting but by sexual mating. I do not know whether in actual practice it would be at all possible to change one animal specie into another by grafting or implantation of the glands or heart of one type of animal into another. Be that as it may, in all discussions of animal hybridization in the Jewish legal literature, only the method of mating is known. With regard to the mating of different species, there is considerable discussion. A study of the law indicates (Yoreh Deah 297) that what is actually forbidden is the actual act of mating the different species and really assisting in the mating. But if the animals are just put together in one corral and they mated without other human assistance, no sin has been committed by the farmer. In fact, the offspring of such mixed breed is permitted for use. There is no prohibition of hanaah of the mixed animal. And if the two unrelated animals are both kasher, the meat of the mixed animal is permitted for food. So clearly the prohibition based upon the mixture in this transplant not being a sexual mating but a mere physical juxtaposition, it constitutes no objection in the case of necessary healing.

Of course this permission depends upon reliable doctors giving a fair assurance first, that the operation is indispensable and second, that it has a reasonable likelihood of success. In that case, all the doubts, the sense of revulsion, the benefit (hanaah) from a trefah animal, the mixing of breeds, must be set aside because of the general principle: “Nothing must stand in the way of saving a life”; (En lecha davar sheomed bifne pikuach nefesh [ Yoma 82a]).