The 3Rs (replacement, reduction, and refinement) serve as a framework for responsibly using animals in research, teaching, testing, and exhibition. First defined by Drs. William Russell and Rex Burch in 1959, the 3Rs emphasize minimizing animal pain and distress while advancing high-quality science.
This webpage provides definitions, funding opportunities, relevant 3Rs methods, recorded presentations, and other resources to help scientists, veterinarians, institutional animal care and use committee (IACUC) members, and animal care staff integrate animal use alternatives into daily practice.
Defining the 3Rs
- Replacement refers to technologies or approaches that directly replace or avoid the use of animals. Replacement can be broken down into two categories: Full/Absolute and Partial/Relative.
- Full/Absolute Replacement avoids the use of animals completely. Some examples include training manikins, human tissues and cells, computer models, and microphysiological systems.
- Partial/Relative Replacement still requires animal use, but the animals do not experience pain or distress during the study. Some examples include animal-derived tissue/organs for in vitro studies, zebrafish embryos, and transcutaneous electrical resistance test (TER).
- Reduction involves methods that help obtain comparable levels of information from the use of fewer animals. Scientists can reduce the number of animals used in research through strategies such as appropriate experimental design, correct statistical evaluation, and sharing resources/animals.
- Refinement refers to modifications of husbandry or experimental procedures that minimize or eliminate animals’ pain and distress and improve their welfare. A few examples of refinement are anesthetics and analgesics, humane animal handling, environmental enrichments, and humane endpoints.
Definitions from ‘The Principles of Humane Experimental Technique’ (1959) and the ‘Guide for the Care and Use of Laboratory Animals’ (2011).
Featured 3Rs Topics
The library's Animal Welfare Information Center provides information regarding pain recognition, anesthesia and analgesia, humane endpoints, and euthanasia of laboratory animals.
The library's Animal Welfare Information Center shares resources and guidelines for addressing the 3Rs in wildlife research and conducting various procedures and techniques while considering animal welfare.
Finding 3Rs Literature and Resources
Alternatives Literature Searching
The National Agricultural Library's Animal Welfare Information Center provides a step-by-step guide to literature searching for alternatives, examples of literature searches, best databases for 3Rs alternatives literature, and more.
Other 3Rs Resources
3Rs organizations from around the world offer tutorials, presentations, pictures, and other materials sharing various 3Rs methods and technologies. The websites below provide reliable starting points for identifying animal use alternatives relevant to your work.
Mention of commercial enterprises or brand names does not constitute endorsement or imply preference by the U.S. Department of Agriculture.
Other Websites with 3Rs Resources
Animal Welfare Institute (AWI)
AWI hosts the Refinement Database with over 8,000 scientific articles, books, and other publications related to improving animal welfare and minimizing the pain and distress of animals used in research and testing.
European Union Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM)
EURL ECVAM focuses on developing, validating, and promoting non‑animal testing methods and providing educational resources, including training tools and guidance materials, to advance alternatives to animal use.
International Network for Humane Education (InterNICHE)
InterNICHE provides materials such as videos, databases, and books that focus on animal use and alternatives for training and education within biological science as well as human and veterinary medicine.
Johns Hopkins Center for Alternatives to Animal Testing (CAAT)
CAAT offers 3Rs tools, training, and materials for toxicology, microphysiological systems, exposomics, and other research areas.
National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs)
NC3Rs shares a variety of resources such as videos, posters, and scientific publications on 3Rs methods and technologies for different animal species and non-animal methods used in research.
NICEATM shares guidance, scientific publications, webinars, and other resources about methods used to replace, reduce, or refine animal use during chemical safety testing.
Norecopa maintains approximately 11,000 webpages that contain articles, videos, presentations, reports, photos, and more on 3Rs alternatives methods and technologies.
Replacing Animal Research provides tools, training, and guides on non‑animal research methods, including funding support, experimental design, publishing guidance, and teaching materials, to help researchers, educators, and institutions replace animal use in science.
Standing Committee on Animal Health, Conservation, and Research
As part of the National Academies' Board on Animal Health Sciences, Conversation, and Research, the Committee publishes workshop proceedings on animal research, animal welfare, and 3Rs topics.
Science for Animal Welfare offers a variety of written publications, including its Animal Welfare scientific journal that's open access, a collaborative book series with Wiley Blackwell on animal welfare, practical handbooks and guides on animal care and welfare, and collections of papers from its symposia and workshops.
