The Three Rs: Replacement, Reduction and Refinement

In one line

Replacement, reduction and refinement are the three principles of humane experimental technique, and Indian law adopted all three in 1960 without using the words.

In exam wording: the three Rs are replacement, meaning the use of a method that avoids using a living animal where the same result can be obtained; reduction, meaning the use of the smallest number of animals, or of smaller and less sentient animals, consistent with obtaining the result; and refinement, meaning the minimisation of pain, suffering and distress in the animals that are used; and each is reflected in Indian law, replacement in section 17(2)(d) of the Prevention of Cruelty to Animals Act 1960, reduction in section 17(2)(e), and refinement in section 17(2)(b), (c) and (g) and in rule 9 of the Breeding of and Experiments on Animals (Control and Supervision) Rules 1998.

What each of the three means

Replacement. Do not use an animal at all if the question can be answered another way. Cell culture, computer modelling, tissue from an animal already killed for another purpose, human volunteers where the risk permits, and, in teaching, a book, a model or a film.

Reduction. Use as few animals as the result requires, and where the choice exists use a species lower in the scale of sentience. Better experimental design, sharing of animals between studies and statistical planning all belong here.

Refinement. Where an animal is used, reduce the pain, suffering and distress it undergoes. Anaesthesia and analgesia, humane end points, better housing and handling, and humane methods of destruction.

Where each sits in Indian law

Replacement: section 17(2)(d). The Committee's rules shall be designed to secure that experiments on animals are avoided wherever it is possible to do so, "as for example, in medical schools, hospitals, colleges and the like, if other teaching devices such as books, models, films and the like may equally suffice".

Reduction: section 17(2)(e). That experiments on larger animals are avoided when it is possible to achieve the same results by experiments upon small laboratory animals like guinea-pigs, rabbits, frogs and rats.

Refinement: section 17(2)(b), (c) and (g). That experiments are performed with due care and humanity and, as far as possible, that experiments involving operations are performed under an anaesthetic of sufficient power to prevent the animal feeling pain; that animals so injured under anaesthetic that recovery would involve serious suffering are ordinarily destroyed while still insensible; and that animals intended for experiments are properly looked after both before and after.

A fourth idea, in section 17(2)(f). That, as far as possible, experiments are not performed merely for the purpose of acquiring manual skill. That is neither replacement nor reduction but a limit on purpose.