在醫學研究中的動物使用

在醫學研究中的動物使用

 

簡介

 

  貫穿整個歷史，動物（這里指非人類動物，不包括人）被廣泛地應用于不同領域。然而，在醫學研究中使用動物的問題特別地引起了公眾的關注，因為對很多人來講，這似乎是違背自然的并且粗魯的，盡管用于其他用途的動物和受暴露的不良后果（如獵殺）的動物數量可能往往更大，因為估計每年全球用于實驗的50000000動物只占動物總量的0.2%（梅珀姆，2008）。

 

對動物實驗的爭議大體上涉及兩個不同的問題。首先，做動物實驗真的能獲得從其他來源得不到的有用知識嗎。第二，以某種方式破壞性地使用動物在道德上真的能被接受嗎？（取自生命倫理學之紐菲爾德理事會，2005）。科學論證的問題，顯然是道德論證問題的根本。

 

科學層面的判定

 

“如果沒有大量的動物用于實驗，現在就不會有口服小兒麻痹癥疫苗。如果沒有動物研究，小兒麻痹癥仍會每年剝奪數以千計的生命”（取自薩斌，1995）

  在研究中使用動物的主要原因是19世紀大多數醫療進步都來源于動物研究（梅珀姆，2008）。其中的例子有第一激素的提取（1902），梅毒的化學處理（1909），胰島素的分離（1920），現代麻醉學的產生（20），腎移植（40），化療治療白血病（1960），和腦膜炎疫苗（1980）（梅珀姆，monamy，2009；2008）。薩斌在1995年認為，那些動物實驗無用論者忽視了一個事實，那就是動物實驗已經對發展解救那些數不勝數的人類生命的醫藥起了作用，比如1957年小兒麻痹癥疫苗的發展。

 

Using animals in medical research

 

簡介——Introduction

 

     Throughout history, animals (refers to ‘non-human animals', excluding human) are widely used in different fields. However, the issue of using animals in medical research notably attract public attention because, to many people, it appears unnatural and cruel, even though the number of animals used for other purposes and the ill-effects exposed (eg. blood sport) may often be greater, because the estimated 50 million animals used annually in experiments worldwide only account for about 0.2% of all animals used (Mepham, 2008).

 

     The debate about animal experimentation ranges broadly over two distinct questions. Firstly, do animal research yields useful knowledge that could not be gained from other source and secondly, is it morally acceptable to use animals in a way that cause them harm (Nuffield Councils on Bioethics, 2005). The question of scientific justification is, obviously, fundamental to the question of moral justification.#p#分頁標題#e#

 

科學層面的判定——Scientific Justification

 

Justified

 

‘There could have been no oral polio vaccine without the use of innumerable animals. Without animal research, polio would still be claiming thousands of lives each year.' (Sabin, 1995)

 

The primary reason given for using animals in research is that most medical advances since the 19th century have resulted from research using animals (Mepham, 2008). Among the examples are the extraction of first hormone (1902), a chemical treatment for syphilis (1909), isolation of insulin (1920), modern anaesthetics (1920s), kidney transplants (1940s), chemotherapy for leukaemia (1960s), and meningitis vaccine (1980s) (Monamy, 2009; Mepham, 2008). According to Sabin (1995), those who view animal experimentation as useless overlook the fact that it has been instrumental in developing medicines that saved countless human lives, such as the development of polio vaccine in 1957.

 

Next, halting animal research would have unfavourable consequences for human health and welfare since there are no viable alternatives to animal experimentation yet (Mepham, 2008). Paris (1994), too, expressed that ‘all of the work being put into improving health care system will be for nought if we allow a powerful band of self-righteous activists to deny us the privilege of studying non-human animals - medical science's most valuable tool in the fight against disease.'

 

Lastly, animal experimentation is justified due to the extensive biological similarities between the physiology of humans and non-human animals (Mepham, 2008). This is supported by Bernard (1865), who stated that ‘the vital units, being of like nature in all living beings, are subjected to the same organic laws...' Even if the knowledge itself cannot be directly applied to humans, they add to the level of understanding that may eventually be exploited in human medicine (LaFollette & Shanks, 1996).

 

In short, animal experimentation is essential to ensure scientific progresses. We live in a modern age where life-threatening diseases are kept at bay to an extraordinary degree, bringing about the majority of us to forget that as recently as 60 years ago, many diseases (eg. TB, polio) were common killers in our society (Monamy, 2009).

