Defining the 3Rs

The Principles of Humane Exerimental Techniques, written by William Russell and Rex Burch, were published 60 years ago.  This laid out the principles of the Refinement, Reduction and Replacement (3Rs) as a framework for performing humane animal research.  The 3Rs are internationally accepted principles for the ethical consideration of animals in research. 

Refinement:  methods which minimize pain and distress and/or improve welfare of the animals required.

Reduction:  methods which minimize the numbers of animals used.

Replacement:  methods which avoid, or replace, the use of animals

  • Full replacement refers to replacing living animals with non-animal methods.
  • Partial or relative replacement refers to replacing animals with animals that are not considered capable of experiencing pain/distress