why animal testing is unnecessary essay

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Arguments against animal testing

Animal experiments are cruel, unreliable, and even dangerous

The harmful use of animals in experiments is not only cruel but also often ineffective. Animals do not naturally get many of the diseases that humans do, such as major types of heart disease, many types of cancer, HIV, Parkinson’s disease or schizophrenia. Instead, signs of these diseases are artificially induced in animals in laboratories in an attempt to mimic the human disease. Yet, such experiments belittle the complexity of human conditions which are affected by wide-ranging variables such as genetics, socio-economic factors, deeply-rooted psychological issues and different personal experiences.

It is not surprising to find that treatments showing “promise” in animals rarely work in humans.  Not only are time, money and animals’ lives being wasted (with a huge amount of suffering), but effective treatments are being mistakenly discarded and harmful treatments are getting through. The support for animal testing is based largely on anecdote and is not backed up, we believe, by the scientific evidence that is out there.

Despite many decades of studying cancer, Alzheimer’s disease, Parkinson’s disease, diabetes, stroke and AIDS in animals, none of these conditions have reliable and fully effective cures and some don’t even have effective treatments.

The history of cancer research has been the history of curing cancer in the mouse. We have cured mice of cancer for decades and it simply didn’t work in human beings.

Unreliable animal testing

• 92% of drugs fail in human clinical trials despite appearing safe and effective in animal tests, often on safety grounds or because they do not work.
• Urology drugs have the lowest success rate (only 4% are approved after entering clinical trials) followed by heart drugs (5% success rate), cancer drugs (5% success rate) and neurology drugs (6% success rate).
• Our research has shown that using dogs, rats, mice and rabbits to test whether or not a drug will be safe for humans provides statistically little useful insight. Our study also revealed that drug tests on monkeys are just as poor as those using any other species in predicting the effects on humans.
• A recent study found that out of 93 dangerous drug side effects, only 19% could have been predicted by animal tests.
• Another study showed that over 1,000 potential stroke treatments have been “successful” in animal tests, but of the approximately 10% that progressed to human trials, none worked sufficiently well in humans.
• One review of 101 high impact discoveries based on basic animal experiments found that only 5% resulted in approved treatments within 20 years. More recently, we conducted an analysis of 27 key animal-based ‘breakthroughs ’ that had been reported by the UK press 25 years earlier. Mirroring the earlier study, we found only one of the 27 “breakthroughs” had been realised in humans, and that was subject to several caveats.

Dangerous animal testing

• Vioxx, a drug used to treat arthritis, was found to be safe when tested in monkeys (and five other animal species) but has been estimated to have caused around 140,000 heart attacks and strokes and 60,000 deaths worldwide.
• Human volunteers testing a new monoclonal antibody treatment (TGN1412) at Northwick Park Hospital, UK, in 2006 suffered a severe immune reaction and nearly died. Testing on monkeys at 500 times the dose given to the volunteers totally failed to predict the dangerous side effects.
• A drug trial in France resulted in the death of one volunteer and left four others severely brain damaged in 2016. The drug, which was intended to treat a wide range of conditions including anxiety and Parkinson’s disease, was tested in four different species of animals (mice, rats, dogs and monkeys) before being given to humans.
• A clinical trial of Hepatitis B drug fialuridine had to be stopped because it caused severe liver damage in seven patients, five of whom died. It had been tested on animals first.

Animals are different

• Animals do not get many of the diseases we do, such as Parkinson’s disease, major types of heart disease, many types of cancer, Alzheimer’s disease, HIV or schizophrenia.
• An analysis of over 100 mouse cell types found that only 50% of the DNA responsible for regulating genes in mice could be matched with human DNA.
• The most commonly used species of monkey to test drug safety (Cynomolgous macaque monkeys) is resistant to doses of paracetamol (acetaminophen) that would be deadly in humans.
• Chocolate, grapes, raisins, avocados and macadamia nuts are harmless in humans but toxic to dogs.
• Aspirin is toxic to many animals and would not be on our pharmacy shelves if it had been tested according to current animal testing standards.

The science relating to animal experiments can be extremely complicated and views often differ. What appears on this website represents Cruelty Free International expert opinion, based on a thorough assessment of the evidence.

FIND OUT MORE ABOUT ANIMAL TESTING

Alternatives to animal tests are often cheaper, quicker and more effective.

Alternatives to animal testing

subtitle: Alternatives to animal tests are often cheaper, quicker and more effective.

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Established in 1898, Cruelty Free International is firmly rooted in the early social justice movement and has a long and inspiring history.

Our History

subtitle: Established in 1898, Cruelty Free International is firmly rooted in the early social justice movement and has a long and inspiring history.

Animal testing is carried out in a wide range of areas, including biological research, and testing medicines and chemicals.

Types of animal testing

subtitle: Animal testing is carried out in a wide range of areas, including biological research, and testing medicines and chemicals.

Millions of animals are used and killed in the name of progress every year.

Facts and figures on animal testing

subtitle: Millions of animals are used and killed in the name of progress every year.

Animals used in laboratories are deliberately harmed, not for their own good, and are usually killed at the end of the experiment.

What is animal testing?

subtitle: Animals used in laboratories are deliberately harmed, not for their own good, and are usually killed at the end of the experiment.

Science Publications

Should Animals Be Used for Scientific or Commercial Testing?

• History of Animal Testing

Animals are used to develop medical treatments, determine the toxicity of medications, check the safety of products destined for human use, and other  biomedical , commercial, and health care uses. Research on living animals has been practiced since at least 500 BC.

Descriptions of the dissection of live animals have been found in ancient Greek writings from as early as circa 500 BC. Physician-scientists such as  Aristotle ,  Herophilus , and  Erasistratus  performed the experiments to discover the functions of living organisms.  Vivisection  (dissection of a living organism) was practiced on human criminals in ancient Rome and Alexandria, but prohibitions against mutilation of the human body in ancient Greece led to a reliance on animal subjects. Aristotle believed that animals lacked intelligence, and so the notions of justice and injustice did not apply to them.  Theophrastus , a successor to Aristotle, disagreed, objecting to the vivisection of animals on the grounds that, like humans, they can feel pain, and causing pain to animals was an affront to the gods. Read more background…

Pro & Con Arguments

Pro 1 Animal testing contributes to life-saving cures and treatments for humans and animals alike. Nearly every medical breakthrough in the last 100 years has resulted directly from research using animals, according to the California Biomedical Research Association. To name just a few examples, animal research has contributed to major advances in treating conditions including breast cancer, brain injury, childhood leukemia, cystic fibrosis, multiple sclerosis, and tuberculosis. Testing on animals was also instrumental in the development of pacemakers, cardiac valve substitutes, and anesthetics. [ 9 ] [ 10 ] [ 11 ] [ 12 ] [ 13 ] Scientists racing to develop a vaccine for coronavirus during the 2020 global pandemic needed to test on genetically modified mice to ensure that the vaccine did not make the virus worse. Nikolai Petrovsky, professor in the College of Medicine and Public Health at Flinders University in Australia, said testing a coronavirus vaccine on animals is “absolutely essential” and skipping that step would be “fraught with difficulty and danger.” [ 119 ] [ 133 ] Researchers have to test extensively to prevent “vaccine enhancement,” a situation in which a vaccine actually makes the disease worse in some people. “The way you reduce that risk is first you show it does not occur in laboratory animals,” explains Peter Hotez, Dean for the National School of Tropical Medicine at Baylor College. [ 119 ] [ 141 ] Further, animals themselves benefit from the results of animal testing. Vaccines tested on animals have saved millions of animals that would otherwise have died from rabies, distemper, feline leukemia, infectious hepatitis virus, tetanus, anthrax, and canine parvo virus. Treatments for animals developed using animal testing also include pacemakers for heart disease and remedies for glaucoma and hip dysplasia. [ 9 ] [ 21 ] Animal testing has also been instrumental in saving endangered species from extinction, including the black-footed ferret, the California condor and the tamarins of Brazil. The American Veterinary Medical Association (AVMA) endorses animal testing to develop safe drugs, vaccines, and medical devices. [ 9 ] [ 13 ] [ 23 ] Read More

Pro 2 Animals are appropriate research subjects because they are similar to human beings in many ways. Chimpanzees share 99% of their DNA with humans, and mice are 98% genetically similar to humans. All mammals, including humans, are descended from common ancestors, and all have the same set of organs (heart, kidneys, lungs, etc.) that function in essentially the same way with the help of a bloodstream and central nervous system. Because animals and humans are so biologically similar, they are susceptible to many of the same conditions and illnesses, including heart disease, cancer, and diabetes. [ 9 ] [ 17 ] [ 18 ] Animals often make better research subjects than humans because of their shorter life cycles. Laboratory mice, for example, live for only two to three years, so researchers can study the effects of treatments or genetic manipulation over a whole lifespan, or across several generations, which would be infeasible using human subjects. Mice and rats are particularly well-suited to long-term cancer research, partly because of their short lifespans. [ 9 ] [ 29 ] [ 30 ] Further, animals must be used in cases when ethical considerations prevent the use of human subjects. When testing medicines for potential toxicity, the lives of human volunteers should not be put in danger unnecessarily. It would be unethical to perform invasive experimental procedures on human beings before the methods have been tested on animals, and some experiments involve genetic manipulation that would be unacceptable to impose on human subjects before animal testing. The World Medical Association Declaration of Helsinki states that human trials should be preceded by tests on animals. [ 19 ] [ 20 ] A poll of 3,748 scientists by the Pew Research Center found that 89% favored the use of animals in scientific research. The American Cancer Society, American Physiological Society, National Association for Biomedical Research, American Heart Association, and the Society of Toxicology all advocate the use of animals in scientific research. [ 36 ] [ 37 ] [ 38 ] [ 39 ] [ 40 ] [ 120 ] Read More

Pro 3 Animal research is highly regulated, with laws in place to protect animals from mistreatment. In addition to local and state laws and guidelines, animal research has been regulated by the federal Animal Welfare Act (AWA) since 1966. As well as stipulating minimum housing standards for research animals (enclosure size, temperature, access to clean food and water, and others), the AWA also requires regular inspections by veterinarians. [ 3 ] All proposals to use animals for research must be approved by an Institutional Animal Care and Use Committee (IACUC) set up by each research facility. Most major research institutions’ programs are voluntarily reviewed for humane practices by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC). [ 24 ] [ 25 ] Animal researchers treat animals humanely, both for the animals’ sake and to ensure reliable test results. Research animals are cared for by veterinarians, husbandry specialists, and animal health technicians to ensure their well-being and more accurate findings. Rachel Rubino, attending veterinarian and director of the animal facility at Cold Springs Harbor Laboratory, says, “Most people who work with research animals love those animals…. We want to give them the best lives possible, treat them humanely.” At Cedars-Sinai Medical Center’s animal research facility, dogs are given exercise breaks twice daily to socialize with their caretakers and other dogs, and a “toy rotation program” provides opportunities for play. [ 28 ] [ 32 ] Read More

