The Ethics of Xenotransplantation

by Pascal Ferzli

The controversial concept of cross-species transplantation, also known as xenotransplantation, has existed in myths and science fiction stories for a long time. Today, the lack of human organ donors has prompted an intense research effort throughout the medical community in the potential for animal organ transplants. Building on the overwhelming success of human-to-human transplantation, xenotransplantation aims to reduce the demand-supply gap for organs. In this essay, I explore whether or not an individual who might benefit from xenotransplantation should be denied from these benefits due to the ethical implications that accompany this practice on a mass scale. In order to structure my essay, I have partitioned the ethical considerations of xenotransplantation into four main parts which I consider the most important in this debate: the individual receiving the xenograft, the Society which must incur the benefits and damages of decisions regarding xenotransplantation, the long-term effect on Humanity, and the concern for animals used for humans' benefits.

I am building this argument based on the premise that xenotransplantation can help save lives of human beings who might have otherwise died without it. This may seem misleading given the current bleak prognosis of xenotransplantation; however, my intent is to examine the ethical dimension of this without delving into the jargon that accompanies any complex surgical procedures such as xenotransplantation.

Nevertheless, there can be little opposition to the idea that any surgical operation brings with it risks that might jeopardize a patient's life. It is easy to imagine a case in which a patient might be willing to undergo xenotransplantation without wanting to assess the opportunity cost involved in this procedure: when a patient feels that the "newest technology" is the only chance he or she has, I feel that the doctor has a duty to refuse such operation on the basis of what I have termed "voluntary incompetence." Even if the patient has given the doctor an informed consent for such a transplant, the latter does not become ethical simply as a result of the apparent "kamikaze plunge" of the patient. Of course, advocates of xenotransplantation view the medical risks involved in xenotransplantation, namely the rejection of the donor's organ, infection resulting from the xenograft, and disease transmission, as dangers that accompany any routine surgical operation (Hoke, 1995, p.1): if the only party who stands to lose from the operation is the patient him or herself, then the patient's autonomous choice to "sign on the dotted line" has to be the predominant factor. Still, I can foresee instances in which the desire to recover from a deadly organ malfunction might overshadow the patient's full appraisal of the situation...The most optimistic outlook on this event is the fact that the patient will end up with an animal's organ in his body: even applying this scenario to ourselves in our imagination for a few seconds makes some of us shudder with fear. Individuals view their internal bodies as an extension of their identities, and soon after the xenotransplantation, some patients will realize the consequences of their actions on their self-concepts. Having an animal's organ in one's body has the potential to decrease our self-image despite intense counseling on the neutrality of this occurrence: I feel that this possibility which was referred to as the " 'yuk' factor" (Nature Biotechnology, editorial, 1996, p403), is a strong ethical opposition to the domain of xenotransplantation on the level of the individual involved.

Xenotransplantation has deeper implications that extend beyond the individual realm into a social dimension that makes ethical acceptability even more difficult to examine. We have arrived at a point in medicine in which a great majority of our antibiotics are becoming less and less effective in combating diseases because of the natural selection of mutant resistant strains of pathogens such as bacteria (Kondrashov, 1998,BIOES278 notes) . In fact, one of the liveliest oppositions to xenotransplantation is the relaxation of the barrier between human and animal diseases which will worsen our chances of containing the gigantic problem described above. The scientific community is still recovering from the recent elucidation of the "mad cow disease" which turned out to have mutated into a form capable of infecting human beings through consumption.

There is no positive flip side to this danger of xenotransplantation according to the experts in the field; recently, a world renowned primate virologist named Jonathan Allan from the Southwest Foundation for Biomedical Research in San Antonio addressed the possibility of viruses being able to jump the species gap and transfer to human beings. He declared that "primates are known to carry undiscovered viruses. In 1994, eight or nine baboons at Southwest were infected with a mysterious nervous-system virus which was later identified as a new virus" (Hoke, 1995,p.1).

