Animal researchhas had a crucial role in many of the scientific and medical advances of thepast century and continues to support our understanding of various diseases.Worldwide, people and animals benefit because of these medical advances, andthe subsequent development of new medicines and treatments. Without animalresearch, much of this advancement would likely have been impossible (Festing andWilkinson 2007).In clinicaltesting laboratories, experimental animals are removed from their groups andused as a tool regardless of their natural instincts and either the wholeanimal or its organs and tissues are used for the experimental procedures. Forthis purpose animals are euthanized or if the animals survive the clinicaltesting they are euthanised at the end of the experiment (Rusche, 2003). The issue of the pain,distress and death the animals experience in scientific experimentation hasbeen a debating issue for a long time (Doke and Dhawale, 2015), whichcontinues to generate public and political concern worldwide (Taylor et al.
,2008).The advancementof research and development in medical technology has led to an upsurge in thenumber of animals used in research. The percentage of articles reporting theuse of animals has increased in the past 15 years.
With the rising popularityof genetic modification methods, it is reported that genetically-modifiedanimal use has more than doubled since 1997 (Ormandy et al., 2009). Severalestimates of global laboratory animal use have been published. Unfortunately,the accuracy of animal use estimates has been significantly impeded by considerablevariation in reporting standards internationally (Knight, 2011). Many countriesonly record or publish live animal use, and exclude the substantial number of animalskilled prior to procedures for purposes such as the harvesting of organs orother tissues. Some countries do not record or publish animal use statistics atall. This is why the comprehensive figure of 115.3 million animals usedworldwide yearly for research calculated by Taylor et al.
(2008) may still be an underestimate. The considerablenumber of animals that are being used yearly is one of the reasons possible alternativesneed to be investigated. Animal experimentationis generally accepted in society on the basis that progress in medical andbiological research relies on the use of experimental animals (Festing et al., 2002) and because of the claimedbenefits animal experimentation provides for human beings. Based on thepresumption that laboratory animal models reasonably reflect human outcomes andreactions, animal research is widespread in its use in the safety and efficacytesting of drugs and other clinical interventions.
Animals arealso used in education, particularly for medical and veterinarian education.Veterinarians may have the largest justification for using animals, as trainee veterinariansmust be able to provide treatment for real animal patients once qualified andrecognise the clinical signs of diseases, as well as perform a variety ofsurgeries and procedures including euthanasia for injured or terminally illpatients (Knight, 2011).Despite the numerousadvantages animal research has provided and continues to provide, the call for non-animalalternatives is ever-increasing. Certain groups of people take an extreme viewthat we have no right to make use of animals for our advantage, for food,clothing, pleasure, research, or anything else (Smyth, 1978). From aphilosophical perspective one may question why humans have made the assumptionthat we are free to use animals however we wish. Could the simple answer be becauseof utilitarian reasons: we believe that the cost of the animal lives is worthit for the benefit of humans? The generalconsensus among the public, including many of those who have no objections tousing animals in other ways such as for food or clothing, is that it is wrongto cause pain to animals. It is generally accepted that the assumption of theright to use animals goes with the responsibility not to cause unnecessary painor distress.
A significant motivation in the search for alternatives to animalexperimentation is ultimately to avoid causing pain to animals. If experiments couldpossibly involve inflicting pain on animals then, ethically, there is not onlya need to consider alternatives, but if these are not feasible, to ask whetherthe resulting information is worth the pain caused (Smyth, 1978). In the EuropeanUnion it is a legal requirement that a scientist planning a research projectthat could involve vertebrates (and some other species such as Octopus vulgaris) must consider whetherits objectives could be achieved using alternative methods. Although this legalrequirement may not exist in other countries, it is ethically and economicallydesirable to consider other alternatives (Festing et al.
