Suppose, for a particular purpose, we cannot use replacing techniques. Suppose it is agreed that we shall be using every device of theory and practice to reduce to a minimum the number of animals we have to employ. It is at this point that refinement starts, and its object is simply to reduce to an absolute minimum the amount of distress imposed on those animals that are still used.

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

Every researcher subjecting animals to research, testing or teaching has the responsibility to implement refinement alternatives, one of the three R’s described by Russell and Burch. The goal of refinement is to minimize distress in animals in research.

A wide array of refinements can be implemented. Some involve improvements in living quarters: Social animals might be provided with compatible companions, or caging modified to permit and encourage species-typical behaviors (e.g., foraging, climbing, grooming, and burrowing). Others involve less stressful handling, such as when animals are trained to cooperate for procedures rather than being subjected to enforced restraints (a mouse trained to voluntarily drink from a syringe and thereby ingest a particular substance, or a monkey induced through positive reinforcement to offer a limb for a blood draw in exchange for a reward).

Other forms of refinement include:

  • Use of non-invasive imagine techniques such as magnetic resonance imaging (MRI) and computed tomography (CT);
  • Use of the anesthetic, analgesic and tranquilizing drugs in the proper dose and administration to effectively alleviate pain or distress;
  • The development and use of "humane endpoints" - defined by one source as "the earliest indicator in an animal experiment of (potential) pain and/or distress that, within the context of moral justification and scientific endpoints to be met, can be used to avoid or limit pain and/or distress by taking actions such as humane killing or terminating or alleviating the pain and distress."


Refinement techniques represent a key focus of AWI, as there is much that can be done immediately to improve the welfare of animals in research. AWI offers a plethora of complimentary materials on refinement options to those who work with animals in research, and hosts an on-line Laboratory Animal Refinement and Enrichment Forum to promote discussion and sharing of information on refinement techniques and practical experiences among laboratory personnel. AWI also provides grants to support research into the development of further refinement techniques.