Con 1 Animal testing is cruel and inhumane. Animals used in experiments are commonly subjected to force feeding, food and water deprivation, the infliction of burns and other wounds to study the healing process, the infliction of pain to study its effects and remedies, and “killing by carbon dioxide asphyxiation, neck-breaking, decapitation, or other means,” according to Humane Society International. The US Department of Agriculture reported in Jan. 2020 that research facilities used over 300,000 animals in activities involving pain in just one year. [ 47 ] [ 102 ] Plus, most experiments involving animals are flawed, wasting the lives of the animal subjects. A peer-reviewed study found serious flaws in the majority of publicly funded US and UK animal studies using rodents and primates: “only 59% of the studies stated the hypothesis or objective of the study and the number and characteristics of the animals used.” A 2017 study found further flaws in animal studies, including “incorrect data interpretation, unforeseen technical issues, incorrectly constituted (or absent) control groups, selective data reporting, inadequate or varying software systems, and blatant fraud.” [ 64 ] [ 128 ] Only 5% of animals used in experiments are protected by US law. The Animal Welfare Act (AWA) does not apply to rats, mice, fish, and birds, which account for 95% of the animals used in research. The types of animals covered by the AWA account for fewer than one million animals used in research facilities each year, which leaves around 25 million other animals without protection from mistreatment. The US Department of Agriculture, which inspects facilities for AWA compliance, compiles annual statistics on animal testing but they only include data on the small percentage of animals subject to the Act. [ 1 ] [ 2 ] [ 26 ] [ 28 ] [ 135 ] Even the animals protected by the AWA are mistreated. Violations of the Animal Welfare Act at the federally funded New Iberia Research Center (NIRC) in Louisiana included maltreatment of primates who were suffering such severe psychological stress that they engaged in self-mutilation, infant primates awake and alert during painful experiments, and chimpanzees being intimidated and shot with a dart gun. [ 68 ] Read More

Con 2 Animal tests do not reliably predict results in human beings. 94% of drugs that pass animal tests fail in human clinical trials. Over 100 stroke drugs and over 85 HIV vaccines failed in humans after succeeding in animal trials. Nearly 150 clinical trials (human tests) of treatments to reduce inflammation in critically ill patients have been undertaken, and all of them failed, despite being successful in animal tests. [ 57 ] [ 58 ] [ 59 ] Drugs that pass animal tests are not necessarily safe. The 1950s sleeping pill thalidomide, which caused 10,000 babies to be born with severe deformities, was tested on animals prior to its commercial release. Later tests on pregnant mice, rats, guinea pigs, cats, and hamsters did not result in birth defects unless the drug was administered at extremely high doses. Animal tests on the arthritis drug Vioxx showed that it had a protective effect on the hearts of mice, yet the drug went on to cause more than 27,000 heart attacks and sudden cardiac deaths before being pulled from the market. [ 5 ] [ 55 ] [ 56 ] [ 109 ] [ 110 ] Plus, animal tests may mislead researchers into ignoring potential cures and treatments. Some chemicals that are ineffective on (or harmful to) animals prove valuable when used by humans. Aspirin, for example, is dangerous for some animal species. Intravenous vitamin C has shown to be effective in treating sepsis in humans, but makes no difference to mice. Fk-506 (tacrolimus), used to lower the risk of organ transplant rejection, was “almost shelved” because of animal test results, according to neurologist Aysha Akhtar. A report on Slate.com stated that a “source of human suffering may be the dozens of promising drugs that get shelved when they cause problems in animals that may not be relevant for humans.” [ 105 ] [ 106 ] [ 127 ] Read More

Con 3 Alternative testing methods now exist that can replace the need for animals. Other research methods such as in vitro testing (tests done on human cells or tissue in a petri dish) offer opportunities to reduce or replace animal testing. Technological advancements in 3D printing allow the possibility for tissue bioprinting: a French company is working to bioprint a liver that can test the toxicity of a drug. Artificial human skin, such as the commercially available products EpiDerm and ThinCert, can be made from sheets of human skin cells grown in test tubes or plastic wells and may produce more useful results than testing chemicals on animal skin. [ 15 ] [ 16 ] [ 50 ] [ 51 ] Michael Bachelor, Senior Scientist and Product Manager at biotech company MatTek, stated, “We can now create a model from human skin cells — keratinocytes — and produce normal skin or even a model that mimics a skin disease like psoriasis. Or we can use human pigment-producing cells — melanocytes — to create a pigmented skin model that is similar to human skin from different ethnicities. You can’t do that on a mouse or a rabbit.” The Environmental Protection Agency is so confident in alternatives that the agency intends to reduce chemical testing on mammals 30% by 2025 and end it altogether by 2035. [ 61 ] [ 134 ] [ 140 ] Scientists are also able to test vaccines on humans volunteers. Unlike animals used for research, humans are able to give consent to be used in testing and are a viable option when the need arises. The COVID-19 (coronavirus) global pandemic demonstrated that researchers can skip animal testing and go straight to observing how vaccines work in humans. One company working on a COVID-19 vaccine, Moderna Therapeutics, worked on developing a vaccine using new technology: instead of being based on a weakened form of the virus, it was developed using a synthetic copy of the COVID-19 genetic code. [ 142 ] [ 143 ] Read More

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• J Prev Med Hyg
• v.63(2 Suppl 3); 2022 Jun

Ethical considerations regarding animal experimentation

Aysha karim kiani.

1 Allama Iqbal Open University, Islamabad, Pakistan

2 MAGI EUREGIO, Bolzano, Italy

DEREK PHEBY

3 Society and Health, Buckinghamshire New University, High Wycombe, UK

GARY HENEHAN

4 School of Food Science and Environmental Health, Technological University of Dublin, Dublin, Ireland

RICHARD BROWN

5 Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada

PAUL SIEVING

6 Department of Ophthalmology, Center for Ocular Regenerative Therapy, School of Medicine, University of California at Davis, Sacramento, CA, USA

PETER SYKORA

7 Department of Philosophy and Applied Philosophy, University of St. Cyril and Methodius, Trnava, Slovakia

ROBERT MARKS

8 Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel

BENEDETTO FALSINI

9 Institute of Ophthalmology, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy

NATALE CAPODICASA

10 MAGI BALKANS, Tirana, Albania

STANISLAV MIERTUS

11 Department of Biotechnology, University of SS. Cyril and Methodius, Trnava, Slovakia

12 International Centre for Applied Research and Sustainable Technology, Bratislava, Slovakia

LORENZO LORUSSO

13 UOC Neurology and Stroke Unit, ASST Lecco, Merate, Italy

DANIELE DONDOSSOLA

14 Center for Preclincal Research and General and Liver Transplant Surgery Unit, Fondazione IRCCS Ca‘ Granda Ospedale Maggiore Policlinico, Milan, Italy

15 Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy

GIANLUCA MARTINO TARTAGLIA

16 Department of Biomedical, Surgical and Dental Sciences, Università degli Studi di Milano, Milan, Italy

17 UOC Maxillo-Facial Surgery and Dentistry, Fondazione IRCCS Ca Granda, Ospedale Maggiore Policlinico, Milan, Italy

MAHMUT CERKEZ ERGOREN

18 Department of Medical Genetics, Faculty of Medicine, Near East University, Nicosia, Cyprus

MUNIS DUNDAR

19 Department of Medical Genetics, Erciyes University Medical Faculty, Kayseri, Turkey

SANDRO MICHELINI

20 Vascular Diagnostics and Rehabilitation Service, Marino Hospital, ASL Roma 6, Marino, Italy

DANIELE MALACARNE

21 MAGI’S LAB, Rovereto (TN), Italy

GABRIELE BONETTI

Astrit dautaj, kevin donato, maria chiara medori, tommaso beccari.

22 Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy

MICHELE SAMAJA

23 MAGI GROUP, San Felice del Benaco (BS), Italy

STEPHEN THADDEUS CONNELLY

24 San Francisco Veterans Affairs Health Care System, University of California, San Francisco, CA, USA

DONALD MARTIN

25 Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC-IMAG, SyNaBi, Grenoble, France

ASSUNTA MORRESI

26 Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy

ARIOLA BACU

27 Department of Biotechnology, University of Tirana, Tirana, Albania

KAREN L. HERBST

28 Total Lipedema Care, Beverly Hills California and Tucson Arizona, USA

MYKHAYLO KAPUSTIN

29 Federation of the Jewish Communities of Slovakia

LIBORIO STUPPIA

30 Department of Psychological, Health and Territorial Sciences, School of Medicine and Health Sciences, University "G. d'Annunzio", Chieti, Italy

LUDOVICA LUMER

31 Department of Anatomy and Developmental Biology, University College London, London, UK

GIAMPIETRO FARRONATO

Matteo bertelli.

32 MAGISNAT, Peachtree Corners (GA), USA

Animal experimentation is widely used around the world for the identification of the root causes of various diseases in humans and animals and for exploring treatment options. Among the several animal species, rats, mice and purpose-bred birds comprise almost 90% of the animals that are used for research purpose. However, growing awareness of the sentience of animals and their experience of pain and suffering has led to strong opposition to animal research among many scientists and the general public. In addition, the usefulness of extrapolating animal data to humans has been questioned. This has led to Ethical Committees’ adoption of the ‘four Rs’ principles (Reduction, Refinement, Replacement and Responsibility) as a guide when making decisions regarding animal experimentation. Some of the essential considerations for humane animal experimentation are presented in this review along with the requirement for investigator training. Due to the ethical issues surrounding the use of animals in experimentation, their use is declining in those research areas where alternative in vitro or in silico methods are available. However, so far it has not been possible to dispense with experimental animals completely and further research is needed to provide a road map to robust alternatives before their use can be fully discontinued.