3RsC develops resource hubs with training materials and guides for replacement, reduction, and species-specific refinement methods, such as rodent health monitoring, microphysiological systems, and compassion fatigue.
3Rs Principles in Wildlife Research
This website provides guidance on applying the 3Rs to wildlife studies by offering information on responsible animal use, examples of peer‑reviewed non‑lethal and non‑invasive methods, instructional videos, and a decision‑support tool to help scientists choose approaches that minimize impacts on animal welfare.
Annual 3Rs Symposium
The Annual 3Rs Symposium brings together investigators, veterinarians, animal care staff, Institutional Animal Care and Use Committee (IACUC) members, and others involved in animal research to discuss 3Rs methods and techniques for a wide range of animals used in research. The 2013 through 2019 symposiums focused on social housing of laboratory animals, whereas symposiums after 2019 focused more generally on 3Rs topics. The symposium is jointly hosted by USDA's, NAL, Animal Welfare Information Center (AWIC); NIH's Office of Laboratory Animal Welfare (OLAW); the Johns Hopkins Department of Molecular and Comparative Pathobiology; and the Johns Hopkins Center for Alternatives to Animal Testing (CAAT).
View past Annual 3Rs Symposiums for free
Find discussions on microphysiological systems, animal/organ sharing, optimizing breeding, research design and statistical strategies among other topics.
View presentations on liver-chip technologies, environmental health monitoring, refinement and enrichment strategies, regulatory insights into the 3Rs among other topics
Watch presentations on mixed strain housing, best animal models for disease research, adoption programs, collaborating to solve animal welfare issues and other topics
Find talks on 3Rs in machine learning and literature searching, animal models in COVID research, microphysiological systems, assessing animal welfare and other topics
View presentations on minibrain organoids, grimace scales, PRIMatE data exchange, using pets in research, rodent and pig handling, and PREPARE guidelines among other topics
Find discussions on zoo animals, rabbits, mice, and rats
Watch presentations on fish, rats, mice rabbits, and miniature swine
View talks on rabbits and miniature swine
Watch discussions on nonhuman primates, zebrafish, and amphibians
Find talks on ruminants, nonhuman primates, rabbits, guinea pigs, and hamsters
View presentations on rabbits, pigs, and nonhuman primates
3Rs Funding Opportunities
- The Johns Hopkins Center for Alternatives to Animal Testing (CAAT) offers the Reduction Grant for research projects aimed at reducing animal use through synthesis and analysis of existing published research, such as systematic reviews, scoping reviews, or meta-analyses.
- Deadline: September 15, 2026
- The Johns Hopkins Center for Alternatives to Animal Testing (CCAT) funds the Humane Education Grant, which supports the development of animal-free teaching and training resources in veterinary, medical, and New Approach Methodologies (NAMs) education.
- Deadline: September 15, 2026
- The Society of Toxicology (SOT) supports the Colgate-Palmolive Grant for Alternative Research to fund projects that promote, develop, refine, or validate acceptable animal replacement methods to facilitate the safety assessment of new chemicals and formulations. SOT membership is not required to apply.
- Deadline: October 9, 2026
- The American College of Laboratory Animal Science (ACLAM) Foundation funds research in areas of laboratory animal science and medicine, such as analgesia/anesthesia, behavior/well-being, husbandry, and refinements of animal models. A letter of intent is due prior to the invitation to submit a full grant proposal.
- Deadline: December 4, 2026
- Science for Animal Welfare offers Small Research Grants (up to £5,000) and Large Research Grants (over £5,00) for research and other activities focused on understanding or improving animal welfare.
- Deadline: Rolling deadline
Additional Resources
Measuring U.S. Federal Agency Progress Toward Implementation of Alternative Methods in Toxicity Testing
The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) Metrics Workgroup gives their recommendations along with references and other materials that can be used to follow federal agency progress in promoting the use of alternative toxicological methods.
The Principles of Humane Experimental Technique
Drs. Russell and Burch were the creators of the 3Rs concept in animal research. The concept was published in their 1959 book, "The Principles of Humane Experimental Technique".
PREPARE Guidelines
PREPARE (Planning Research and Experimental Procedures on Animals: Recommendations for Excellence) is a set of guidelines to help researchers with planning experiments involving animals. Considering 3Rs alternatives is part of the planning.
New Approach Methodologies (NAMs) in Ecotoxicology
This bibliography provides peer-reviewed literature published between 2010 and 2025 on non-animal technologies and approaches used for chemical hazard, exposure and risk assessment testing.