, 2002).As a result ofthe animals that are used for medical and veterinary education, adverse impactsmay be experienced by students. The use and disposal of healthy animals maycause powerful emotional experiences and high degree of stress which have greatpotential to affect the students’ learning adversely, and indeed their ownhealth (Knight, 2011).
The expense ofresearch involving animals can be a negative aspect, especially if claims thatanimals are not as useful are true. Apart from the cost of the animals ifbought, the cost feeding and maintaining the animals themselves can mount. Ifalternatives to animals in research could possibly be cheaper, this may be asolution to economic issues of animal experimentation and should beinvestigated (Smyth, 1978). Animalsfrequently fail to accurately mirror human responses with sufficient accuracy.
Variancesbetween different species may exist in absorption, distribution, metabolism,and elimination pathways or rates, resulting in differing toxico- orpharmacokinetics. Differences may also occur in toxico- or pharmacodynamics,and all of these factors may contribute to differences in the organ systemsaffected, and in the nature and magnitude of those effects. Given this, theremay be a need for researching into alternatives that will give more accurate resultsto correspond with a human response.In addition,stresses that can be experienced by the laboratory animals when they are beinghandled and during routine laboratory procedures, especially the stressfulmethods of dose administration during toxicity tests can have an effect on theoutcome. Such stresses have the potential to alter their physiological,hormonal, and immune status in ways that may alter the progression of diseasesand distort responses to chemicals and test pharmaceuticals, thus rendering anyresults of the experiment less accurate (Knight, 2011). With allexperiments, whether it is required by law or not, it is ethically desirablefor some sort of cost/benefit analysis to be considered, where the cost is thepain, suffering and distress or death inflicted upon the animals, and thebenefit is the probability that the project will be successful and providepotential benefits to humans or animals (Festing et al.
, 2002). The Three Rs(Reduction, Replacement and Refinement) were first proposed by Russel and Burch(1959). They have become widely accepted principles in the governance of humaneanimal research (Ormandy et al., 2009). Theseprinciples encourage researchers to consider reducing the number of animalsused in experiments to a minimum that is necessary, refine the experiment tolimit the pain and distress to which animals are exposed, and replace the useof animals with non-animal alternatives wherever possible (Ferdowsian and Beck,2011).
Activistsagainst the use of animals in experiments are increasingly gaining support ofthe wider public, putting significant pressure on government officials to putharsher restrictions on animal experimentation (Bennett and Ringach, 2016). Variousalternatives to the use of animals in research have been suggested which canavoid the use of animals in such research (Balls, 2002). Thesemethods can provide a substitute for drug and chemical testing up to an extent(Doke and Dhawale, 2015). Duringthe past two decades the development and availability of non-harmful teachingmethods has risen significantly. These include computer simulations, highquality videos, ethically sourced cadavers (acquired from animals that havebeen euthanised for medical reasons), models, and surgical simulators. Ideally,humane veterinary surgicalcourses that make use of non-animal alternatives when possible are comprised ofseveral stages. Students could begin by learning basic manual skills, such as suturingand instrument handling, then progress to using knot-tying boards, plasticorgans, and similar models (Knight, 2011).
No pain will be involved by avoiding the dissection of animals, and models willreduce the number of animals used (Smyth, 1978). They may then move on to practicesurgery performed on ethically sourced cadavers. Finally, students will watch,assist with, and then perform under close supervision surgery on real patientsthat benefit from the surgery rather than healthy animals that would be later euthanized(Knight, 2011). In vitro cell and tissue cultures is animportant alternative for animal experiments. It involves the isolation ofcells or tissues taken from an organ (liver, kidney, brain, skin, etc.) of ananimal and kept outside of the body in a suitable growth medium for an extendedperiod. They provide an opportunity to study the cellular response in a closedsystem, where the experimental conditions can be preserved. These models canprovide preliminary information for the results of in vivo experiments (Doke and Dhawale, 2015).