How to cite this article: Kiani AK, Pheby D, Henehan G, Brown R, Sieving P, Sykora P, Marks R, Falsini B, Capodicasa N, Miertus S, Lorusso L, Dondossola D, Tartaglia GM, Ergoren MC, Dundar M, Michelini S, Malacarne D, Bonetti G, Dautaj A, Donato K, Medori MC, Beccari T, Samaja M, Connelly ST, Martin D, Morresi A, Bacu A, Herbst KL, Kapustin M, Stuppia L, Lumer L, Farronato G, Bertelli M. Ethical considerations regarding animal experimentation. J Prev Med Hyg 2022;63(suppl.3):E255-E266. https://doi.org/10.15167/2421-4248/jpmh2022.63.2S3.2768

Introduction

Animal model-based research has been performed for a very long time. Ever since the 5 th century B.C., reports of experiments involving animals have been documented, but an increase in the frequency of their utilization has been observed since the 19 th century [ 1 ]. Most institutions for medical research around the world use non-human animals as experimental subjects [ 2 ]. Such animals might be used for research experimentations to gain a better understanding of human diseases or for exploring potential treatment options [ 2 ]. Even those animals that are evolutionarily quite distant from humans, such as Drosophila melanogaster , Zebrafish ( Danio rerio ) and Caenorhabditis elegans , share physiological and genetic similarities with human beings [ 2 ]; therefore animal experimentation can be of great help for the advancement of medical science [ 2 ].

For animal experimentation, the major assumption is that the animal research will be of benefit to humans. There are many reasons that highlight the significance of animal use in biomedical research. One of the major reasons is that animals and humans share the same biological processes. In addition, vertebrates have many anatomical similarities (all vertebrates have lungs, a heart, kidneys, liver and other organs) [ 3 ]. Therefore, these similarities make certain animals more suitable for experiments and for providing basic training to young researchers and students in different fields of biological and biomedical sciences [ 3 ]. Certain animals are susceptible to various health problems that are similar to human diseases such as diabetes, cancer and heart disease [ 4 ]. Furthermore, there are genetically modified animals that are used to obtain pathological phenotypes [ 5 ]. A significant benefit of animal experimentation is that test species can be chosen that have a much shorter life cycle than humans. Therefore, animal models can be studied throughout their life span and for several successive generations, an essential element for the understanding of disease progression along with its interaction with the whole organism throughout its lifetime [ 6 ].

Animal models often play a critical role in helping researchers who are exploring the efficacy and safety of potential medical treatments and drugs. They help to identify any dangerous or undesired side effects, such as birth defects, infertility, toxicity, liver damage or any potential carcinogenic effects [ 7 ]. Currently, U.S. Federal law, for example, requires that non-human animal research is used to demonstrate the efficacy and safety of any new treatment options before proceeding to trials on humans [ 8 ]. Of course, it is not only humans benefit from this research and testing, since many of the drugs and treatments that are developed for humans are routinely used in veterinary clinics, which help animals live longer and healthier lives [ 4 ].

COVID-19 AND THE NEED FOR ANIMAL MODELS

When COVID-19 struck, there was a desperate need for research on the disease, its effects on the brain and body and on the development of new treatments for patients with the disease. Early in the disease it was noticed that those with the disease suffered a loss of smell and taste, as well as neurological and psychiatric symptoms, some of which lasted long after the patients had “survived” the disease [ 9-15 ]. As soon as the pandemic started, there was a search for appropriate animal models in which to study this unknown disease [ 16 , 17 ]. While genetically modified mice and rats are the basic animal models for neurological and immunological research [ 18 , 19 ] the need to understand COVID-19 led to a range of animal models; from fruit flies [ 20 ] and Zebrafish [ 21 ] to large mammals [ 22 , 23 ] and primates [ 24 , 25 ]. And it was just not one animal model that was needed, but many, because different aspects of the disease are best studied in different animal models [ 16 , 25 , 26 ]. There is also a need to study the transmission pathways of the zoonosis: where does it come from, what are the animal hosts and how is it transferred to humans [ 27 ]?

There has been a need for animal models for understanding the pathophysiology of COVID-19 [ 28 ], for studying the mechanisms of transmission of the disease [ 16 ], for studying its neurobiology [ 29 , 30 ] and for developing new vaccines [ 31 ]. The sudden onset of the COVID-19 pandemic has highlighted the fact that animal research is necessary, and that the curtailment of such research has serious consequences for the health of both humans and animals, both wild and domestic [ 32 ] As highlighted by Adhikary et al. [ 22 ] and Genzel et al. [ 33 ] the coronavirus has made clear the necessity for animal research and the danger in surviving future such pandemics if animal research is not fully supported. Genzel et al. [ 33 ], in particular, take issue with the proposal for a European ban on animal testing. Finally, there is a danger in bypassing animal research in developing new vaccines for diseases such as COVID-19 [ 34 ]. The purpose of this paper is to show that, while animal research is necessary for the health of both humans and animals, there is a need to carry out such experimentation in a controlled and humane manner. The use of alternatives to animal research such as cultured human cells and computer modeling may be a useful adjunct to animal studies but will require that such methods are more readily accessible to researchers and are not a replacement for animal experimentation.

Pros and cons of animal experimentation

Arguments against animal experimentation.

A fundamental question surrounding this debate is to ask whether it is appropriate to use animals for medical research. Is our acceptance that animals have a morally lower value or standard of life just a case of speciesism [ 35 ]? Nowadays, most people agree that animals have a moral status and that needlessly hurting or abusing pets or other animals is unacceptable. This represents something of a change from the historical point of view where animals did not have any moral status and the treatment of animals was mostly subservient to maintaining the health and dignity of humans [ 36 ].

Animal rights advocates strongly argue that the moral status of non-human animals is similar to that of humans, and that animals are entitled to equality of treatment. In this view, animals should be treated with the same level of respect as humans, and no one should have the right to force them into any service or to kill them or use them for their own goals. One aspect of this argument claims that moral status depends upon the capacity to suffer or enjoy life [ 37 ].

In terms of suffering and the capacity of enjoying life, many animals are not very different from human beings, as they can feel pain and experience pleasure [ 38 ]. Hence, they should be given the same moral status as humans and deserve equivalent treatment. Supporters of this argument point out that according animals a lower moral status than humans is a type of prejudice known as “speciesism” [ 38 ]. Among humans, it is widely accepted that being a part of a specific race or of a specific gender does not provide the right to ascribe a lower moral status to the outsiders. Many advocates of animal rights deploy the same argument, that being human does not give us sufficient grounds declare animals as being morally less significant [ 36 ].

ARGUMENTS IN FAVOR OF ANIMAL EXPERIMENTATION

Those who support animal experimentation have frequently made the argument that animals cannot be elevated to be seen as morally equal to humans [ 39 ]. Their main argument is that the use of the terms “moral status” or “morality” is debatable. They emphasize that we must not make the error of defining a quality or capacity associated with an animal by using the same adjectives used for humans [ 39 ]. Since, for the most part, animals do not possess humans’ cognitive capabilities and lack full autonomy (animals do not appear to rationally pursue specific goals in life), it is argued that therefore, they cannot be included in the moral community [ 39 ]. It follows from this line of argument that, if animals do not possess the same rights as human beings, their use in research experimentation can be considered appropriate [ 40 ]. The European and the American legislation support this kind of approach as much as their welfare is respected.

Another aspect of this argument is that the benefits to human beings of animal experimentation compensate for the harm caused to animals by these experiments.

In other words, animal harm is morally insignificant compared to the potential benefits to humans. Essentially, supporters of animal experimentation claim that human beings have a higher moral status than animals and that animals lack certain fundamental rights accorded to humans. The potential violations of animal rights during animal research are, in this way, justified by the greater benefits to mankind [ 40 , 41 ]. A way to evaluate when the experiments are morally justified was published in 1986 by Bateson, which developed the Bateson’s Cube [ 42 ]. The Cube has three axes: suffering, certainty of benefit and quality of research. If the research is high-quality, beneficial, and not inflicting suffering, it will be acceptable. At the contrary, painful, low-quality research with lower likelihood of success will not be acceptable [ 42 , 43 ].

Impact of experimentations on animals

Ability to feel pain and distress.

Like humans, animal have certain physical as well as psychological characteristics that make their use for experimentation controversial [ 44 ].

In the last few decades, many studies have increased knowledge of animal awareness and sentience: they indicate that animals have greater potential to experience damage than previously appreciated and that current rights and protections need to be reconsidered [ 45 ]. In recent times, scientists as well as ethicists have broadly acknowledged that animals can also experience distress and pain [ 46 ]. Potential sources of such harm arising from their use in research include disease, basic physiological needs deprivation and invasive procedures [ 46 ]. Moreover, social deprivation and lack of the ability to carry out their natural behaviors are other causes of animal harm [ 46 ]. Several studies have shown that, even in response to very gentle handling and management, animals can show marked alterations in their physiological and hormonal stress markers [ 47 ].

In spite of the fact that suffering and pain are personalized experiences, several multi-disciplinary studies have provided clear evidence of animals experiencing pain and distress. In particular, some animal species have the ability to express pain similarly to human due to common psychological, neuroanatomical and genetic characteristics [ 48 ]. Similarly, animals share a resemblance to humans in their developmental, genetic and environmental risk factors for psychopathology. For instance, in many species, it has been shown that fear operates within a less organized subcortical neural circuit than pain [ 49 , 50 ]. Various types of depression and anxiety disorders like posttraumatic stress disorder have also been reported in mammals [ 51 ].

PSYCHOLOGICAL CAPABILITIES OF ANIMALS

Some researchers have suggested that besides their ability to experience physical and psychological pain and distress, some animals also exhibit empathy, self-awareness and language-like capabilities. They also demonstrate tools-linked cognizance, pleasure-seeking and advanced problem-solving skills [ 52 ]. Moreover, mammals and birds exhibit playful behavior, an indicator of the capacity to experience pleasure. Other taxa such as reptiles, cephalopods and fishes have also been observed to display playful behavior, therefore the current legislation prescribes the use of environmental enrichers [ 53 ]. The presence of self-awareness ability, as assessed by mirror self-recognition, has been reported in magpies, chimpanzees and other apes, and certain cetaceans [ 54 ]. Recently, another study has revealed that crows have the ability to create and use tools that involve episodic-like memory formation and its retrieval. From these findings, it may be suggested that crows as well as related species show evidence of flexible learning strategies, causal reasoning, prospection and imagination that are similar to behavior observed in great apes [ 55 ]. In the context of resolving the ethical dilemmas about animal experimentation, these observations serve to highlight the challenges involved [ 56 , 57 ].

