ArticleNovember 20, 2022

Championing the 3 Rs

The “3 Rs alternatives” refers to the refinementreduction, and replacement, of animals used in research, teaching, testing, and exhibition. Drs. William Russell and Rex Burch first described the 3 Rs in their 1959 book, The Principles of Humane Experimental Technique. Russell and Burch advocated for new scientific approaches that would minimize the pain and distress of research animals while maintaining scientific integrity. Let’s take a look at how each of the 3 Rs are defined:


Refinement refers to modifications of husbandry, veterinary practices, or experimental procedures that minimize or eliminate animals’ pain and distress and improve their welfare. A few examples of refinement are anesthetics and analgesics, improved housing designs (Fig 1), environmental enrichments (Fig 2), and humane animal handling (Fig 3).

Feta out on her morning walk.
Feta out on her morning walk.
Non-human primate enclosure
Non-human primate enclosure furnished with varied environmental enrichment and bedded with straw foraging substrate to maximize cognitive stimulation throughout the day.
Neuralink trainer guides Blue Belle and Coraline outdoors using a target pole
Neuralink trainer guides Blue Belle and Coraline outdoors using a target pole. Each snout touch to the target is reinforced with a preferred food item. Rather than using a fear based strategy to shift animals, target pole training allows animals to make choices for themselves.


Reduction refers to 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.


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 Replacement omits the use of animals completely. Some examples include training manikins, human tissues and cells, computer models, and microphysiological systems or proxies (Fig 4).
  • Partial/Relative Replacement still requires the use of animals, 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).

The global animal medical research community has adopted the 3 Rs blueprint for how companies, universities, and other organizations should strive to treat animals in their care while contributing to important medical advancements.

We challenge ourselves every day to improve the experience of our animals, reduce the numbers of animals required, and explore alternatives to animal use. We take this effort seriously and want to transparently share how we have tackled some of these tough issues.

In the coming months, our animal care blog will release a multi-part series highlighting the refinements, reduction efforts, and replacements we focused on in the past year. We will continue to update the blog throughout the coming year. Check out our line-up of topics to come:

Lab-grown motor neuronal organoids in blue, pink, yellow, and black
Lab-grown motor neuronal organoids

Refinement Series

  • Husbandry
    • Animal Well-Being Assessments
    • Housing and Diet
    • Communication Buttons
  • Environmental Enrichment
    • Behavioral Engineering - Hal Markowitz
    • S.P.I.D.E.R. Framework
    • Standard Care vs. Enrichment
  • Animal Behavior and Training
    • Motivation Strategies
    • Behavior Data Collection
    • Behavioral Analysis
  • Veterinary Medicine
    • Building Trust Banks
    • Cooperative Care
    • Analgesic and Anesthetic Advancements
  • Social Housing
    • Match Making
    • Social Structures
    • Evolving Relationships
  • Medical Research
    • Advancing Technology
    • Maximizing Agency during Data Collection
    • Expert Staffing

Reduction Series

  • The Role of the Institutional Animal Care and Use Committee (IACUC)
  • Statistical Power and Study Design

Replacement Series

  • Benchtop Proxies
  • Advancing Technology

If you are an animal welfare scientist or have expertise in behavioral analysis, love working with animals, and want to revolutionize animal welfare, please check out our jobs page!