What are the three Rs?
The 3Rs are the guiding principles for ethical practice in animal research. They stand for:
- Replacement: Replacement involves methods that avoid or replace the use of animal models. It can be further split into:
- Absolute replacement:
which for example includes the use of cell culture, organoids and
organs-on-a-chip, as well as computer modeling of novel pharmacological
- Partial replacement: which involves the use of invertebrates, that show a lower level of pain perception such as Drosophila melanogaster - a common fruit fly - or even bacteria.
Refinement aims to improve animal welfare by reducing or avoiding pain,
suffering and distress in animal experiments. This can be achieved by
improving animal husbandry in research facilities, or by finding less
- Reduction: Reduction refers to
methods that reduce the number of animals used per animal trial. The aim
is to minimize the total number of animals while maximizing the gained
knowledge per animal used at the same time.
For further details click below:
R.L. Burch and W.M.S. Russel1
In 1954 William Russel and Rex Burch, two outstanding british biologists, were instructed by the Universities Federation for Animal Welfare (UFAW)
to perform a systematic study about the ethical use of animals in
laboratory techniques. After finishing their work, Russel and Burch
decided to put more emphasis on this area, which resulted in their opus
magnum "The Principles of Humane Experimental Technique"2
they proposed the three Rs as a mean to achieve an end to animal
distress in research and thereby increase humanity of experimental
then scientists were hesitant to apply the principles described in this
book, since alternatives to animal studies in research were widely
regarded to be in an early phase of their development, and disparities
between sciences and humanities were increasing.
Still, over the
past few decades there has been an ever-increasing scientific interest
in these principles, accompanied by the rise of various modern animal
rights movements. This eventually led to the integration of the three Rs
into the EU legislative framework in the Directive 2010/63/EU.
means the substitution for conscious living higher animals of
insentient material. Reduction means reduction in the numbers of animals
used to obtain information of a given amount and precision. Refinement
means any decrease in the incidence or severity of inhumane procedures
applied to those animals which still have to be used."
-Russell and Burch: The Principles of Humane Experimental Technique, 19592
then, the three Rs have to be considered before performing animal
experiments. Before writing research proposals involving laboratory
animals, the following questions have to be answered first:
- Replacement: Is it possible to obtain the required information without the use of live animals?
- Reduction: Is it possible to reduce the number of animals while obtaining the same amount of knowledge?
Is there a way to improve the wellbeing of animals used in experiments,
e.g. by reducing distress, pain and suffering?
an increasing call for animal welfare in research, scientists from the
three Medical Universities of Austria established the RepRefRed Society,
an organisation which is now part of the global joint effort to promote
the three Rs in biomedical research.
Are you interested in joining us? Click here.
1Canadian Council on Animal Care
2Russell and Burch´s 3Rs Then and Now: The Need for Clarity in Definition and Purpose - Jerrold Tannenbaum, and B Taylor Bennett