 

Unjustified

 

However, there are also people who believe that animal experimentation is scientifically unjustified. For example, Burgos (1996) brought forward the argument that ‘it is impossible to cure a sick human by experimenting on animals, just like how it is not possible to cure a sick cat by experimenting on humans. Every species have different biomechanical and biochemical entity, and it is difficult to extrapolate data from one species to another. Moreover, every species reacts differently to different substances. For instances, aspirin kills cats and penicillin kills guinea pigs. Yet, the same guinea pig can safely eat strychnine- one of the deadliest poisons for human, but not for monkeys. Sheep can swallow enormous amount quantities of arsenic. Potassium cyanide, deadly for humans, is harmless for owl.'#p#分頁標題#e#

 

Supposing that one has chosen the best model for a human disease, it is still difficult to decide the dosage of the drug for humans. The thalidomide tragedy is one of the many examples of how things can go wrong. The sedative drug thalidomide was introduced in 1956 and widely used by pregnant women to reduce nausea and vomiting. But by 1960s, it was identified as the cause of phocomelia- a devastating birth defect in which the limbs do not form properly and long bones in the arms or legs are absence (Mepham, 2008).

 

Another example that shows the limitations of animal studies in assessing human reactions to drugs was dramatically illustrated by the detrimental effects experienced by the six male volunteers to the oral administration of TGN1412, a drug developed to treat rheumatism (Mepham, 2008). Although the drug had been tested on animals without deleterious effect, it produced life-threatening reaction on humans.

 

道德層面的判定——Ethical Justification

 

Cartesian

 

Today, few will argue that animals are like machines and have no souls, hence granting us the rights to use animals in any ways that we see suited. However, back at the 17th century, this human-centred view was very prevalent. Rene Descartes (1596-1650), especially, played an important role in the early debate. Descartes (1637) believed that ‘the divine gift of soul distinguished the human from all others' and the reactions of animals were dismissed as mere reflex. This, as a result, provided a convenient ideology for early vivisectionists (Monamy, 2009).

Descartes' statement was, also, supported by British psychologist Nicholas Humphrey. ‘...Descartes was as nearly right as makes no matter. If we walk down on English country lane, we walk by ourselves. Trees, birds, bees, the rabbit darting down its hole, the cow heavy with milk are all as without insight into their condition as the dummies on show at Madame Tussaud's.' (Humphrey, 1983)

 

Such views are not widely held anymore, partly due to the fact that studies of self-recognition using chimpanzees and mirrors have shown that some animals are capable of recognising themselves and have self-consciousness (Monamy, 2009).

 

Kantian

 

     Immanuel Kant echoed the voice of ancients: non-human animals are non-rational, and hence demonstrably inferior to humans. However, he added a philosophical twist that helps ground one very common argument used to morally justify our treatment of animals (LaFollette & Shanks, 1996).He believed that as far as animals are concerned, we have no direct duties. Animals have no self-conscious and are there as means to an end. Our duties towards animals are merely indirect duties towards humanity (Kant, 1963; Monamy, 2009). ‘Animal nature has analogies to human nature, and by doing our duties to animals in respect of manifestation of human nature, we are directly do our duty towards humanity.' However, he argued that overt cruelty to animals was to be avoided because how we threat animals does affect how we threat humans. ‘...he who is cruel to animals becomes hard also in his dealings with men.'#p#分頁標題#e#

 

     Within Kant we, therefore, identify two elements of current moral thought about animals: the belief that humans are superior to animals because of our intelligence, and that we have some duties towards animals. These uphold the belief that although we should not be cruel to animals, we can use them for our purposes (LaFollette & Shanks, 1996).

 

     The problem with Kantian theory is its failure to make a theoretical distinction between animal species beyond human sphere. This theory can morally justify the use of a chimpanzee in an experiment where a mouse would suffice, because neither species has moral autonomy (Monamy, 2009).

 

動物福利/利害關系——Animal Welfare/Interest

 

‘The day may come when the rest of the animal creation may acquire those rights which never could have been withholden from them but by the hand of tyranny...... The question is not, can they reason? Nor can they talk? But, can they suffer?' (Jeremy Bentham, 1789)

 

The first person to bring up the idea of equality was Bentham. He pointed out that the capacity to suffer should be a vital characteristic that gives a being the right to equal consideration. This was further upheld by Peter Singer's Animal Liberation. Singer, reviving Bentham's utilitarianism, argued for the liberation of animals based on equality of consideration and their capacity to suffer (Monamy, 2009). ‘The capacity for suffering and enjoying things is a prerequisite for having interest at all. Hence, it would be nonsense to say that it was not in the interest of a stone to be kicked along the road. A stone does not have interest because it cannot suffer. Nothing that we can do to it could possibly make any difference to its welfare. A mouse, on the other hand, does have an interest in not being harm, because it will suffer if it is.'

 

Moral judgements must be made based on equal interest and, we should never be influenced by species, in the same way as we should never be influenced by race or sex (Monamy, 2009). ‘If an animal suffered, there can be no moral justification for refusing to take suffering into consideration. No matter what the nature of the being, the principle of equality requires that its suffering be counted equally with the like suffering- in so far as rough comparisons can be made- of any being.' (Singer, 1974)

 

Singer argued that since laboratory animals were capable of feeling pain, their interest must be considered morally by humans. If the level of suffering in an experiment is not outweighed by any increase in the quality of human life, it is morally indefensible to allow such an experiment to continue (Dolan, 1999; Monamy, 2009).