Although this doesnot eliminate animals entirely from the equation, it reduces the total numberof animals used. In vitro cell and tissue cultures are often used forinitial screenings of molecules or chemicals of drugs to review their toxicityand efficacy (Steinhoff et al., 2000). In fact, the toxicity andefficacy of almost all cosmetics, drugs and chemicals are tested for usingthese kinds of experiments (Doke and Dhawale, 2015). If humans or human tissuesare used in vitro, this can have many advantages as this alternative maygenerate faster, cheaper results that are more reliably predictive for humanoutcomes, and may deliver greater insights into human biochemical processes (Knight,2011).
Computers can beutilised to assist scientists in understanding the various basic principles ofbiology and may have the potential to replace animals in the future. Computergenerated simulations are able to predict the different biological and toxiceffects a chemical or potential drug candidate can have and from these primaryscreenings, promising molecules go on to be used for in vivo experimentation(Doke and Dhawale, 2015). All of the majorpharmaceutical and biotechnology companies in the world make use of computationaldesign tools. A noteworthysoftware known as Computer Aided Drug Design (CADD) is a practical assistanceto drug designers and is a significant guide to drug synthesis(Richards, 1994). CADD can be used to identify likely receptor binding sites ofa drug molecule, which avoids in vivo testingof chemicals that have no biological activity (Vedani, 1991). Consequently,the total number of animals used in preliminary drug testing experimentsdecreases, achieving the objectives of the three Rs (Doke and Dhawale, 2015).In comparison to conducting experiments using animals to identify receptorbinding sites, such computerised systems are rapid and inexpensive (Knight,2011) and therefore desirable due to their economic benefits over animalexperimentation.
While these computergenerated simulations can give researchers ideas of possibilities of drugdesign and predictions of the properties of these new drugs, it cannot test outthe subsequent drug produced. Practically, this must be done on animals, meaningthat this is not truly an alternative to animals. They also enable theresearchers to make more use of the data they get from animal experiments, andit may facilitate the researchers to design better experiments which will leadto better quality results ultimately reducing total animals used inexperimentation in the future (Smyth, 1978).
Microdosing is a relatively newmethod of obtaining human metabolism data through which humanparticipants are administered a small dose of a test compound which allows researchers to studythe pharmacological effects without harming the participants. Microdosing allows safer human studies as well asreducing the use of animals in preclinical toxicology. It will also permitsmarter candidate selection by taking investigational drugs into humans earlier(Lappin and Garner, 2003). Replacementcould also mean replacing ‘higher’ animals with ‘lower’ animals.
Eggs, plants,reptiles, amphibians, microorganisms and invertebrates are all examples thathave been used to replace warm-blooded animals in studies (Ranganatha andKuppast, 2012). However, the majority of animals used in laboratories arehigher vertebrates, such as mammals and birds. These higher animals are knownto possess the psychological and neuro-anatomical capacities necessary to feelpain, fear, and distress, making it ethically undesirable to use them forexperimentation (Knight, 2011).In manycountries animal use legislations often only regulate the use of livevertebrates, so the use of minimally sentient animals from lower phylogeneticorders or early developmental vertebral stages in experimentation is anattractive option as its increases compliance to such legislations (Knight,2011).Lowervertebrates are frequently used since they are closely genetically related tohigher vertebrates including mammals (Doke and Dhawale, 2015).
An example of which iszebra fish, which make ideal model organisms for the study ofvertebrate development. This is due to a quick generation time, and a couple are able toproduce up to 200 embryos every 7 days. Furthermore, the embryos and larvae aresmall and robust, go through rapid external development and are transparent (Tavaresand Lopes, 2013). Invertebrateorganisms have been used as models for research and teaching for hundreds ofyears. However, invertebrates do not have an adaptive immune system and have anundeveloped organ system which limits their use as models in human diseases. However,they hold many advantages, such as their simple anatomy and small size, as wellas a short life cycle so that a large sample of invertebrates can be studied ina single experiment within a short period, creating less ethical implications.The cost of housing them is dramatically cheaper when compared to animals.
