Animal testing is carried out worldwide. Every year millions of vertebrate animals are used for research and experimentation. The practice is regulated to varying degrees in different countries. Opinions about the necessity, acceptability, and justification of animal testing vary widely. The British Royal Society, which supports animal experimentation, has argued that virtually all medical achievements in the 20th century have had to rely on the use of animals in some way. Growing public opposition to the practice has, however, forced some governments to give statements on the practice. Those in opposition to animal testing primarily base their arguments on ethics, morality, and the unreliable nature of using animals as test subjects.
Use Of Animals In Experiments
About 31.1% of animals in science are used in basic research, while 11.9% are used for translational and applied research, which includes projects that test primary research findings for medical application. Both basic research and translational and applied research are interconnected. Both of them make up 43% of the total expenditure for medical research. Animal experimentation is done to clarify previously unknown life processes and fundamental biological relationships. The findings are then used to improve diagnostics and treatment of human diseases and illnesses. Approximately 28.2% of animals used for research do not get exposed to experimental treatment while alive and have to be put down to gain tissue and cells. The samples are then used to study biochemical processes and to test new pharmacological treatment methods. About 23.7% of animals are used for safety checks, toxicology tests, and quality tests to ensure safety for drugs that come into contact with humans. Animals used in research are mainly small mammals such as guinea pigs, mice, rats, and rabbits.
Birds and fish are also used for specific experiments. Mice make up 68% of animals used for testing, while rats make up 13% of the total number of animals used for testing. Both mice and rats are also the most commonly used for organ extraction. The mouse genome was decoded a few years ago and is relatively simple to manipulate from a technical standpoint, which makes mice the essential test subjects as they offer researchers insight into the genetic foundations of life processes and diseases. Tests and experiments on fish have also increased significantly over the years (currently at 9.8%) since the Zebra-fish genome was decoded. Other species are used to some extent.
Arguments Against A Ban On Animal Testing
The findings from animal testing are not only used in advancing human medicine but are also used in the development of diagnostic and therapeutic procedures in veterinary medicine. Humans and animals also share several diseases, including congenital deformities and arteriosclerosis in rabbits, visual system diseases in cats, and specific forms of blood disorders, cancer, diabetes, and ulcers. Dogs, for example, have a naturally occurring blood clotting disorder that leads to life-threatening internal bleeding. The disorder can be treated for hemophilia based on gene therapy developed for humans. The transfer of treatment methods is relatively easy since methods practiced in human medicine were developed through animal testing. The development of veterinary medicine also utilizes animal testing as an indispensable method in developing animal medicine. Typically, the studies are designed such that potential patient or target species is the subject of investigation. Vaccination strategies for fatal diseases like bovine tuberculosis, leucosis, and distemper were all developed through animal experimentation. Such medicine and other forms of veterinary medicine help treat livestock and are also used in nature preservation projects to protect endangered species.
Body cells and biochemical processes necessary for life are quite similar across different species of animals. Molecular genetics can prove that all organisms on earth have the same origin. Animals share genes responsible for body structures that later modified in the course of evolution. Such similarities even allow comparisons of genes and metabolic processes between humans and bacteria. Human bodies are, however, much more complex hence the need for higher animals. Animal experiments allow researchers to predict desired outcomes and 70% of adverse effects on humans. For example, acetylsalicylic acid, the active component of analgesic Aspirin, alleviates pain in both humans and rats but can also result in increased bleeding in both species. Asbestos causes lung cancer in both humans and rats.
Similarly, plastic solvents also cause liver cancer in both humans and rats. In such experiments, one can conclude the efficacy and safety tests on animals can significantly minimize the risk of new treatment methods on humans. During preclinical animal studies, 36% of substances tested do not proceed to subsequent clinical trials on humans due to safety risks and undesirable side effects observed in animals. Animal testing, therefore, helps prevent the administration of substances that are potentially life-threatening or harmful to humans. The principle of transferability also works in reverse.