Adopting a precautionary approach could turn out to be ethical in the worst-case scenario: the consequentialist examination of society's recourse in the event that a new virus is discovered probes the issue of our morality if we isolate the infected human recipients and treat them as specimens until the mode of transmission of the diseases is understood.

In my opinion, this example is necessary to give us an in-depth understanding of what the ethicality of xenotransplantation involves. However, dismissing the ethical acceptability of xenotransplantation on mere possibilities would be unethical because of its detrimental effect on the science of medicine in its search for the alleviation of suffering of patients. I think that if we view the substantiation of this event from a more proportionally balanced approach, we will come to a more optimistic view. A minority of researchers in xenotransplantation do echo this point. In fact, shortly after Allan's declarations, John Atkinson of the School of Medicine at Washington University in St. Louis who is researching the effects of pig xenotransplants concluded that "a new virus is a theoretical possibility, but I can't imagine that with all our contact with pigs over thousands of years, that it would be a major problem." (Hoke, 1995, p.1)

The widespread objection to xenotransplantation is issued from utilitarian ethical theory which was embraced by the Nuttfield Council on Bioethics. They reemphasized that it is not ethical for an individual to affect negatively the whole human population as a result of a singular decision: "the risks associated with the possible transmission of infectious diseases as a consequence of xenotransplantation have not been adequately dealt with. It would be unethical, therefore, to use [xenografts] involving human beings." (Nuttfield Council on Bioethics,1996, p.27)

While new epidemics remain, for the present time, only caveats to animal organ use, a very real consideration is the macroallocation of resources in health care which will affect the society considering human-to-animal transplantation. The latter is just a small part of the medical realm, and yet it is certainly a very expensive field due to the complex manipulations necessary for a successful xenotransplantation. The ethical dilemma arises because our global economic system is built on limited resources juxtaposed to unlimited wants. The idea of depriving an individual suffering from organ malfunction of care because of society's interests in treating other diseases is not unique to xenotransplantation(Wikler, 1992, p.398); having said that, the appropriateness and ethicality of society's decision is extremely relevant to whether or not an individual who might survive from a xenograft is going to have this option in the hospital. If we do decide to spend money on this field, then one should be quick to examine the benefits lost through the investment into other domains (e.g. cancer treatment) in order to make it an ethical decision. Even if we attempt to disregard the economic burden of xenotransplantation as well as the potential for radiation of new diseases, the human society will have to come to terms with what it means to be human in the long-term. Some have argued that our mental capabilities including foresight, feelings,...etc set us apart from other living beings. In that case, encouraging xenografting may be a moral decision since that will serve to reinforce our convictions, by forcing us to look beyond the physical into individuals' "inner beauty" (Speyer-Ofenberger, personal communication,1998).

Many will object to this characterization of Humanity because they view appearance as an integral part of being human. Opponents of the perseverance in this domain often use the expression "playing God" to refer to the unethical use of animals to save human beings. Their most meaningful objection is based on the "unnaturalness" of such practices. These arguments are well-intended but I disagree with their extremist implications. It is indeed very difficult to define what is natural and to be able to distinguish from what is unnatural without running into some difficulties. A recent article in the Journal of Medical Ethics states that "on one account everything that humans do is by definition unnatural, because it constitutes an interference with the non-human natural order... On another account nothing that humans do is unnatural, since humans are themselves a part of nature." (Hughes, 1998,p.19) Another relevant point which deters from the "naturalness" argument is the fact that any alterations made to the patient are somatic, meaning that they will not be passed on to any offspring, and temporary since the transplanted organ can at any time be removed or replaced with a human organ. I feel that looking at xenotransplantation as a temporary transition phase that will help many patients survive until a better solution is uncovered is a rational method of evaluating the ethical dimensions of cross-species transplantation without becoming overwhelmed with horrifying images originating from science fiction.

On the other hand, our reckless use of animals may cause mayhem in the "natural order" in its effect on the animals, and this should lead us to question the morality of doing so. A hastened assessment will direct us to a false conclusion that may be phrased in the following way: since it is ethical to use animals for consumption, then their use as organ donors should be even more acceptable. Indeed, using animals for organs may well be looked upon as a more efficient use of animals, which will lead to an increase in their social value and worth.

