When Are Alternatives to Animals Used in Research?

While many different strategies, models, methods, and technologies are used in biomedical research, the specificity of the individual research question dictates what approaches are appropriate. In other words, different research questions necessitate the use of different approaches. Some approaches involve animal models, some do not. While animal models are critical and employed in all fields of biomedical research, NIH encourages researchers to use complementary approaches to ensure rigorous and reproducible studies whenever possible.

NIH is committed to continuing to develop non-animal model alternative methods. We also support efforts to replace, reduce, and refine (also referred to as the “3Rs”) the use of animal models in our supported studies. Some examples include:

• Testing cells and tissues in test tubes or cell cultures
• 3D tissue culture, also referred to as organs-on-a-chip
• Computational and mathematical models
• Stem cell research
• Non-invasive diagnostic imaging
• Clinical research involving people

Image from https://ncats.nih.gov

NIH also provides training and other resources for scientists to assist them in identifying and/or developing non-animal alternative approaches. Some of these resources are focused on the 3Rs. The resources below are helpful to learn more about alternatives to animal models, including the 3Rs:

• A yearly, NIH co-sponsored symposium with presentations from international experts on the latest advances in the 3Rs, effective use of animal models, scientific rigor and animal welfare. Click here to see recordings from the 2020 and 2021 events.
• NIH leads the Interagency Coordinating Committee  on the Validation of Alternative Methods, which coordinates activities within the federal government relevant to new toxicology test method evaluation, acceptance, and use (read more here ).
• Nine U.S. Government Principles , adopted in 1985, are the foundation for humane care and use of animals in biomedical research in this country. Of particular interest is the third principle that requires the minimum number of animals be used as scientifically necessary and replace non-animal models wherever possible. Principle IV requires researchers to avoid or minimize discomfort, distress, and pain in animals consistent with sound scientific practices and meets the 3Rs requirement as well.

Though these alternative approaches exist, and advances are being made every day, research with animals continues to be essential for understanding human diseases, biological processes, and developing treatments. We are not at a point where alternative approaches can completely replace the use of animals at this time. The alternatives simply cannot accurately replicate or model all the biologic and behavioral aspects of human disease. Until that time, animal models will remain integral for NIH-supported research. However, NIH and NIH funded scientists are continually working to reduce animal use and improve the welfare for animals that are essential for scientific progress.