Arguments In Favor Of Ban
The lack of sufficient congruence between human diseases and animal models presents significant obstacles to translational reliability. When diseases that affect humans are artificially induced into animals, the challenges of reproducing the complexity of human diseases in animal models limit the usefulness of data obtained. In cases where animal experiments are standardized, the translation of results may also fail due to differences between the human condition and the experimental animal model. For example, stroke is well understood, yet modeling the disease accurately in animals has proven to be an exercise in futility. About 90% of drugs that show promising results during animal testing fail during human trials. Some of the drugs with the lowest success rates include cancer drugs (with a 5% approval rate after going through clinical trials), psychiatry drugs (with a 6% success rate), and heart drugs (with a 7% success rate).
Harm Due To Results From Misleading Animal Experiments
The use of non-predictive animal experiments can lead to human suffering by producing misleading efficacy and safety data. Misleading data from animal tests can result in clinical trials of harmful or faulty substances, therefore exposing humans to unnecessary risks. Toxicity studies on animals are poor predictors of the toxic effects of drugs on humans. Humans have, in the past, been significantly harmed because researchers were misled by the efficacy and safety profile of a new drug based on animal testing. Volunteers in clinical trials are, therefore, given hope and a false sense of security due to misguided safety and efficacy experiments on animals. Misleading results from animal tests can also point researches in the wrong direction leading to wastage of time and significant investment.
Animal tests also result in human suffering in the form of the opportunity cost of abandoning promising drugs based on misleading animal testing results. As candidate drugs go through development and human testing based on animal tests, some drugs are sometimes abandoned due to unsuccessful results during animal testing. It is difficult to determine the number of missed opportunities as a result of misleading results from animal tests since the pharmaceutical company’s preclinical data is proprietary hence publicly unavailable. However, only 5 in every 500 to 1,000 potential drugs proceed to clinical trials. Potential drugs may be abandoned due to tests that do not apply to humans.
An editorial published in Nature Review Drug Discovery described instances involving drugs whose animal testing results could have derailed their development. It explains how tamoxifen, an effective drug for certain types of breast cancer, would have been abandoned if its ability to cause liver tumors in rats was discovered during testing as opposed to after being released to the market. Gleevec, which is used to treat chronic myelogenous leukemia, would also have been abandoned as it showed adverse effects in five species tested, including dogs, which experienced severe liver damage when exposed to the drug. Liver toxicity was, however, not detected in human trials. Fortunately for patients suffering from both ailments, the drugs made it to the market.
There Are Alternative Methods
Scientists have developed methods of testing products and studying diseases that replace the cruel use of animals. The techniques are also relevant to human health. Some of the alternative methods include in vitro testing and in-silico modeling. The methods require less manpower for maintenance, are less time consuming, and less costly. The methods are also not hindered by challenges related to species differences present in animal testing. In vitro testing involves the use of artificially grown cells or tissue in controlled conditions to study drugs and chemical effects. The experimental tissue is typically preserved in a suitable medium for days to years. Today the method is used to test cosmetics and medicines with a high degree of efficacy. Organ-on-chip technology has also been developed. The devices contain human cells grown in modern systems that mimic human organ functions. Computer modeling, which is also known as in silico modeling involves the use of sophisticated computer models that simulate the progression of diseases and human biology. Studies have shown that computer models can accurately predict ways in which new drugs can react in the human body.
The Three Rs principle
The use of animals for experiments is a controversial issue that is acknowledged by the scientific community. When animal experimentation is entirely unavoidable, there is a consensus that the testing should be restricted to a necessary minimum. Russel and Burch introduced the three Rs principle in 1959 as a guide for animal experimentation. The aim was to avoid animal testing where possible, limit harm caused to animals during testing, and to minimize their number. The three Rs are Replacement, Reduction, and Refinement. Replacement refers to the preferred use of non-animal methods whenever possible. Reduction refers to the use of a minimal number of animals to obtain maximum data or information. Refinement refers to the improvement of scientific techniques to minimize the pain and suffering of animals used for experiments over their lifetime.