Ethics, principles and legislation in animal experimentation

Ethics in animal experimentation.

Legislation around animal research is based on the idea of the moral acceptability of the proposed experiments under specific conditions [ 58 ]. The significance of research ethics that ensures proper treatment of experimental animals [ 58 ]. To avoid undue suffering of animals, it is important to follow ethical considerations during animal studies [ 1 ]. It is important to provide best human care to these animals from the ethical and scientific point of view [ 1 ]. Poor animal care can lead to experimental outcomes [ 1 ]. Thus, if experimental animals mistreated, the scientific knowledge and conclusions obtained from experiments may be compromised and may be difficult to replicate, a hallmark of scientific research [ 1 ]. At present, most ethical guidelines work on the assumption that animal experimentation is justified because of the significant potential benefits to human beings. These guidelines are often permissive of animal experimentation regardless of the damage to the animal as long as human benefits are achieved [ 59 ].

PRINCIPLE OF THE 4 RS

Although animal experimentation has resulted in many discoveries and helped in the understanding numerous aspects of biological science, its use in various sectors is strictly controlled. In practice, the proposed set of animal experiments is usually considered by a multidisciplinary Ethics Committee before work can commence [ 60 ]. This committee will review the research protocol and make a judgment as to its sustainability. National and international laws govern the utilization of animal experimentation during research and these laws are mostly based on the universal doctrine presented by Russell and Burch (1959) known as principle of the 3 Rs. The 3Rs referred to are Reduction, Refinement and Replacement, and are applied to protocols surrounding the use of animals in research. Some researchers have proposed another “R”, of responsibility for the experimental animal as well as for the social and scientific status of the animal experiments [ 61 ]. Thus, animal ethics committees commonly review research projects with reference to the 4 Rs principles [ 62 ].

The first “R”, Reduction means that the experimental design is examined to ensure that researchers have reduced the number of experimental animals in a research project to the minimum required for reliable data [ 59 ]. Methods used for this purpose include improved experimental design, extensive literature search to avoid duplication of experiments [ 35 ], use of advanced imaging techniques, sharing resources and data, and appropriate statistical data analysis that reduce the number of animals needed for statistically significant results [ 2 , 63 ].

The second “R”, Refinement involves improvements in procedure that minimize the harmful effects of the proposed experiments on the animals involved, such as reducing pain, distress and suffering in a manner that leads to a general improvement in animal welfare. This might include for example improved living conditions for research animals, proper training of people handling animals, application of anesthesia and analgesia when required and the need for euthanasia of the animals at the end of the experiment to curtail their suffering [ 63 ].

The third “R”, Replacement refers to approaches that replace or avoid the use of experimental animals altogether. These approaches involve use of in silico methods/computerized techniques/software and in vitro methods like cell and tissue culture testing, as well as relative replacement methods by use of invertebrates like nematode worms, fruit flies and microorganisms in place of vertebrates and higher animals [ 1 ]. Examples of proper application of these first “3R2 principles are the use of alternative sources of blood, the exploitation of commercially used animals for scientific research, a proper training without use of animals and the use of specimen from previous experiments for further researches [ 64-67 ].

The fourth “R”, Responsibility refers to concerns around promoting animal welfare by improvements in experimental animals’ social life, development of advanced scientific methods for objectively determining sentience, consciousness, experience of pain and intelligence in the animal kingdom, as well as effective involvement in the professionalization of the public discussion on animal ethics [ 68 ].

OTHER ASPECTS OF ANIMAL RESEARCH ETHICS

Other research ethics considerations include having a clear rationale and reasoning for the use of animals in a research project. Researchers must have reasonable expectation of generating useful data from the proposed experiment. Moreover, the research study should be designed in such a way that it should involve the lowest possible sample size of experimental animals while producing statistically significant results [ 35 ].

All individual researchers that handle experimental animals should be properly trained for handling the particular species involved in the research study. The animal’s pain, suffering and discomfort should be minimized [ 69 ]. Animals should be given proper anesthesia when required and surgical procedures should not be repeated on same animal whenever possible [ 69 ]. The procedure of humane handling and care of experimental animals should be explicitly detailed in the research study protocol. Moreover, whenever required, aseptic techniques should be properly followed [ 70 ]. During the research, anesthetization and surgical procedures on experimental animals should only be performed by professionally skilled individuals [ 69 ].

The Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines that are issued by the National Center for the Replacement, Refinement, and Reduction of Animals in Research (NC3Rs) are designed to improve the documentation surrounding research involving experimental animals [ 70 ]. The checklist provided includes the information required in the various sections of the manuscript i.e. study design, ethical statements, experimental procedures, experimental animals and their housing and husbandry, and more [ 70 ].

It is critical to follow the highest ethical standards while performing animal experiments. Indeed, most of the journals refuse to publish any research data that lack proper ethical considerations [ 35 ].

INVESTIGATORS’ ETHICS

Since animals have sensitivity level similar to the human beings in terms of pain, anguish, survival instinct and memory, it is the responsibility of the investigator to closely monitor the animals that are used and identify any sign of distress [ 71 ]. No justification can rationalize the absence of anesthesia or analgesia in animals that undergo invasive surgery during the research [ 72 ]. Investigators are also responsible for giving high-quality care to the experimental animals, including the supply of a nutritious diet, easy water access, prevention of and relief from any pain, disease and injury, and appropriate housing facilities for the animal species [ 73 ]. A research experiment is not permitted if the damage caused to the animal exceeds the value of knowledge gained by that experiment. No scientific advancement based on the destruction and sufferings of another living being could be justified. Besides ensuring the welfare of animals involved, investigators must also follow the applicable legislation [ 74 , 75 ].

To promote the comfort of experimental animals in England, an animal protection society named: ‘The Society for the Preservation of Cruelty to Animals’ (now the Royal Society for the Prevention of Cruelty to Animals) was established (1824) that aims to prevent cruelty to animal [ 76 ].

ANIMAL WELFARE LAWS

Legislation for animal protection during research has long been established. In 1876 the British Parliament sanctioned the ‘Cruelty to Animals Act’ for animal protection. Russell and Burch (1959) presented the ‘3 Rs’ principles: Replacement, Reduction and Refinement, for use of animals during research [ 61 ]. Almost seven years later, the U.S.A also adopted regulations for the protection of experimental animals by enacting the Laboratory Animal Welfare Act of 1966 [ 60 ]. In Brazil, the Arouca Law (Law No. 11,794/08) regulates the animal use in scientific research experiments [ 76 ].

These laws define the breeding conditions, and regulate the use of animals for scientific research and teaching purposes. Such legal provisions control the use of anesthesia, analgesia or sedation in experiments that could cause distress or pain to experimental animals [ 59 , 76 ]. These laws also stress the need for euthanasia when an experiment is finished, or even during the experiment if there is any intense suffering for the experimental animal [ 76 ].

Several national and international organizations have been established to develop alternative techniques so that animal experimentation can be avoided, such as the UK-based National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) ( www.caat.jhsph.edu ), the European Centre for the Validation of Alternative Methods (ECVAM) [ 77 ], the Universities Federation for Animal Welfare (UFAW) ( www.ufaw.org.uk ), The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) [ 78 ], and The Center for Alternatives to Animal Testing (CAAT) ( www.caat.jhsph.edu ). The Brazilian ‘Arouca Law’ also constitutes a milestone, as it has created the ‘National Council for the Control of Animal Experimentation’ (CONCEA) that deals with the legal and ethical issues related to the use of experimental animals during scientific research [ 76 ].

Although national as well as international laws and guidelines have provided basic protections for experimental animals, the current regulations have some significant discrepancies. In the U.S., the Animal Welfare Act excludes rats, mice and purpose-bred birds, even though these species comprise almost 90% of the animals that are used for research purpose [ 79 ]. On the other hand, certain cats and dogs are getting special attention along with extra protection. While the U.S. Animal Welfare Act ignores birds, mice and rats, the U.S. guidelines that control research performed using federal funding ensure protections for all vertebrates [ 79 , 80 ].

Living conditions of animals

Choice of the animal model.

Based on all the above laws and regulations and in line with the deliberations of ethical committees, every researcher must follow certain rules when dealing with animal models.

Before starting any experimental work, thorough research should be carried out during the study design phase so that the unnecessary use of experimental animals is avoided. Nevertheless, certain research studies may have compelling reasons for the use of animal models, such as the investigation of human diseases and toxicity tests. Moreover, animals are also widely used in the training of health professionals as well as in training doctors in surgical skills [ 1 , 81 ].

Researcher should be well aware of the specific traits of the animal species they intend to use in the experiment, such as its developmental stages, physiology, nutritional needs, reproductive characteristics and specific behaviors. Animal models should be selected on the basis of the study design and the biological relevance of the animal [ 1 ].

Typically, in early research, non-mammalian models are used to get rapid insights into research problems such as the identification of gene function or the recognition of novel therapeutic options. Thus, in biomedical and biological research, among the most commonly used model organisms are the Zebrafish, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans . The main advantage of these non-mammalian animal models is their prolific reproducibility along with their much shorter generation time. They can be easily grown in any laboratory setting, are less expensive than the murine animal models and are somewhat more powerful than the tissue and cell culture approaches [ 82 ].

Caenorhabditis elegans is a small-sized nematode with a short life cycle and that exists in large populations and is relatively inexpensive to cultivate. Scientists have gathered extensive knowledge of the genomics and genetics of Caenorhabditis elegans ; but Caenorhabditis elegans models, while very useful in some respects, are unable to represent all signaling pathways found in humans. Furthermore, due to its short life cycle, scientists are unable to investigate long term effects of test compounds or to analyze primary versus secondary effects [ 6 ].

Similarly, the fruit fly Drosophila melanogaster has played a key role in numerous biomedical discoveries. It is small in size, has a short life cycle and large population size, is relatively inexpensive to breed, and extensive genomics and genetics information is available [ 6 ]. However, its respiratory, cardiovascular and nervous systems differ considerably from human beings. In addition, its immune system is less developed when compared to vertebrates, which is why effectiveness of a drug in Drosophila melanogaster may not be easily extrapolated to humans [ 83 ].

The Zebrafish ( Danio rerio ) is a small freshwater teleost, with transparent embryos, providing easy access for the observation of organogenesis and its manipulation. Therefore, Zebrafish embryos are considered good animal models for different human diseases like tuberculosis and fetal alcohol syndrome and are useful as neurodevelopmental research models. However, Zebrafish has very few mutant strains available, and its genome has numerous duplicate genes making it impossible to create knockout strains, since disrupting one copy of the gene will not disrupt the second copy of that gene. This feature limits the use of Zebrafish as animal models to study human diseases. Additionally they are rather expensive, have long life cycle, and genomics and genetics studies are still in progress [ 82 , 84 ].

