3R Principle

3R principle is a concept introduced by 2 researchers, Russel and Burch, and published in 1959 in a book entilted "The principles of humane experimental technique" 

Terms corresponding to 3R are «  Reduce, Refine, Replace»

According to this principle, each researcher must:

  • use all procedures which improve housing and daily life of experimental animals, apply up-do-date methodologies and administrate analgesia 
  • justify necessity of working with an animal model, explaining the expected benefits and clearly notifying constraints for experimental animals
  • justify the choice of a particular animal model and demonstrate there is no possible alternative.

Academic institutions undertake to promote 3R principle application and to improve culture of care in animal experimentation.

Few examples:

Reduce means

Use the minimal statistically valid number of animal in each scientific protocol

  • by working with statisticians to define the best methodology and design to use
  • by promoting translationnal studies and bioimaging technology

Refine means 

Always improve animal welfare and minime constraints suffered by experimental animals

  • by promoting the use of less-invasive or non-invasive procedures
  • by administrating appropriate analgesia and improving surgical procedures
  • by carefully following animal welfare and defining clear human endpoints 

Replace means  

Use alternative model

  • use cell or organ cultures
  • use invertebrates instead of vertebrates
  • use computational modelization

The Principles of Humane Experimental Technique, W.M.S. Russell and R.L. Burch


Russell and Burch's 3Rs Then and Now: The Need for Clarity in Definition and Purpose


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