Animal testing is one of the most important steps in getting a drug approved by the U.S. Food and Drug Administration (FDA), and it is part of a larger process designed to protect public health. Although many FDA-approved drugs cause side effects, the FDA’s role is to determine whether the benefits of a drug outweigh its risks. As science continues to advance, new technologies have begun to change certain aspects of biomedical research, leading many to question whether animal testing is still necessary. Even so, animal testing has played a major role in scientific progress by providing biological models that share similarities with humans, allowing researchers to perform invasive procedures, making it easier to control experimental variables, and using organisms with shorter life spans and faster reproduction to speed up results. However, there are also significant drawbacks, including the fact that results do not always translate perfectly to humans, ongoing ethical concerns about animal welfare, the oversimplification of complex human diseases, and the high cost and resources required to conduct animal research.
During the animal testing process, animals are used as models that allow researchers to investigate specific aspects of biological processes. These models are selected based on how closely their biology resembles the relevant human systems being investigated. A model’s ability to mimic disease conditions as they occur in humans allows researchers to study virulence, disease progression, and potential drug treatments in ways that would be considered unethical in human subjects. Another reason animal testing has been heavily relied on is due to the degree of control researchers have over the experimental variables. Controlling constants is essential in experimental design because it helps identify the true cause of results. Animal studies allow for far greater control than studies conducted on humans. For example, Rodriguez et al. (2020) developed a high-fat diet for Iberian pigs to investigate obesity-induced chronic kidney disease. By strictly controlling the pigs’ diet, the researchers were able to induce the disease, and the findings closely resembled patterns observed in humans. In contrast, it is far more difficult to control human diets and environments, as participants are prone to making independent lifestyle choices. Researchers also would not perform this experiment on humans because it would require them to intentionally harm them, which will be discussed later. Additionally, many model organisms are selected for their rapid reproduction and short lifespans, which allow researchers to study disease progression and genetic inheritance more efficiently by compressing biological processes that would take years in humans into much shorter time frames.
Despite these advantages, animal testing presents numerous notable limitations. The first is that the direct transition from animals to humans is not guaranteed. Many drugs that progress to human trials ultimately fail, often because the physiological, anatomical, or psychological differences between animals and humans prevent accurate prediction of human outcomes. Another major limitation concerns the ethical implications of animal experimentation. Many procedures are invasive, likely causing pain and distress, which raises questions about the morality of subjecting animals to suffering for human benefit. Nonetheless, it should be noted that “pain or distress of the animals during experiments has to be minimized, i.e., refinement” (Mukherjee et al. 2022). Additionally, numerous animal models oversimplify complex human diseases and fail to capture critical factors influencing disease progression. For example, replicating mental, emotional, or cognitive disorders in animals is challenging because they typically lack the relevant biomarkers (Monteggia et al. 2018). Finally, animal research is resource-intensive, requiring specialized facilities and trained personnel, which contributes to substantial financial costs.
The impact of animal testing on medical and scientific progress is undeniable. An area of study facilitating invasive studies, allowing for a high degree of experimental control, and taking advantage of animals’ short lifespans and rapid reproduction, while limitations highlight the need for alternative approaches because of the ethical and financial burdens that accompany this method of study. Researchers are beginning to explore methods such as human organoids, organ-on-a-chip systems, and computational modeling to reduce reliance on animal testing. All these alternative ways will ensure continuous advancement in science, while the welfare of both human and animal subjects remains intact.
References
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Monteggia L. M., Heimer H., & Nestler E. J. (2018). Meeting Report: Can We Make Animal Models of Human Mental Illness?. Biological Psychiatry, 84(7), 542-545. 10.1016/j.biopsych.2018.02.010
Mukherjee P., Roy S., Ghosh D., & Nandi S. K. (2022). Role of animal models in biomedical research: a review. Laboratory Animal Research, 38(1), 18. 10.1186/s42826-022-00128-1
PhD D. (2025, July 16). FDA Announces Plan to Phase Out Animal Testing. Will That Work?. The Scientist, https://www.the-scientist.com/fda-announces-plan-to-phase-out-animal-testing-will-that-work-73173
Rodríguez R. R., González-Bulnes A., Garcia-Contreras C., Elena Rodriguez-Rodriguez A., Astiz S., Vazquez-Gomez M., Luis Pesantez J., Isabel B., Salido-Ruiz E., González J., Donate Correa J., Luis-Lima S., & Porrini E. (2019). The Iberian pig fed with high-fat diet: a model of renal disease in obesity and metabolic syndrome. International Journal of Obesity, 44(2), 457-465. 10.1038/s41366-019-0434-9