Thus, experimentation on these three animals might not be equivalent to experimentation on mammals. Mammalian animal model are most similar to human beings, so targeted gene replacement is possible. Traditionally, mammals like monkey and mice have been the preferred animal models for biomedical research because of their evolutionary closeness to humans. Rodents, particularly mice and rats, are the most frequently used animal models for scientific research. Rats are the most suitable animal model for the study of obesity, shock, peritonitis, sepsis, cancer, intestinal operations, spleen, gastric ulcers, mononuclear phagocytic system, organ transplantations and wound healing. Mice are more suitable for studying burns, megacolon, shock, cancer, obesity, and sepsis as mentioned previously [ 85 ].

Similarly, pigs are mostly used for stomach, liver and transplantation studies, while rabbits are suitable for the study of immunology, inflammation, vascular biology, shock, colitis and transplantations. Thus, the choice of experimental animal mainly depends upon the field of scientific research under consideration [ 1 ].

HOUSING AND ENVIRONMENTAL ENRICHMENT

Researchers should be aware of the environment and conditions in which laboratory animals are kept during research, and they also need to be familiar with the metabolism of the animals kept in vivarium, since their metabolism can easily be altered by different factors such as pain, stress, confinement, lack of sunlight, etc. Housing conditions alter animal behavior, and this can in turn affect experimental results. By contrast, handling procedures that feature environmental enrichment and enhancement help to decrease stress and positively affect the welfare of the animals and the reliability of research data [ 74 , 75 ].

In animals, distress- and agony-causing factors should be controlled or eliminated to overcome any interference with data collection as well as with interpretation of the results, since impaired animal welfare leads to more animal usage during experiment, decreased reliability and increased discrepancies in results along with the unnecessary consumption of animal lives [ 86 ].

To reduce the variation or discrepancies in experimental data caused by various environmental factors, experimental animals must be kept in an appropriate and safe place. In addition, it is necessary to keep all variables like humidity, airflow and temperature at levels suitable for those species, as any abrupt variation in these factors could cause stress, reduced resistance and increased susceptibility to infections [ 74 ].

The space allotted to experimental animals should permit them free movement, proper sleep and where feasible allow for interaction with other animals of the same species. Mice and rats are quite sociable animals and must, therefore, be housed in groups for the expression of their normal behavior. Usually, laboratory cages are not appropriate for the behavioral needs of the animals. Therefore, environmental enrichment is an important feature for the expression of their natural behavior that will subsequently affect their defense mechanisms and physiology [ 87 ].

The features of environmental enrichment must satisfy the animals’ sense of curiosity, offer them fun activities, and also permit them to fulfill their behavioral and physiological needs. These needs include exploring, hiding, building nests and gnawing. For this purpose, different things can be used in their environment, such as PVC tubes, cardboard, igloos, paper towel, cotton, disposable masks and paper strips [ 87 ].

The environment used for housing of animals must be continuously controlled by appropriate disinfection, hygiene protocols, sterilization and sanitation processes. These steps lead to a reduction in the occurrence of various infectious agents that often found in vivarium, such as Sendai virus, cestoda and Mycoplasma pulmonis [ 88 ].

Euthanasia is a term derived from Greek, and it means a death without any suffering. According to the Brazilian Arouca Law (Article 14, Chapter IV, Paragraphs 1 and 2), an animal should undergo euthanasia, in strict compliance with the requirements of each species, when the experiment ends or during any phase of the experiment, wherever this procedure is recommended and/or whenever serious suffering occurs. If the animal does not undergo euthanasia after the intervention it may leave the vivarium and be assigned to suitable people or to the animal protection bodies, duly legalized [ 1 ].

Euthanasia procedures must result in instant loss of consciousness which leads to respiratory or cardiac arrest as well as to complete brain function impairment. Another important aspect of this procedure is calm handling of the animal while taking it out of its enclosure, to reduce its distress, suffering, anxiety and fear. In every research project, the study design should include the details of the appropriate endpoints of these experimental animals, and also the methods that will be adopted. It is important to determine the appropriate method of euthanasia for the animal being used. Another important point is that, after completing the euthanasia procedure, the animal’s death should be absolutely confirmed before discarding their bodies [ 87 , 89 ].

Relevance of animal experimentations and possible alternatives

Relevance of animal experiments and their adverse effects on human health.

One important concern is whether human diseases, when inflicted on experimental animals, adequately mimic the progressions of the disease and the treatment responses observed in humans. Several research articles have made comparisons between human and animal data, and indicated that the results of animals’ research could not always be reliably replicated in clinical research among humans. The latest systematic reviews about the treatment of different clinical conditions including neurology, vascular diseases and others, have established that the results of animal studies cannot properly predict human outcomes [ 59 , 90 ].

At present, the reliability of animal experiments for extrapolation to human health is questionable. Harmful effects may occur in humans because of misleading results from research conducted on animals. For instance, during the late fifties, a sedative drug, thalidomide, was prescribed for pregnant women, but some of the women using that drug gave birth to babies lacking limbs or with foreshortened limbs, a condition called phocomelia. When thalidomide had been tested on almost all animal models such as rats, mice, rabbits, dogs, cats, hamsters, armadillos, ferrets, swine, guinea pig, etc., this teratogenic effect was observed only occasionally [ 91 ]. Similarly, in 2006, the compound TGN 1412 was designed as an immunomodulatory drug, but when it was injected into six human volunteer, serious adverse reactions were observed resulting from a deadly cytokine storm that in turn led to disastrous systemic organ failure. TGN 1412 had been tested successfully in rats, mice, rabbits, and non-human primates [ 92 ]. Moreover, Bailey (2008) reported 90 HIV vaccines that had successful trial results in animals but which failed in human beings [ 93 ]. Moreover, in Parkinson disease, many therapeutic options that have shown promising results in rats and non-human primate models have proved harmful in humans. Hence, to analyze the relevance of animal research to human health, the efficacy of animal experimentation should be examined systematically [ 94 , 95 ]. At the same time, the development of hyperoxaluria and renal failure (up to dialysis) after ileal-jejunal bypass was unexpected because this procedure was not preliminarily evaluated on an animal model [ 96 ].

Several factors play a role in the extrapolation of animal-derived data to humans, such as environmental conditions and physiological parameters related to stress, age of the experimental animals, etc. These factors could switch on or off genes in the animal models that are specific to species and/or strains. All these observations challenge the reliability and suitability of animal experimentation as well as its objectives with respect to human health [ 76 , 92 ].

ALTERNATIVE TO ANIMAL EXPERIMENTATION/DEVELOPMENT OF NEW PRODUCTS AND TECHNIQUES TO AVOID ANIMAL SACRIFICE IN RESEARCH

Certainly, in vivo animal experimentation has significantly contributed to the development of biological and biomedical research. However it has the limitations of strict ethical issues and high production cost. Some scientists consider animal testing an ineffective and immoral practice and therefore prefer alternative techniques to be used instead of animal experimentation. These alternative methods involve in vitro experiments and ex vivo models like cell and tissue cultures, use of plants and vegetables, non-invasive human clinical studies, use of corpses for studies, use of microorganisms or other simpler organism like shrimps and water flea larvae, physicochemical techniques, educational software, computer simulations, mathematical models and nanotechnology [ 97 ]. These methods and techniques are cost-effective and could efficiently replace animal models. They could therefore, contribute to animal welfare and to the development of new therapies that can identify the therapeutics and related complications at an early stage [ 1 ].

The National Research Council (UK) suggested a shift from the animal models toward computational models, as well as high-content and high-throughput in vitro methods. Their reports highlighted that these alternative methods could produce predictive data more affordably, accurately and quickly than the traditional in vivo or experimental animal methods [ 98 ].

Increasingly, scientists and the review boards have to assess whether addressing a research question using the applied techniques of advanced genetics, molecular, computational and cell biology, and biochemistry could be used to replace animal experiments [ 59 ]. It must be remembered that each alternative method must be first validated and then registered in dedicated databases.

An additional relevant concern is how precisely animal data can mirror relevant epigenetic changes and human genetic variability. Langley and his colleagues have highlighted some of the examples of existing and some emerging non-animal based research methods in the advanced fields of neurology, orthodontics, infectious diseases, immunology, endocrine, pulmonology, obstetrics, metabolism and cardiology [ 99 ].

IN SILICO SIMULATIONS AND INFORMATICS

Several computer models have been built to study cardiovascular risk and atherosclerotic plaque build-up, to model human metabolism, to evaluate drug toxicity and to address other questions that were previously approached by testing in animals [ 100 ].

Computer simulations can potentially decrease the number of experiments required for a research project, however simulations cannot completely replace laboratory experiments. Unfortunately, not all the principles regulating biological systems are known, and computer simulation provide only an estimation of possible effects due to the limitations of computer models in comparison with complex human tissues. However, simulation and bio-informatics are now considered essential in all fields of science for their efficiency in using the existing knowledge for further experimental designs [ 76 ].

At present, biological macromolecules are regularly simulated at various levels of detail, to predict their response and behavior under certain physical conditions, chemical exposures and stimulations. Computational and bioinformatic simulations have significantly reduced the number of animals sacrificed during drug discovery by short listing potential candidate molecules for a drug. Likewise, computer simulations have decreased the number of animal experiments required in other areas of biological science by efficiently using the existing knowledge. Moreover, the development of high definition 3D computer models for anatomy with enhanced level of detail, it may make it possible to reduce or eliminate the need for animal dissection during teaching [ 101 , 102 ].

3D CELL-CULTURE MODELS AND ORGANS-ON-CHIPS

In the current scenario of rapid advancement in the life sciences, certain tissue models can be built using 3D cell culture technology. Indeed, there are some organs on micro-scale chip models used for mimicking the human body environment. 3D models of multiple organ systems such as heart, liver, skin, muscle, testis, brain, gut, bone marrow, lungs and kidney, in addition to individual organs, have been created in microfluidic channels, re-creating the physiological chemical and physical microenvironments of the body [ 103 ]. These emerging techniques, such as the biomedical/biological microelectromechanical system (Bio-MEMS) or lab-on-a-chip (LOC) and micro total analysis systems (lTAS) will, in the future, be a useful substitute for animal experimentation in commercial laboratories in the biotechnology, environmental safety, chemistry and pharmaceutical industries. For 3D cell culture modeling, cells are grown in 3D spheroids or aggregates with the help of a scaffold or matrix, or sometimes using a scaffold-free method. The 3D cell culture modeling conditions can be altered to add proteins and other factors that are found in a tumor microenvironment, for example, or in particular tissues. These matrices contain extracellular matrix components such as proteins, glycoconjugates and glycosaminoglycans that allow for cell communication, cell to cell contact and the activation of signaling pathways in such a way that the morphological and functional differentiation of these cells can accurately mimic their environment in vivo . This methodology, in time, will bridge the gap between in vivo and in vitro drug screening, decreasing the utilization of animal models during research [ 104 ].

