Biological Ethics
Table of contents
Chapter 27. Animal experimentation
N. López Moratalla and G. Herranz
a) The use of animals in experiments
The employment of animals in experimentation has been, and still is, an aspect core topic in the advancement of some medical and biological sciences. knowledge Their use has brought considerable benefits, especially in the biomedical sciences, as such research has led to an ever deeper understanding of the characteristics of the living organism and its physiology, and, on this basis, it has been possible to design, study and test new drugs that have had a positive impact on human health. The development of new medicines and food preparations makes it necessary to experiment on animals, as well as on programs of study aimed at the "welfare" or health of the animals themselves, or on programs of study aimed at studying in depth the biological characteristics of endangered species in order to find out what affects them, etc.
From a technical point of view, it is necessary to take proper care of the health and physical conditions of the animals on laboratory. Malnutrition, stress, hygienic conditions or disease due to deficiencies in their status, may diminish or modify the animal's responses and, therefore, the appropriate experimental results would not be achieved, since they could be different from those that would correspond to a normal state. It is necessary, also in most research, to have a uniform population that allows the animals used in an experiment to be as homogeneous as possible in terms of their characteristics.
Since ancient times, biological testing laboratories have bred some of the experimental animals they needed to use for their work. Breeding was almost always limited to rats, mice and guinea pigs. The rest of the animals, such as dogs and cats, were generally obtained from the municipal collection of abandoned animals. Others came from animal breeders and livestock farms. However, it has become increasingly clear that there is a need to have a larger number of animals available at issue , subjected to a process of maintenance and breeding, under conditions of stricter control, in suitable stables, which offer more guarantees; and, at the same time, animal breeding centres - stables - have emerged, run by staff qualified staff and with the necessary facilities.
Experimental animals must be cared for, in terms of food, hygiene, comfort conditions - such as temperature, space, etc. - not only because of the possible complications that may arise in the interpretation of the results of the experiments, or to prevent them from suffering from infections or diseases that render them useless, or because if they are not treated properly they become irascible and tend to bite, scratch, etc, but also for the animal itself, because it would be unethical and unprofessional to make the animal suffer unnecessarily, or for the sake of suffering.
Any limitation in animal experimentation has its basis in man, insofar as man's behaviour towards animals cannot be destructive. When harm is done to an animal, it must be strictly necessary for the purpose of experimentation, and if not, it must be limited as much as possible. To do harm simply for the sake of doing harm is ethically unlawful because of the moral disorder that cruelty and despotic domination entail in man.
b) Legislation for the use of animals in experiments
In many countries, legislation has been established to place certain limitations on and regulate the use of animals in scientific experimentation, and committees have been set up to monitor compliance and to denounce any perceived abuse or cruelty1 2.
As early as 1875, the British Parliament published the so-called "Cruelty Animal Act" regulating the performance of experiments that could cause pain to vertebrate animals. Such experiments could only be carried out in institutions which had previously obtained the permission of the Home Secretary and by researchers who had obtained the required licences and certificates. In order to completely avoid causing pain, the regulation not only requires that anaesthetics must always be used, but also regulates the use of anaesthetics on subject and stipulates that the animal must be killed at the end of the experiment while still under anaesthesia. It also requires that the experiments must be completely necessary for human health, so that they cannot be used, for example, to acquire internship guide or to illustrate lectures.
Some of the restrictions can be lifted, if the appropriate licence is obtained. Such licences are reference letter, mainly for so-called pain conditions, and state that, if during the development experiment the animal is observed to be in pain, it must be killed, without causing additional pain. This is certainly not achieved if the animal is agitated during the operation or remains conscious after use. Actual euthanasia depends on how quickly the anaesthetic effect on the animal is achieved and maintained until death occurs. If the method employee is carried out by a nervous or unconscious person internship, euthanasia will not be achieved. It is therefore recommended that sufficient internship knowledge of the selected method of killing dead animals is obtained beforehand and under the supervision of an experienced person. There are many methods of painless killing of animals. The employment of one or the other depends on the species or the purpose for which the animal is used.
This law, which seems to some to be quite strict, has since its inception in 1876 come in for a great deal of criticism, as in the opinion of many it is clearly insufficient. Although 83 additional recommendations were introduced in 1965, there are still groups of opponents of animal experimentation, with such infamous actions as those of the Animal Liberation Front -group , a radical British group with 200 members - who raid laboratories, zoos, restaurants - for serving frogs' legs - or poison chocolate bars, causing the deaths of children, because signature ruined the teeth of monkeys with its experiments.
