The 3Rs (Three Rs) of replacement, reduction and refinement have guided research involving animals through the use of humane principles around the world. The 3Rs have been adopted in various ways through policy, guidelines and legislation. In Australia, people involved in animal research are trained to understand and implement the 3Rs. Researchers must demonstrate adherence to the 3Rs as well as other requirements (e.g., justification, likelihood of success) when submitting projects for consideration by an animal ethics committee.
The 3Rs of replacement, reduction and refinement were developed and published by scientists Russell and Burch in 1959 to encourage researchers to conduct more humane animal research . These principles help ensure the welfare of animals used in research is prioritised and that animals are recognised as sentient beings. Sentience is the capacity for animals to be aware of their surroundings, capable of experiencing positive and negative emotions, and the ability to process information relating to changes in their environment.
The 3Rs are:
- Replacement of the use of animals with alternative techniques, such as human cell and tissue culture, biological agents (e.g., yeasts and other organisms), inanimate models, human volunteers, video and computer aids and mathematical modelling (e.g., virtual populations).
- Reduction in the numbers of animals used, such as through applying best practice statistical methodology and, where animals have already been used, sharing animal tissues with other researchers. Reduction may also be achieved through using cell and tissue cultures.
- Refinement of procedures to improve the welfare of animals used in research, such as through the use of pain relief, avoiding adverse effects, increasing competency of researchers and animal carers, and enhancement of housing conditions.
Those involved in the use and care of animals used in research in Australia are required to apply the 3Rs . Despite continuous improvements having been achieved, implementation of the 3Rs varies within and across organisations. A major impediment has been the limited development and availability of resources to achieve the goals of the 3Rs . For example, to improve refinement, more substantial investment is required to develop and implement more humane approaches for animal housing, handling and pain management associated with invasive procedures.
There are also other impediments to fully implementing the 3Rs such as resistance to or delays in making necessary changes to regulatory and procedural processes that would allow greater implementation of the 3Rs. For example, although some progress has been made in using non-animal methods for safety testing of a few chemical compounds, government regulatory standards still require animal trials to be conducted for the registration of other products.
A survey of researchers in Europe found that greater emphasis was placed on refining techniques especially in relation to pain management, compared to reduction or replacement . This finding is concerning as it indicates a lack of commitment or belief that the focus should be on replacing animals used in research, which would in turn negate the need to consider reduction or refinement strategies.
In the USA, UK and Europe, the uptake of the 3Rs has been increased through the establishment of 3R centres which promote and support the 3Rs . The RSPCA has advocated over many years for the establishment of a centre for non-animal alternatives in Australia. This could achieve significant progress in replacing the use of animals in research, thus achieving significant gains in improving animal welfare and attracting international recognition for Australia’s work to implement the 3Rs.
 Russell WMS & Burch RL (1959) The Principles of Humane Experimental Technique. London, UK: Methuen
 NHMRC & Australian Research Council (2013) Australian Code for the Care and Use of Animals for Scientific Purposes. Commonwealth of Australia, Canberra
 NHMRC (2019) Information Paper: Implementation of the 3Rs in Australia. Commonwealth of Australia, Canberra.
 Franco NH, Sandoe P, Olsson IAS (2018) Researchers attitudes to the 3Rs – An upturned hierarchy? PLoSONE 13(8): e0200895.
 Burden N, Chapman K, Sewell F et al (2015) Pioneering better science through the 3Rs: An introduction to the National Centre for the Replacement, Refinement, and Reduction of animals in research (NC3Rs). Journal of the American Association of Laboratory Animal Science 54(2):198-208