Forexample, thousands of flies could be kept in an enclosure where only few micecan be kept (Wilson-Sanders, 2011).Drosophilaisone of the most expansively studied invertebrates in research (Gilbert,2008). Its complete genome has been sequenced which allows researchers tobetter study molecular mechanisms that cause human diseases. Drosophila require an exceptionallylow cost of care, breeding and screening when compared to mammals. Results fromDrosophila models are quickly generated due a brief life cycle. Anotherexample of a widely used invertebrate is C. elegans which, like Drosophila,has a very short life cycle (2-3 weeks), and is cheap to house, manage andbreed (Doke and Dhawale, 2015).
Many experimentsare poorly designed and use statistics that are too basic, often limiting thestatistical validity of the conclusions from the study (Knight, 2011). Becauseof this, experiments may have to be repeated, and animals would have been usedfor nothing. It is therefore very important ensure a well-designed experiment asany responsible scientist will want to avoid the wasting of an animal’s life. Excessivelylarge experiments are not only unethical, but are also a waste of scientificresources. Researchers would benefit from having the smallest sample size thatcan still achieve the objectives of the study. If the same number of animalscould be used in more experiments rather than just a surplus wasted in a singleexperiment, then scientific output would increase, which, in the long run, savesanimals and scientific resources (Festing et al., 2002). In order tokeep the number of animals to the minimum necessary and avoid any repetition ofexperiments, researchers must have a clear understanding of the objectives ofthe study, be able to use appropriate statistical analysis to extract all of theuseful information of the experiment, and interpret the results carefully (Festinget al.
, 2002). Solutions could also include training any researchersinvolved in experiments that include the use of animals in statistics or thedirect input of statisticians into experimental design and data analysis inorder to achieve better sample sizes (Knight, 2011). Alternatives toanimal models may be more ethically sound, but they can limit the utility ofthe scientific outcomes in a lot of research areas.
One such research area isanimal models of human genetic diseases. Animal models are vital for medicalresearch, as they are used for in-depth investigations of the physiologicalbasis of different genetic diseases and are of more use than cell culturestudies as some substances that do not produce a responsein an isolated cell will evoke a response in the whole animal (Murphy, 1991) andtherefore show a morerealistic response to drug treatments. Human volunteers would not be an option,firstly in order to test a hypothesis about a genetic disease and how it develops,a sufficient number of subjects are needed in order to statistically test theresults of an experiment. Animals for experimentation are widely available andeasy to breed with a short generation time in comparison to humans. It is much easier to obtain a large sample ofanimals to achieve significant results.
The conditions in an experiment must beclosely controlled i.e. themanipulation of one variable while keeping the others constant to observe theconsequences of that change alone. This is easily achieved using animals thatcan be kept in the lab, whereas humans may have several factors in theirlifestyle that could affect the results. On top of this,with gene targeting, gene knockouts and transgenesis, researchers are able tobe specific about the exact genetic defect they require in an animal model. Withoutsuch models that have been purpose built to possess key genetic diseases,progress will be very slow or impossible in the development of treatments forgenetic diseases. Though completereplacement of animals in experimentation is ethically desirable, it isunrealistic to expect this to be a reality in every area of scientific researchor education in the immediate future. Although many of the alternativesdiscussed in this essay can provide a means to potentially reduce the number ofanimals subjected to experiments, it isn’t currently possible for any of themto completely replace animal experiments.
The biggest issue is the difficultyof creating models that can accurately mirror the physiological systems ofwhole living organisms (Festing and Wilkinson, 2007). However, if we make theassumption that animals are at our disposal to use in research, we must also assumethat we are responsible for ensuring such animals are not unnecessarily putunder any distress, pain or fear and make their lives as comfortable aspossible. It should also be a priority to replace them if at all possible or toreduce the number needed while still being sure to achieve good data so thatthe animals are not wasted.