It is obviously part of the ethics of researcher to ensure that experiments using animals are as humane as possible. In fact, all researcher, perhaps unconsciously and guided by its own knowledge of pain, tends to treat animals - especially those closest to it on the evolutionary scale - with care. In this sense, legislation provides guidelines that help and, at the same time, allow for the penalisation of incorrect behaviour, without the need, on the other hand, to go to extremes that indicate not so much ethical sensitivity but a clear inversion of values between man and animal in which it is precisely man who is the worst off. The existence of such extensive and detailed legislation on the use of animals in experimentation is striking, in contrast to the legislation on the use of human foetuses in experimentation, or abortion practices.
Legislation in various countries contains provisions on the use of experimental animals, on the specific form of the internship of the experiment and also on the responsibilities of the scientists. For animal experimentation to be legally permissible, it is considered to be necessary if it is really necessary to achieve a greater good such as health. This is the case if the aims are prophylactic, diagnostic or therapeutic. If experiments cannot immediately bring about health benefits, they can only be carried out to the extent that they lead to a significant advance in knowledge about the constitution and functioning of living beings. They are only admissible - both on research and teaching- in cases where there are really no alternative ways. And they must always comply with the rules of rigour inherent to the scientific spirit: that they are aimed at obtaining original results, that the hypothesis is supported by data obtained, the guarantee that the methods chosen are correct, etc.
With regard to the experimental internship , legislation is primarily aimed at ensuring that the minimum of pain is inflicted on the animal. This generally requires that the animals on laboratory are properly treated, adequately fed and kept under appropriate hygienic conditions. Experiments requiring the use of live animals should be carried out or directly supervised by a veterinarian or other qualified scientist. In addition, all experiments that may cause harm or suffering to the animals must be performed under anaesthesia, in order to avoid unnecessary pain to the animal; the animal may only be killed awake in those cases where it is certified that anaesthesia interferes with or invalidates the experimental purpose , in which case the experiment must be properly C and supervised by the team leader of research. If survival of the animal is not required after completion of an acute experimental process, the animal should be killed by procedures that ensure minimal suffering and immediate effect, and the animal should be verified to be dead before disposal. If the nature of the experiment requires the survival of the animal, the animal's condition and subsequent outcome should be monitored. Postoperative care should minimise the discomfort and suffering of the animal during the convalescence period, from agreement with standard veterinary practice.
c) Alternatives to employment of experimental animals
It is also worth reflecting on the extent to which the employment of animals in experiments is justified. Every year, more than 75 million mice, rats, rabbits and guinea pigs are killed for "science", along with cats, dogs, monkeys, zebras and other more exotic animals. Can it be said that all of them are necessary? In some types of experimentation it does not seem that they can be replaced. Some cardiovascular research requires the employment of a model as close as possible to that of a human, and there is no doubt that the employment of a sheep, monkey or other animal is fundamentally justified. However, this is not always the case.
There is no denying that research on animals has provided invaluable medical information. But it can be argued that some biomedical research causes animals to suffer or to be killed unnecessarily. Millions of animals die each year in what might be called crude toxicity tests, and in very many cases the employment of animals could be dispensed with if more attention were paid to development of techniques from laboratory that can be used as alternatives, as long as they provide data with the same conclusions and at least the same Degree confidence. This idea of employment of alternative techniques has gained a lot of interest, but it has different meanings for different groups. In its most extreme conception, it would mean replacing the animal in experimentation altogether. issue But it can also mean a reduction in the number of animals required, or a reduction of their suffering through refinement of the techniques to be used3.
Replacement of the animal
Of the three possibilities, total replacement of the animal is the most difficult to achieve, but not totally impossible, as the following examples illustrate.
Friedmann developed a pregnancy test in the 1930s, test , which consisted of injecting a rabbit with urine from a woman, and after a few days the rabbit was opened. If the animal had ovulated, the test was positive, i.e. the woman was pregnant. Eventually it became known that gonadotrophin was manager responsible for the stimulation of ovulation and a simple chemical test for this hormone, which is carried out in a tube of essay , was developed and has been in use for the last ten to fifteen years. A simple tube from essay has replaced a rabbit.
issue Another test that has avoided the use of a large number of animals is the one developed by Bruce Ames in the 1970s to detect potentially mutagenic and carcinogenic substances. The test makes use of Salmonellae and, as millions of them can be used to test a particular substance, it allows the detection of very low mutation frequencies, thus not only substituting animals, but also improving the sensitivity of the test.
Reduction of issue of animals to be used
We have already mentioned how it is not always possible to dispense with animals in experimentation, but it is possible, in some cases, to reduce the issue employee at each essay. One method is based on the use of tissue cultures, which are potentially more effective and less costly than animals. Today, the pharmaceutical and chemical industries are paying increasing attention to employment tissue cultures for intermediate tests, even if the latter must be carried out on an animal.
The following example gives an idea of what can be achieved in terms of animal employment and efficiency by adopting tests that can be performed in Petri dishes. A laboratory investigating antiviral compounds reduced the issue number of mice used over 15 months from 13000 to 2000 and increased the issue number of chemicals tested from 2000 to 24000, simply by introducing tissue cultures.