ALTERNATIVES TO MICROBIAL CULTURE MEDIA AND SERUM-FREE ANIMAL CELL CULTURES

There are moves to reduce the use of animal derived products in many areas of biotechnology. Microbial culture media peptones are mostly made by the proteolysis of farmed animal meat. However, nowadays, various suppliers provide peptones extracted from yeast and plants. Although the costs of these plant-extracted peptones are the same as those of animal peptones, plant peptones are more environmentally favorable since less plant material and water are required for them to grow, compared with the food grain and fodder needed for cattle that are slaughtered for animal peptone production [ 105 ].

Human cell culture is often carried out in a medium that contains fetal calf serum, the production of which involves animal (cow) sacrifice or suffering. In fact, living pregnant cows are used and their fetuses removed to harvest the serum from the fetal blood. Fetal calf serum is used because it is a natural medium rich in all the required nutrients and significantly increases the chances of successful cell growth in culture. Scientists are striving to identify the factors and nutrients required for the growth of various types of cells, with a view to eliminating the use of calf serum. At present, most cell lines could be cultured in a chemically-synthesized medium without using animal products. Furthermore, data from chemically-synthesized media experiments may have better reproducibility than those using animal serum media, since the composition of animal serum does change from batch to batch on the basis of animals’ gender, age, health and genetic background [ 76 ].

ALTERNATIVES TO ANIMAL-DERIVED ANTIBODIES

Animal friendly affinity reagents may act as an alternative to antibodies produced, thereby removing the need for animal immunization. Typically, these antibodies are obtained in vitro by yeast, phage or ribosome display. In a recent review, a comparative analysis between animal friendly affinity reagents and animal derived-antibodies showed that the affinity reagents have superior quality, are relatively less time consuming, have more reproducibility and are more reliable and are cost-effective [ 106 , 107 ].

Conclusions

Animal experimentation led to great advancement in biological and biomedical sciences and contributed to the discovery of many drugs and treatment options. However, such experimentation may cause harm, pain and distress to the animals involved. Therefore, to perform animal experimentations, certain ethical rules and laws must be strictly followed and there should be proper justification for using animals in research projects. Furthermore, during animal experimentation the 4 Rs principles of reduction, refinement, replacement and responsibility must be followed by the researchers. Moreover, before beginning a research project, experiments should be thoroughly planned and well-designed, and should avoid unnecessary use of animals. The reliability and reproducibility of animal experiments should also be considered. Whenever possible, alternative methods to animal experimentation should be adopted, such as in vitro experimentation, cadaveric studies, and computer simulations.

While much progress has been made on reducing animal experimentation there is a need for greater awareness of alternatives to animal experiments among scientists and easier access to advanced modeling technologies. Greater research is needed to define a roadmap that will lead to the elimination of all unnecessary animal experimentation and provide a framework for adoption of reliable alternative methodologies in biomedical research.

Acknowledgements

This research was funded by the Provincia Autonoma di Bolzano in the framework of LP 15/2020 (dgp 3174/2021).

Conflicts of interest statement

Authors declare no conflict of interest.

Author's contributions

MB: study conception, editing and critical revision of the manuscript; AKK, DP, GH, RB, Paul S, Peter S, RM, BF, NC, SM, LL, DD, GMT, MCE, MD, SM, Daniele M, GB, AD, KD, MCM, TB, MS, STC, Donald M, AM, AB, KLH, MK, LS, LL, GF: literature search, editing and critical revision of the manuscript. All authors have read and approved the final manuscript.

Contributor Information

INTERNATIONAL BIOETHICS STUDY GROUP : Derek Pheby , Gary Henehan , Richard Brown , Paul Sieving , Peter Sykora , Robert Marks , Benedetto Falsini , Natale Capodicasa , Stanislav Miertus , Lorenzo Lorusso , Gianluca Martino Tartaglia , Mahmut Cerkez Ergoren , Munis Dundar , Sandro Michelini , Daniele Malacarne , Tommaso Beccari , Michele Samaja , Matteo Bertelli , Donald Martin , Assunta Morresi , Ariola Bacu , Karen L. Herbst , Mykhaylo Kapustin , Liborio Stuppia , Ludovica Lumer , and Giampietro Farronato

Ethical care for research animals

WHY ANIMAL RESEARCH?

The use of animals in some forms of biomedical research remains essential to the discovery of the causes, diagnoses, and treatment of disease and suffering in humans and in animals., stanford shares the public's concern for laboratory research animals..

Many people have questions about animal testing ethics and the animal testing debate. We take our responsibility for the ethical treatment of animals in medical research very seriously. At Stanford, we emphasize that the humane care of laboratory animals is essential, both ethically and scientifically.  Poor animal care is not good science. If animals are not well-treated, the science and knowledge they produce is not trustworthy and cannot be replicated, an important hallmark of the scientific method .

There are several reasons why the use of animals is critical for biomedical research: 

••  Animals are biologically very similar to humans. In fact, mice share more than 98% DNA with us!

••  Animals are susceptible to many of the same health problems as humans – cancer, diabetes, heart disease, etc.

••  With a shorter life cycle than humans, animal models can be studied throughout their whole life span and across several generations, a critical element in understanding how a disease processes and how it interacts with a whole, living biological system.

The ethics of animal experimentation

Nothing so far has been discovered that can be a substitute for the complex functions of a living, breathing, whole-organ system with pulmonary and circulatory structures like those in humans. Until such a discovery, animals must continue to play a critical role in helping researchers test potential new drugs and medical treatments for effectiveness and safety, and in identifying any undesired or dangerous side effects, such as infertility, birth defects, liver damage, toxicity, or cancer-causing potential.

U.S. federal laws require that non-human animal research occur to show the safety and efficacy of new treatments before any human research will be allowed to be conducted.  Not only do we humans benefit from this research and testing, but hundreds of drugs and treatments developed for human use are now routinely used in veterinary clinics as well, helping animals live longer, healthier lives.

It is important to stress that 95% of all animals necessary for biomedical research in the United States are rodents – rats and mice especially bred for laboratory use – and that animals are only one part of the larger process of biomedical research.

Our researchers are strong supporters of animal welfare and view their work with animals in biomedical research as a privilege.

Stanford researchers are obligated to ensure the well-being of all animals in their care..

Stanford researchers are obligated to ensure the well-being of animals in their care, in strict adherence to the highest standards, and in accordance with federal and state laws, regulatory guidelines, and humane principles. They are also obligated to continuously update their animal-care practices based on the newest information and findings in the fields of laboratory animal care and husbandry.  

Researchers requesting use of animal models at Stanford must have their research proposals reviewed by a federally mandated committee that includes two independent community members.  It is only with this committee’s approval that research can begin. We at Stanford are dedicated to refining, reducing, and replacing animals in research whenever possible, and to using alternative methods (cell and tissue cultures, computer simulations, etc.) instead of or before animal studies are ever conducted.

Organizations and Resources

There are many outreach and advocacy organizations in the field of biomedical research.

• Learn more about outreach and advocacy organizations

Stanford Discoveries

What are the benefits of using animals in research? Stanford researchers have made many important human and animal life-saving discoveries through their work. 

• Learn more about research discoveries at Stanford

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Is Animal Testing Ever Justified?

The E.P.A. recently said it would move away from requiring the testing of potentially harmful chemicals on animals. Do you support the decision?

By Natalie Proulx

Find all our Student Opinion questions here.

On Sept. 10, the Environmental Protection Agency said it would move away from requiring the testing of potentially harmful chemicals on animals, a decision that was hailed by animal rights groups but criticized by environmentalists and researchers who said the practice was necessary to rigorously safeguard human health.

What are your thoughts on animal testing? Do you think it is ever justified? Why or why not?

In “ E.P.A. Says It Will Drastically Reduce Animal Testing ,” Mihir Zaveri, Mariel Padilla and Jaclyn Peiser write about the decision:

The E.P.A. Administrator Andrew Wheeler said the agency plans to reduce the amount of studies that involve mammal testing by 30 percent by 2025, and to eliminate the studies entirely by 2035, though some may still be approved on a case-by-case basis. The agency said it would also invest $4.25 million in projects at four universities and a medical center that are developing alternate ways of testing chemicals that do not involve animals. “We can protect human health and the environment by using cutting-edge, ethically sound science in our decision-making that efficiently and cost-effectively evaluates potential effects without animal testing,” Mr. Wheeler said in a memo announcing the changes. The E.P.A. has for decades required testing on a variety of animals — including rats, dogs, birds and fish — to gauge their toxicity before the chemicals can be bought, sold or used in the environment.

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Animal Testing: History and Arguments Essay

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In general, animal testing is allowed all over the world. Some countries impose certain restrictions on that matter, some – do not introduce any restrictions at all. However, even those countries that have certain laws prohibiting tests on animals do not take into account the fact that animals are living creatures and must not suffer for the sake of an experiment. Moreover, in most facilities and laboratories, animals are kept in cages, thereby having absolutely no freedom. Most of the experiments performed on animals bring them suffering, lead to disability, and even death. This inhumane treatment of animals does not justify any cause (Haugen, 2000). Thus, the main reason why these experiments must be stopped is that, according to the statistics, the majority of them are ineffective and inaccurate.

History of Animal Testing

Animal testing has a long history. Considering the fact that animals are living creatures, medical experiments on them were already conducted at least three thousand years ago. The first records mentioning the experiments on animals date back to the fourth century BCE in Ancient Greece (Murnaghan, 2017). Thus, in ancient times, it was a widely adopted practice to perform dissections of animals in order to understand how to make surgical operations on humans.

