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Minimising the Harm Done to Animals

Used in Science - The 3Rs

Animal-based scientists are required by law to make sure that they keep any pain, suffering or other harm they cause to the animals they use for research , teaching and testing as low as possible. The 3Rs Principle is applied at the planning stages before any direct work with animals begins. Its purpose is to help scientists to minimise the invasiveness, unpleasantness or noxiousness of anything they do to animals. The 3Rs Principle is a practical guide to scientists. It is designed to ensure that:

  • animals which might suffer are only used when necessary (Replacement),
  • that no more and no fewer animals are used than are required to achieve the objectives of the work (Reduction), and
  • that if any noxiousness is caused during the work, it is kept as low as possible (Refinement).

Click on the following headings to find out more. Even more information can be obtained within each section by clicking on highlighted words.

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The 3Rs

Replacement, Reduction & Refinement

Replacement means that animals should not be used at all if the same research, teaching or testing aim can be achieved in other ways. The word "animal" refers to those higher order animals that are capable of suffering or feeling pain. So the first question scientists must ask themselves at the planning stage of a study is "Do I need to use higher order animals at all?" If the answer is "Yes" then Reduction and Refinement must be applied.

means keeping the number of animals used to the minimum necessary to achieve the research, teaching or testing purposes of the work. This avoids using unnecessarily large numbers of animals. But it is equally important to avoid using too few animals. If not enough animals are used it will not be possible to interpret the results, and the animals used would have been wasted. So the second question scientists must ask is "What is the lowest number of animals needed for this work?"

refers to keeping any pain, suffering or other harm which may be caused as low as possible for each and every animal used in the work. This means that every aspect of the work must be reviewed carefully and great care taken to minimise any noxious effects on the animals. Thus, the third question scientists must ask is "How can I minimise the noxiousness of every aspect of this work?" It is worth noting that many studies cause very low or no pain, suffering or other harm to the animals involved, while others do indeed have noxious effects.

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Assessing the invasiveness, severity or noxiousness of a scientific manipulation The invasiveness, severity or noxiousness of any proposed research, teaching or testing procedure must be given very careful consideration during the planning stages of the work, for two reasons.

First, it is necessary to anticipate the extent of pain, suffering, distress or lasting harm that might be caused to the animals by each part of the proposed procedure, in order to work out the best ways to keep any noxiousness as low as possible using refinement strategies.

Second, it is necessary to balance the expected levels of noxiousness against the anticipated benefits of the work in what is called a Harm-Benefit Analysis. The aim of this is to make sure that any harm is the lowest that is practically feasible and that the benefits are the greatest that can be reasonably achieved. The benefit must outweigh the harm by the greatest feasible margin for the work to proceed. It is the responsibility of both the animal-based scientists who prepare each research, teaching and testing proposal and the Animal Ethics Committee that reviews it to do harm-benefit analyses.

Noxiousness Scale

To help with this process various invasiveness, severity or noxiousness scales have been developed world-wide. These help animal-based scientists work out what the negative impact of a proposed procedure is likely to be on the animals. While no such formal criteria exist in Australia, Animal Ethics Committees usually classify animal experiments in a similar manner.

Note that the higher the noxiousness of a procedure, the greater the anticipated benefits must be before it can be approved. For specific examples at each level of noxiousness click on the relevant grade.

Grade O    No suffering or noxiousness.
Such procedures would not usually require justification in terms of expected indirect or direct benefits to animals, people or both.

Grade A    Little suffering or noxiousness.
Such procedures would requirejustification regarding the expected indirect or direct benefits to animals, people or both.

Grade B    Moderate suffering or noxiousness.
Such procedures would requiregood justification regarding the expected direct benefits to animals, people or both.

Grade C    Severe suffering or noxiousness.
Such procedures would require strong justification regarding the expected direct benefits to animals, people or both.

Grade X    Very severe suffering or noxiousness.
Such procedures would require the most exceptional justification and would be permitted only very rarely.

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How much suffering or noxiousness is caused by research, teaching and testing procedures in New Zealand?

In New Zealand the vast majority of scientific procedures produce little or no suffering or noxiousness. Nevertheless, a significant percentage of procedures are given noxiousness ratings of "C" or "X" despite careful application of the 3Rs. Such work can only be undertaken if those doing it can provide strong justification for "C" rated procedures and the most exceptional justification for "X" rated procedures (see Balancing Harm and Benefit). A detailed breakdown of these figures is available from the National Animal Ethics Advisory Committee.