Reduction of pain caused by
If the issue of animals cannot be reduced, an alternative is to develop more refined methods that avoid as much as possible any subject suffering. issue For example, a large number of experiments require the more or less continuous injection of a certain substance, for which one or more catheters are placed in the animal. In order to prevent the animal from removing the catheters, it was kept in cages, so that it could not move during the study period, which could last for months. Today, systems have been designed to keep them in place and protected from any action by the animal that would jeopardise the stability of the catheter.
In 1981, A.N. Rowan published a paper article, in which he emphasises the millions of dollars and animals wasted by laboratories in performing toxicity tests, and highlights in particular tests that should be changed immediately. Both cause great suffering to the animal, with very limited gain in return4. One of them is the so-called "LD-50 test" (Lethal-Dose-50%), developed 50 years ago to estimate the potency of digitalis (a potent cardiotopic and diuretic derived from Digitalis). The test consists of administering increasing doses of the drug under study, until a dose (the LD-50) is obtained that causes the death of 50% of the animals. Undoubtedly, there are drugs whose potency cannot be estimated by any other means, e.g. anti-rabies serum. But the "LD-50 test" has become established as the standard test for assessing the potency of all substances, to the extent that it is applied to essentially non-toxic substances. The test has been severely criticised both by groups outside research and by toxicologists. Zbinden of the high school of Toxicology at the University of Zurich and toxicologist of the WHO - World Health Organisation - has described it as "a ritual execution of animals en masse"; Baker of the Imperial Chemical Industries in England expressed his opinion as follows: issue " data obtained from the "LD-50 test" is of little use and very costly because of the large number of animals involved. The most important information that can be obtained from such a test is the value of the dose required to commit suicide".
The WHO has announced an alternative to the LD-50 which is to use cell cultures. However, organisations such as The Environmental Protection Agency and The Food and Drug Administration require that every new substance Chemistry be subjected to the "LD-50 test", otherwise it will be classified as a poison.
It is not an easy and simple matter to eliminate animal testing. Lederer5 points out that it is sometimes essential, and quotation gives as an example the history of the use of saccharin. When its sweetening power was discovered in 1879 and the classic toxicology tests of the time were carried out, it began to be used in 1886 by diabetics, and from 1950 onwards to prevent weight gain, and was especially recommended for pregnant women. In 1970 it was suspected of having a teratogenic effect. Results with pregnant rats, tests with Salmonellae, and programs of study of its action on yeast chromosomes are contradictory. Experiments in several laboratories - some of which required the use of 2,500 rats - to study effects in successive generations showed a carcinogenic effect of saccharin, not in its passage to the foetus during gestation, but via the mammary gland, if ingested during the lactation period. Tests avoiding employment on the live animal are sometimes insufficient, either because the metabolism of the substance may involve more than one tissue, or because they affect absorption phenomena, natural defence, or have implications for reproduction.
Another test reference letter Rowan refers to is the Draize test, which has been used for 40 years to detect the irritant power of cosmetics and cleaning products. The method consists of applying drops of the product to be tested to the eyes of rabbits. The animals are often anaesthetised and their eyes are subjected to long periods of experimentation, sometimes lasting several weeks, to see whether the cornea is unaffected or whether it becomes inflamed or ulcerated. Although test gives some idea about the potential ability of the substance on essay to irritate human skin or eyes, the information is crude and unreliable: different researchers obtain varying results with the same substance. In short, test produces a high Degree of suffering and little refinement. The "Draize test" was widely attacked in 1980 by a coalition of societies that pointed out the high level of animal suffering that the cosmetics industry entailed. As a result, the major cosmetics companies Revlon, Avon, Estée Lauder and Chanel have donated millions of dollars to subsidize to find alternatives to the Draize test, in order not to see their sales decline. One alternative could be the use of corneal cell cultures in this subject test.
All these examples show that until the 1970s no one had seriously concerned themselves with finding alternatives to the employment use of animals in experimentation. Fortunately, this concern for animal welfare in research has experienced a considerable boom in recent years, and has become one of the aspects to be considered for the ethics of scientific research .
Notes
(1) "NIH Suspends Funding of Resarcher Charged with Animal Cruelty". Bioscience, 31, 714, 1981.
(2) BRITT, D. "Ethics, ethical committees and animal experimentation". Nature, 311, 503, 1984.
(3) BALLS, M. "Replacing experiments on laboratory animals". TIBS, 11, 236-238, 1986.
(4) ROWAN, A.N. "The test tube alternative". Science, 214, 16-34, 1981.
(5) LEDERER, J. "Ethics of the research animal". Arch. B. Med. Soc. Hyg., 42, 169, 1984.