The Three Rs of animal ethics

The Three Rs are fundamental animal welfare principles that provide useful strategies regarding the treatment of animals for research, testing and teaching.

The following text is an excerpt from Exploring the Three Rs of Animal Ethics with Māori Ideas (a version of the text is available as a PDF in te reo Māori only or a bilingual version).

Rights: Public domain

Galen dissecting a pig

The Ancient Roman physician Galen of Pergamon believed dissection was vital for the education of surgeons and physicians. His dissections were lively public spectacles.

The use of animals to explore how the human body ‘works’ was first recorded in ancient Rome, but it was not until the Renaissance that the use of animals in scientific experimentation began to proliferate. Such use of animals was justified by the belief that the experiments would benefit humans and that animals did not feel pain.

Rights: Routledge

Principles of Humane Experimental Technique cover

Cover to Principles of Humane Experimental Technique by William Russell and Rex Burch, the 1959 book that codified many of today’s ethical approaches to animal testing.

Concerns about how animals were being used in experimentation began to grow in the first half of the 20th century. In 1954, the UK Universities Federation for Animal Welfare commissioned William Russell, assisted by Rex Burch, to research how more humane methods could be introduced into scientific research. The outcome of their work was the seminal and key text in the field The Principles of Humane Experimental Technique. This book explains ethical concerns for the welfare of animals in scientific experimentation and introduces the set of principles for research, testing and teaching known as the Three Rs, dubbed the “removal of inhumanity”. They argue that adopting humane methods leads to good data since animals are likely to be less stressed.

Replacement, reduction and refinement

The Three Rs are three principles or strategies for the use of animals in research, testing and teaching practice: replacement, reduction and refinement.

• Replacement means avoiding the use of sentient animals entirely, replacing them with insentient material.
• Reduction means reducing the number of animals being used to the minimum needed to obtain the required information.
• Refinement means decreasing the incidence or severity of the inhumane procedures being applied to animals when they still need to be used.

Rights: ANZCCART NZ

Three Rs poster

The Three Rs – replacement, reduction and refinement – are principles intended to minimise the harm and suffering of animals within laboratory settings.

Download a PDF version here.

These three principles are hierarchical in their logic. Replacement is the ideal but sometimes cannot be utilised, in which case reduction applies, whereby the number of animals to be used should be reduced as much as possible. Then the principle of refinement is applied, with the aim of minimising as much as possible the amount of stress that these animals will endure.

The Three Rs were introduced decades ago, and since then, advances in information technology, scientific techniques and understanding of animal behaviour and physiology have continued to enhance the ability of researchers and scientists to use these strategies for the benefit of animals.

Some contemporary definitions of the Three Rs emphasise knowledge gains and welfare benefits along with minimising inhumane techniques – for example, replacement now often means using high-tech models and tools instead of animals such as in veterinary surgery education. When the number of animals being used is reduced, care is taken that the experimental design and statistical analysis are robust and add value to scientific knowledge. Refinement has become associated with advancing animal welfare through the use of the latest in vivo technologies alongside furthering understanding about the impact of welfare on animal studies such as identifying handling techniques that cause the least amount of distress and re-homing animals once experiments have concluded.

Rights: Public domain

Re-homing test animals

Where possible, ethical best practice for animal experimentation is to re-home test subjects once testing is concluded.

Uptake and legislation

The uptake of the Three Rs by the international academic community has been slow and variable. Two factors support continued and expanding uptake of the Three Rs – legislation and the growing acceptance in the scientific community through establishment of dedicated national centres and networks in many countries around the world.

The first Three Rs legislation was passed by the European Community in 1986 and updated in 2010. In the USA, public health and animal welfare regulations framed by the Three Rs require consideration of alternatives to animals. Many other countries also have Three Rs legislation. Dedicated Three Rs research centres began in Europe and the USA from the 1980s. Currently, there are institutions and digital networks in many countries. For example, NC3Rs (National Centre for the Replacement, Refinement and Reduction of Animals in Research) is a UK Government-funded national centre. The ECOPA website dedicated to the Three Rs began in 2000 (ECOPA 2023) and acts as an umbrella for European national platforms such as Norway’s Norecopa.

In Aotearoa New Zealand, there is no legal requirement to use the Three Rs in animal research, but the Ministry for Primary Industries (MPI) and the government encourage their use when animals are used in research, testing or teaching. It is expected that the Three Rs are considered when animal ethics committees review research proposals. MPI partners with the Australian and New Zealand Council for the Care of Animals in Research and Teaching (ANZCCART) to promote a New Zealand-specific Three Rs programme that:

• promotes their understanding and application
• profiles the contributions made using the Three Rs
• networks and liaises with international Three Rs centres.

Rights: Georgina Stewart and Sally Birdsall, ANZCCART, MPI

Animals of Aotearoa and animal ethics

Animals of Aotearoa: Kaupapa Māori Summaries and Exploring the Three Rs of Animal Ethics with Māori Ideas were developed with funding from the Australian and New Zealand Council for the Care of Animals in Research and Teaching (ANZCCART) and the Ministry for Primary Industries. The silhouette design was created for this project and is the copyright of Professor Georgina Tuari Stewart and Dr Sally Birdsall.