Also, justifying the use of nonhumans for organs as being ethical simply because of our membership into the human species is misguided and superficial. In order to make animal use for saving a human being's life ethical, one has to justify this use based on the superiority of humans over animals in a certain aspect (Hugues, 1998,p.22). Superior brain and mental capacities are obvious candidates, but that excludes mentally retarded individuals from the batch: I feel that most people would agree with me that the use of mentally retarded individuals for organs would certainly be unethical. In any case, the ethics balance of proponents for the use of animals would still outnumber the opponents if it weren't for the long-term irreversible evolutionary changes described next.

First, in order to prevent disease acquisition in the donor animals, increased suffering on the part of the animal of choice (e.g. pigs) in the form of isolated development and rigorous viral and bacterial tests is inevitable. More importantly, these specialized farms will probably make use of the complex genetic knowledge that we have acquired in the last decade to modify these animals so that the compatibility of their organs to those of humans will become greater. The increased resemblance of the animals' organs to those of humans will make it more and more unethical to use them simply for organs. Even more problematic is the increased compatibility of the genetic make-up of humans and genetically altered animals which will transform the boundary between humans and nonhumans into a chaotic blur.

Arguments also arise regarding the difference between different animals. I can identify two parties that differ in their approaches to the ethical use of animals for xenotransplantation. The uniformists view nonhuman animals as equal with regards to their use for organ transplants; they regard the use of any animals, including nonhuman primates as ethical because of their use to save precious human lives.

The evolutionists, on the other hand, will view the use of chimpanzees as ethically unacceptable as opposed to pigs, and they base their views on the degree of genetic similarities between the animals and the human. The advantage of this view is that it establishes a framework whereby closely related species are respected, but drawing the line is problematic because there are so many factors that can used as segregating factors. In addition, one may be decreasing the potential for the use of the most compatible organ if such limitations are put in place. In retrospect, the ethical considerations of the use of animal organs for xenotransplantation in order to save a human life could only be approached through a holistic examination of all the different actors in such a practice. Limiting the investigation temporally and spatially to include only living human beings would have been misleading and incomplete. Throughout this paper, I have attempted to expose all possible sides by expanding on the strong points made by both proponents and opponents of xenotransplantation. I have included my opinion on some aspects of this debate which concern me most in coming up with the "least worst" strategy (Rhoden, p 46, 1986), but I tried my best to allow the reader to come up with his or her own conclusions based on the hierarchical resolution outline that I have proposed. I would like to end this exposition by raising my concern for what I regard as a "gold rush" to xenotransplantation. Regardless of the ethical considerations of this practice, many scientists will still decided to pursue this field in order to achieve fame. It is unfortunate but true that as long as there is a difference in the morality of different people, the refusal to explore xenotransplantation will not be a long-term stable strategy: there will always be some that will be willing to open Pandora's box.


Allan, Jonathan S. 1994. Letter to the Editor. Science 265:1345.

Hoke, Franklin.As Cross-species Transplantations Move Ahead, Some Scientists Call for Caution, Restraint. The Scientist, vol 9, #16, August 21, 1995.

Hugues, Jonathan. Xenografting:ethical issues. Journal of Medical Ethics 1998; 24: 18-24.

Kondrashov, Alexey S. BIOES278 course notes, Cornell University, 1998.

Nuttfield Council on Bioethics. "Animal-to-Human transplants: the ethics of Xenotransplantation". London: Nuttfield Council on Bioethics, 1996:27.

Rhoden, Nancy K., "Treating Baby Doe: the ethics of uncertainty," Hastings Center Report, Vol 16, No. 4, 1986, pp.34-43.

Wikler, Daniel. "Ethics and rationing: whether, how, or how much?" Journal of the American Geriatrics Society, Vol.40, 1992, p 398-403

Pascal Ferzli is enrolled in a Masters Program in Physiology and Biophysics at Georgetown University.