Since the 18 th century, with the development of medicine, the frequency of animal testing has significantly increased. Moreover, if a couple of centuries ago, there were only single experiments that were performed by separate scientists, now, it has developed into the large industry that catches animals in the wild and uses them as guinea pigs (Scutti, 2013). Thus, although there are many innovative technologies that can serve as better alternatives to animal testing, people are still reluctant to change the current state of affairs.

Despite animal testing being rather an old practice, ethical considerations on that matter also occurred quite a long time ago (Scutti, 2013). For example, in the 17 th century, a psychologist Edmund O’Meara stated that animal testing was unnecessary, as it often gave inaccurate results. In this respect, he provided an example regarding vivisection that, as he claimed, placed the body of an animal in an unnatural state, in which it endured a lot of pain that was both cruel and gave false results.

The first animal protection law was established in Great Britain in 1822. A significant milestone in the history of animal protection legislation was the introduction of the Cruelty to Animals Act in 1876 in Great Britain. This law was promoted by Charles Darwin who, despite being a biologist and a scientist, was against vivisection. In the 1860s, the movements against animal testing occurred in the USA. As a result, Henry Bergh established the American Society for the Prevention of Cruelty to Animals (ASPCA) in 1866. After that, the American Anti-Vivisection Society (AAVS) was founded in 1883 (Haugen, 2000). Thus, the end of the 19 th century was the time when many articles were written, and campaigns were started calling for terminating the experiments on animals.

However, at the beginning of the 20 th century, the tendency of releasing laws about animal protection changed. Unfortunately, the efforts of antivivisectionists to promote their campaigns to make the US government to ban animal testing failed due to the overall support of such experiments by the public, which was assured by the organizations who performed these experiments that animals were kept in good conditions, bred well, and injected with anaesthetics in those operations that could cause them much pain. Therefore, only in the 1960s, the efforts of antivivisectionists were partially justified, with the release of the Laboratory Animal Welfare Act in 1966 (Haugen, 2000). Nevertheless, that law was more focused on the welfare of animals in laboratories rather than on the prohibition of animal testing.

Nowadays, there are a great number of organizations that advocate for stopping using animals in the experiments. Although the overall effectiveness of their campaigns is quite low, they have managed to achieve some positive results concerning the problem of animal testing (Murnaghan, 2017). Additionally, considering the current tendency of the active development of various technologies that can easily substitute experiments on animals, there is hope that soon the animal testing industry will cease to exist.

Animal Testing Is Cruel

The first argument against animal testing is that it is simply cruel. People must understand that animals are the same living creature as them and can feel both psychological and physical pain in the same way as humans. Thus, in the case of experimenting on animals, the ethical and humane aspects of the issue must prevail and give people a stimulus to seek for other ways of studying diseases that can be much better.

Animal Testing and Its Types

First of all, it is necessary to describe the types of animal testing in order to understand the degree of the cruelty of these experiments. In general, animal testing is the process of experimenting on animals where they usually undergo various medical procedures which cause them suffering or even death. These experiments are usually aimed at finding a cure to some disease that humans and certain animals have in common or at exploring how a biological organism works. During the experiments, scientists usually keep animals in cages and use them in laboratories where they harm them on purpose (“What is animal testing,” 2016). Moreover, there are certain kinds of experiments that cause animals a lot of pain, and, in many of them, animals die.

The most common type of an experiment on animals is feeding them with certain substances and injecting them with experimental medications. After the procedure is completed, scientists observe the effects that these substances have caused. In fact, the result is often unpredictable, and animals can die a horrible death with much pain. Another type of experiments is exposing animals to toxic substances and radiation. These experiments are primarily aimed at discovering the effects that radiation and certain chemicals can have on a biological body. Similarly, such experiments make animals suffer (“What is animal testing,” 2016). Moreover, if animals survive after such experiments, the damage that radiation and chemicals have caused to them is often permanent, and they will live the rest of their lives suffering.

One more type of experiments on animals is dissecting animals while they are still alive. Certainly, during this operation, they are under anesthetics, but it does not justify the result that they get after the procedure is completed. The main reason for these experiments is to find out how the internal parts of the biological body work. This operation usually involves removing internal organs, pumping out blood, and excising parts of tissues, which makes animals cripples afterwards. Additionally, there is one more type of an experiment that is usually practiced in laboratories. This is a psychological experiment that involves placing animals in situations and conditions which cause them to feel fear, anxiety, or depression. Such experiments are usually aimed at identifying the principles of animals’ behavior and comparing it to that of humans (“The five worst animal experiments,” 2014). Nevertheless, after these experiments, animals usually become very aggressive and cannot normally function in their animal “society”.

Laws and Animal Testing

According to most religious laws, animal testing is forbidden, as they are defined as the same creatures as humans. Certainly, animals are not as smart as humans, and their perception of reality is different, but they have similar bodies and experience similar feelings. Therefore, before making horrible experiments on animals, humans must think what it would be like if they were experimented on (“The Muslim view on animal,” 2017). Thus, animals have the same right to live their full lives as humans.

Although human laws impose a certain restriction regarding the experiments on animals, they are not enough, as they still allow people to torture them in the experiments. According to European legislation, all vertebrate animals including reptiles, fish, birds, and mammals and only some invertebrates such as octopuses are considered “animals”, on which it is prohibited to experiment (“Treatment of animals,” 2016). In the USA, the situation is worse and such creatures as mice, amphibians, birds, fish, and rats are not defined as “animals”, and scientists can freely perform any experiments on them that they want.

The system of experimenting on animals has grown into a multi-million dollar industry that has many facilities and laboratories around the world. They also have special facilities aimed at breeding animals specifically for testing. In these facilities, animals usually live in bad conditions being imprisoned and forcibly fed. Using wild-caught animals is prohibited in Europe and in some other countries, but it is allowed in other countries of the world. It is usually forbidden to use such domestic animals as dogs and cats in experiments, but, unfortunately, not in all countries (McKay, 2016). Even monkeys that resemble humans the most are often used in experiments.

In terms of animal suffering, The EU even introduced a scale which measures the degree of suffering experienced by animals in a particular experiment. Thus, they distinguish between “minor”, “moderate”, and “severe” suffering inflicted on animals. For example, in 2012, in the UK, more than 60% of permissions were granted by the British government allowing animals to be undergone from moderate to severe suffering. Reportedly, approximately 75% of the experiments were performed without injecting the animals with anesthetics. Moreover, quite a big percentage of those experiments required animals to die (Scheler, 2017). For instance, the tests for various vaccines and chemicals resulted in the death of more than 50% of the animals involved in these experiments.

Animal Testing Is Ineffective

The second argument against animal testing is that it is often ineffective, as the results received from the experiments can be inaccurate. There are many reasons for this, but, the most important point is that in such science as medicine, the information must be reliable; otherwise, there is always a risk that a particular medicine will cause unpleasant effects in humans or even be life-threatening.

Examples of the Ineffectiveness of Animal Testing

In addition to being cruel and inhumane, the experiments on animals often turn out to be ineffective. The main reason for this is that the animal organism either responds differently to many life-threatening diseases that humans suffer from or is completely immune to them. For example, animals do not suffer from most heart diseases, some types of cancer and HIV, they do not have Parkinson’s disease and the majority of psychiatric diseases such as schizophrenia. However, some of these diseases can be artificially induced in them for the sake of an experiment that allegedly shows how these diseases can be cured in humans. Thus, the most important argument is that in these experiments, people usually do not take into consideration other factors that are inherent only in humans and affect the behavior of diseases (“Cruelty to animals,” 2017). These factors include socio-economic conditions, genetics, psychological issues, and personal experience.

Indeed, according to the statistics, quite a great number of experiments on animals, that were promising in terms of finding a cure to some diseases, turned out to be ineffective for humans. In this respect, the end does not justify the means, as animals suffered for nothing. As a result, animals’ lives along with the time and money were wasted, and no effective treatment was developed (“Arguments against animal,” 2016). In addition, as it can be seen, after the decades of animal testing aimed at finding a cure for Alzheimer’s disease, stroke, AIDS, Parkinson’s disease, diabetes, and cancer, there is still no reliable cure and effective treatment for them.

Thus, according to the statistics, the majority of experiments on animals that show promising results, turn out to be ineffective when it comes to humans. Moreover, the experimenting on smaller animals such as rabbits, mice, and rats showed an even lower rate of success, primarily because their organisms differ from that of a human (Scheler, 2017). Additionally, statistics show that only 20% of experimental drugs used on animals are effective in humans. In terms of testing the safety of drugs, only 45% of experiments work for humans.

According to the overall results of the experiments on animals conducted all over the world, approximately 120 million animals are used in them, and only about 30 new medications are approved every year, which is far from being efficient. The investment of the U.S. drug industry in the experiments equals $50 billion each year, but the approval rate has not changed since the 1960s. Among those drugs that are approved, not all of them are completely effective for everyone due to different individual reactions (McKay, 2016). Overall, for the last 20 years, only five percent of experiments performed on animals resulted in a successful approval of treatments.

Sometimes, animal testing can be dangerous even for humans. A vivid example is a drug called Vioxx that was used for arthritis. After successful experiments on monkeys and on some other mammals, this drug was approved for human usage. However, Vioxx turned out to be dangerous for humans causing more than 300,000 heart attacks all over the world, almost half of which resulted in the lethal outcome. Another example is fialuridine, a Hepatitis B drug that was prohibited for having caused liver damage resulting in five deaths. However, this drug had been several times tested on animals before. One more illustrative example is a monoclonal antibody treatment (TGN1412) that was tested on human volunteers. As a result, it caused an allergic reaction, after which the volunteers were hospitalized (Haugen, 2000). However, this drug had been used on monkeys several hundred times before, and no side effects were identified.

Alternatives to Animal Testing

Banning animal testing does not necessarily mean that the development of medications that can provide treatment for incurable diseases will stop, as there are always alternatives, which can improve progress in medicine and add humaneness to the science. Thus, with technological developments in the sphere of science, the number of alternatives to animal testing is increasing. In this respect, the main problem is that most people are reluctant to use new technologies (“Animal testing 101,” 2016). Instead, they tend to stick to more conservative and traditional methods that certainly involve animal testing.

Another obstacle in the process of adoption of these new methods is bureaucracy. There are a lot of organizations and charities that advocate for the prohibition of animal testing, and they can accelerate the process of implementation of these innovations.

In terms of the alternatives, there are several of them that are very effective. The first alternative is growing cells and other organic material in laboratories. Nowadays, almost any type of a human cell can be created in a laboratory. These cells are used in the creation of special devices that are called “organs-on-chips”. These devices can be used for experiments instead of animals. There were already several successful experiments conducted on these devices that involved observing the behavior of diseases and the effects of drugs (“Alternatives to animal,” 2016). Additionally, cell cultures are now the primary focus regarding the development of treatment to such diseases as cancer, AIDS, kidney diseases, and sepsis.