The idea put forward by Singer have provided a sensible starting point for debate over the moral issues essential in any discussion of animal experimentation. Virtually everyone, now, acknowledges that many animals, certainly mammals, feel pain- even though there is still disagreement about the severity or nature of the pain. Plus, majority too agrees that we cannot do whatever we want to the animals, at least if it causes the animals pain (LaFollette & Shanks, 1996; Monamy, 2009).#p#分頁標題#e#

 

However, there are still some weaknesses concerning Singer's argument. Firstly, moral calculations become impractical when all factors are taken into consideration. How do you quantify an amount of pain and pleasure? Or the benefits of an experiment to mankind? Secondly, Regan (1986) argued that utilitarianism has ‘no room for the equal rights of different individuals because it has no room for their equal inherent value or worth. What has value is the satisfaction of an individual's interest, not the individual itself.' Regan believed that this theory can easily be exploited since an evil means can be justified as long as there is a good end. Lastly, some suggested that it simply do not go far enough- there is more to life than pleasure and pain (Monamy, 2009). Charles Birch (1993) posed an interesting question: ‘If all animals used for human purposes were to be constantly anaesthetised for all their lives, thereby eliminating the pain/pleasure argument, would such a procedure be morally defensible?'

 

動物權利——Animal Rights

 

     Animal rights moral view was brought forwarded by Tom Regan (1986). According to him, basic moral rights should be assigned to all beings who are ‘subjects of life', due to the fact that ‘these animals have a life of their own, of importance to them apart from their utility to us. They have a biography, not just a biology. They are not only in the world, they have experience of it. They are somebody, not something.'

 

Regan claimed that all creatures should be treated equally unless there is some relevant reason that justifies otherwise. It thereby rules out discrimination based on irrelevant reasons. He proposed that every individual of any species should be considered to have an ‘intrinsic value' (or ‘inherent value'), the value of conscious individuals, disregarding of their usefulness to others and independent of their ‘goodness'. Equal rights for such individuals protect their ‘inherent value' and give them moral status (Mepham, 2008; Monamy, 2009).

 

When it comes to animal experimentation, Regan's view is unequivocal: ‘...the rights-based view is categorically abolitionist...this is just as true when animals are used in trivial, duplicative, unnecessary or unwise research as it is when they are used in studies that hold out real promise of human benefits...the best we can do is - not to use them.'

 

     Nonetheless, some claims that ‘rights' can be attributed only to individuals who can claim them, and that they can only apply in circumstances where that individual understands the notions of ‘rights'. However, Regan has countered this by pointing out that such a viewpoint would also withhold rights form infants, the mentally retarded and senile. Apart from that, many find the concept of animal rights confusing. Exactly what rights do animals have? Do every single animal, including insects, has the same right, or just mammals? (Mepham, 2008; Monamy, 2009; Dolan, 1999)#p#分頁標題#e#

 

對生命的崇敬——Reverence for Life

 

     Albert Schweitzer (1875-1965) believed that an ethic that advocated goodness towards all life and, not just to humanity, would be derived from emotion, not from rational thought. This belief contributed to his theory of ‘reverence for life'.

 

‘The most immediate fact of man's consciousness is the assertion: I am life which wills to live in the midst of life which wills to life...he feels a compulsion to give every will-to-live the same reverence for life that he gives to his own....He accepts as being good: to preserve life, to promote life, to raise to its highest value of life which is capable of development.'(Schweitzer, 1936)

 

It is an ideology which makes no distinction between ‘higher' and ‘lower' life forms, plants and animals, human and non-human. Acceptance of the ethic does not mean that it is wrong to cause death of another creature, it is the causing of pain or death when it can be avoided that is wrong. Anyone guided by this belief will only cause death or suffering of any animal in cases of inescapable necessity, never from thoughtlessness (Monamy, 2009).

 

     ‘Those who experiment with operations or the use of drug upon animals....must never quiet misgivings they feel with the general reflection that their cruel proceedings aim at a valuable result. They must first have considered in each individual case whether there is a real necessity to force upon any animal this is sacrifice for the sake of mankind. And they must take the most anxious care to mitigate as much as possible the pain inflicted.' (Schweitzer, 1936)

 

     In short, Schweitzer urged that all life must be given the same respect: the need for every experiment must be carefully reasoned based on the ideal of reverence for life, not sentience - an argument that gives a place to emotion (Monamy, 2009).

 

結論——Conclusion

 

     ‘...there are no simple answers to be found and there is no single guiding principle that will answer the questions that are raised about the problems of animal welfare and the use of animals in our society....where ethical principles are concerned, there is no possibility of proving the validity of an ethical principle...' (Stone, 1989)

 

In conclusion, the debate on animal experimentation is extremely complicated and it involves both rational discussion and personal feelings. Every one of us must, therefore, attempt to form an opinion of our own about the extent to which we use research animals.