SPCA New Zealand
Advice & welfare

Replacement, Reduction, and Refinement: The '3Rs'

The 3Rs are ethical principles used to advance the welfare of animals used in research, testing, and teaching.

In New Zealand, animals are used in research, testing, and teaching for many different reasons. Research, testing, and teaching are often referred to as ‘RTT’ and include a variety of science-based activities. Research with animals can include understanding what wild fish eat in a specific ecosystem, assessing the impacts of exercise on the heart, or developing improved diets for aging companion animals. Testing with animals can include demonstrating the efficacy of a new worm treatment for cattle or determining the welfare impacts of a new animal trap. Teaching can occur in our secondary schools including through science fairs, in our tertiary institutions in biology courses, or for qualification for animal-based work in shelters, such as vet nursing.

Under Part 6 of the Animal Welfare Act, all use of animals in RTT must adhere to the ethical principles of the replacement, reduction, and refinement- the ‘3Rs’- to help ensure the welfare of animals used in RTT is protected.

So what are the 3Rs?


Replacement is the ethical principle which states that sentient animals should be avoided or replaced with nonsentient animals or non-animal alternatives in RTT. Some examples of replacement include:

  • Use of cell cultures or microchips in research and testing
  • Use of fake human skin in testing
  • Use of 3D models and computer simulations in teaching courses such as anatomy.
  • Using animal tissues available from another research project or a different source.


Reduction is the ethical principle which states the number of animals used should be the fewest number needed for RTT. Some examples of reduction include:

  • Using robust statistical analysis to determine the fewest number of animals needed for an experiment.
  • Increasing the number of students per animal ratio if animals are used in teaching.
  • Using the same control group in different experiments where this is applicable.


Refinement is the ethical principle that states procedures used in RTT or the animal’s environment are improved to ensure that negative states of welfare are minimised, and positive states of welfare are promoted. Some examples of refinement include:

  • Using food rewards to encourage a rat to complete a maze task.
  • Using lighter-weight GPS tags which are attached to wild animals to track their movements.
  • Training staff to handle animals in ways that reduce stress such as using tubes to move mice rather than picking them up by hand.
  • Housing animals in species-specific housing that promotes their natural behaviours, such as allowing rats to dig and climb or providing mice with a separate room for toileting.

SPCA's position on the 3Rs

SPCA recognises the 3Rs as important principles to protect and advance the welfare of animals used in RTT. We support efforts to reduce the number of animals used in RTT and refine procedures and the animal’s environment. It is essential that advances in the principle of replacement include more funding for the development of technology to avoid the use of animals for RTT. SPCA also supports the training of researchers and teachers in the use of alternatives to animals, especially for technologies that are just as good or equivalent in achieving outcomes.

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