Another alternative to animal testing, which is not new though, is human tissues. Human tissues that can be provided by volunteers or extracted from dead bodies can be used in some kinds of experiments. Moreover, there are many operations such as cosmetic surgery, biopsy, and transplants that can serve as a reliable source of human tissues. Using brain tissues from dead bodies has also lead to a better understanding of such diseases as Parkinson’s disease or multiple sclerosis.

One more alternative to animal testing, the importance of which has been increasingly growing for the past several decades, is computer models. Indeed, the most powerful contemporary computers in the world are able to simulate many processes that would occur in a human body after taking a particular experimental medication. These virtual experiments are primarily based on the already existing data about a particular disease and its behavior in the human body and on mathematical, chemical, and physical laws integrated into this program of simulation (“Alternatives to animal,” 2016). Certainly, now, computer sphere is not powerful enough for complex virtual experiments, but taking into account the rate of its growth, it will be soon.

Arguments for Animal Testing

Despite all the evidence listed above and showing that animal testing is both a cruel and ineffective practice, it still has its defenders. For example, the IQ Consortium DruSafe argues that nonclinical animal testing is crucial when it comes to assessing the risks of developing new drugs (Mangipudy, 2014). They believe that there are no in vitro or in silico systems developed enough to accurately emulate all of the complexities of the human organism (Mangipudy, 2014). Further, even with the eventual development of these surrogate systems, their ability to predict all of the negative effects from unique toxicities is still under question. In general, many people, while denouncing animal testing for cosmetic purposes, still insist that it is an unavoidable necessity for improving human health. Just as well, many people consider animal testing to be a necessary evil – they agree about it being cruel while saying that without it there would be no treatments like insulin, vaccines, HIV drugs and so on and that it helped us get better understanding of diseases like malaria or hemophilia (Murnaghan, 2017).

While it is true that animal testing has proven to be useful in the past, it does not mean that we need to stop developing new methods of testing and keep it around animals. If we consider ourselves to be a truly evolved species, we need to abandon any sort of animal cruelty completely and find ways to benefit ourselves without causing harm to anyone or anything. Furthermore, the effectiveness of alternative methods of testing is not to be underestimated, considering that more and more of them are being researched and improved with each passing year. These alternatives, both with their quantity and their quality, clearly highlight the obsolescence of animal testing and the need for replacing it with more humane and harmless methods.

Thus, as it can be seen from the statistics, animal testing is cruel and in most cases, not effective. Therefore, it must be banned, especially now, when there are many innovative technologies that can be used as alternatives. Moreover, these alternatives have already shown great promises in being much more efficient than animal testing. Fortunately, the current tendency shows that these alternatives will be adopted in the near future, thereby bringing the end to violent experiments on animals.

Alternatives to animal testing . (2016). Web.

Animal testing 101 . (2016). Web.

Arguments against animal testing . (2016). Web.

Cruelty to animals in laboratories . (2017). Web.

The five worst animal experiments happening right now . (2014). Web.

Harm and suffering . (2017). Web.

Haugen, D. M. (2000). Animal experimentation . San Diego, CA: Greenhaven Press.

McKay, M. (2016). The cruelty of lab animal testing. Web.

Murnaghan, I. (2017). Background and history of animal testing. Web.

The Muslim view on animal testing . (2017). Web.

Scheler, S. (2017). Everything you need to know about animal testing. Web.

Scutti, S. (2013). Animal testing: A long, unpretty history. Web.

Treatment of animals . (2016). Web.

What is animal testing? (2016). Web.

Mangipudy, R., Burkhardt, J., & Kadambi, V. J. (2014). Use of animals for toxicology testing is necessary to ensure patient safety in pharmaceutical development. Regulatory Toxicology and Pharmacology , 70 (2), 439-441.

Murnaghan, I. (2017). Using Animals for Testing: Pros Versus Cons. Web.

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Essay on Why Animal Testing Should Be Banned

Students are often asked to write an essay on Why Animal Testing Should Be Banned in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

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100 Words Essay on Why Animal Testing Should Be Banned

Animal testing is unkind.

Animal testing often causes pain and suffering to animals. They are kept in small cages and are used for experiments that can hurt them. This is not fair because animals feel pain just like we do. We should not make them suffer for our benefits.

Not Always Useful

Many times, tests on animals do not give results that are helpful for humans. This is because animals and humans are different. So, the pain we cause to animals may not even help us in the end.

Better Options Exist

Nowadays, we have other ways to test products that do not involve hurting animals. Scientists can use computer models or grow human cells in labs. These methods can give us good information without causing harm to any living creature.

250 Words Essay on Why Animal Testing Should Be Banned

Animal testing: why it should be banned.

Animal testing refers to scientific experiments using non-human animals as subjects. For many years, animals have been used in experiments to study diseases, test medicines, and explore other scientific questions. However, there are many reasons why this practice should be banned.

Pain and Suffering

Unreliable results.

Animal testing results are often unreliable when applied to humans. Animals may respond differently to drugs and treatments than humans do, leading to inaccurate or misleading findings. Additionally, the stress and fear experienced by animals during testing can affect the results, making them even less reliable.

Alternatives to Animal Testing

Today, there are many alternative methods available that can replace animal testing. These methods include computer simulations, cell cultures, and human tissue models. These alternatives are not only more humane, but they are often more accurate and reliable than animal testing.

Ethical Concerns

Animal testing raises serious ethical concerns. Many people believe that it is wrong to harm or kill animals for the sake of scientific research. Animals are sentient beings who deserve to be treated with respect and compassion.

In light of the pain and suffering caused to animals, the unreliability of results, the availability of alternatives, and the ethical concerns, it is clear that animal testing should be banned. It is time to move towards a more humane and ethical approach to scientific research.

500 Words Essay on Why Animal Testing Should Be Banned

What is animal testing.

Animal testing is the use of animals in experiments and other scientific studies. Animals are used to test products such as medicines, cosmetics, and chemicals, as well as to study diseases and develop new treatments.

Why is Animal Testing Bad?

Animal testing is bad because it causes pain and suffering to animals. Animals are often subjected to painful procedures, such as surgery, injections, and exposure to toxic chemicals. They may also be deprived of food, water, and sleep.

Animals Are Not Like Humans

The results of animal tests are not always accurate because animals are not like humans. They have different bodies, different metabolisms, and different immune systems. This means that drugs and chemicals that are safe for animals may not be safe for humans.

There Are Alternatives to Animal Testing

There are many alternatives to animal testing that are more accurate and humane. These alternatives include computer models, cell cultures, and human tissue samples. These alternatives are often more cost-effective than animal testing and do not cause pain and suffering to animals.

Animal Testing is Cruel and Unnecessary

Animal testing is a cruel and unnecessary practice. There are many alternatives to animal testing that are more accurate and humane. We should ban animal testing and replace it with these alternatives.

Animal testing is a cruel and unnecessary practice. It causes pain and suffering to animals and is often inaccurate. There are many alternatives to animal testing that are more accurate and humane. We should ban animal testing and replace it with these alternatives.

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Home — Essay Samples — Social Issues — Animal Testing — Argumentative Paper: Against Animal Testing

Argumentative Paper: Against Animal Testing

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Published: Feb 7, 2024

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Introduction, ethical concerns, scientific limitations, economic considerations, legal issues, public opinion and activism.

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Animal Testing Essay

Ielts animal testing essay.

Here you will find an example of an IELTS  animal testing essay .

In this essay, you are asked to discuss the arguments  for  and  against  animal testing, and then give  your own conclusions  on the issue.

This means you must look at both sides of the issue and you must also be sure you give your opinion too.

The essay is similar to an essay that says " Discuss both opinions and then give your opinion " but it is worded differently.

Take a look at the question and model answer below, and think about how the essay has been organised and how it achieves coherence and cohesion.

You should spend about 40 minutes on this task.

Write about the following topic:

Examine the arguments in favour of and against animal experiments, and come to a conclusion on this issue.

Give reasons for your answer and include any relevant examples from your own experience or knowledge.

Write at least 250 words.

Animals Testing Essay - Model Answer

Issues related to animal experimentation are frequently discussed these days, particularly in the media. It is often said that animals should not be used in testing because it is cruel and unnecessary. This essay will examine the arguments for and against animal testing. 

On the one hand, the people who support these experiments say that we must do tests on animals. For instance, many famous lifesaving drugs were invented in this way, and animal experiments may help us to find more cures in the future. Indeed, possibly even a cure for cancer and AIDS. Furthermore, the animals which are used are not usually wild but are bred especially for experiments. Therefore, they believe it is not true that animal experiments are responsible for reducing the number of wild animals on the planet. 

On the other hand, others feel that there are good arguments against this. First and foremost, animal experiments are unkind and cause animals a lot of pain. In addition, they feel that many tests are not really important, and in fact animals are not only used to test new medicines but also new cosmetics, which could be tested on humans instead. Another issue is that sometimes an experiment on animals gives us the wrong result because animals’ bodies are not exactly the same as our own. As a consequence, this testing may not be providing the safety that its proponents claim.

In conclusion, I am of the opinion, on balance, that the benefits do not outweigh the disadvantages, and testing on animals should not continue. Although it may improve the lives of humans, it is not fair that animals should suffer in order to achieve this.

(Words 278)

This animal testing essay would achieve a high score.

It fully answers all parts of the task - explaining the arguments ' for ' in the first paragraph and the arguments ' against ' in the next. Conclusions are then drawn with the writer giving their opinion in the conclusion.

It is thus very clearly organised, with each body paragraph having a central idea .

Ideas are also extended and supported by the use of reasons and some examples or further clarification. No ideas are left unclear or unexplained.

There is also some good topic related vocabulary in the animal testing essay such as 'life saving drugs ' and 'bred ' and a mix of complex sentences , such as adverbial clauses :

'Although it may improve the lives of humans, it is not fair that animals should suffer in order to achieve this'.

Noun clauses :

'...they feel that many tests are not really important'.

And relative clauses :

'...the animals which are used are not usually wild... '

Transitions are also used effectively to ensure there is good coherence and cohesion . For example, ' On the other hand.. ' indicates a change to discuss the contrasting ideas, and ' Therefore... " and ' As a consequence..' are used to give results.

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