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Petri Dishes

The 3Rs in
animal research


Under EU Directive 2010/63/ researchers must use non-animal alternative methods whenever they are possible. Every research project that makes use of animals must be authorised before it can start and it must include a scientific explanation of why animal research is needed in the project. The scientists must show that the each of the 3Rs (replace, reduce, refine) have been taken into consideration and outline the number of animals that will be used and the level of suffering that they are expected to experience.


A project proposal is evaluated through a harm-benefit analysis by the Competent Authority in each EU Member State, which will then decide whether to grant the license or not.

What is being done to replace and reduce the use of animals in research?


  • Zebrafish larvae can be used to replace animals such as mice, rats and guinea pigs in the study of the pharmacological effects of a molecule in an intact organism. This makes it possible to assess compounds early in the drug discovery process in lower-order animals (such as zebrafish), instead of rodents.
    For instance: Studying the effects in a complex organism makes the early selection of compounds much more reliable, lowering the overall number of mice or rats used in subsequent research phases.

  • The replacement of monkey kidney primary cells with a cell line for the testing of polio vaccines, led to a reduction in the number of animals used.

  • A safety test, replaced the use of monkeys, for three new monoclonal antibodies used to prevent the spread of infection.


  • Computer models have been developed which model human physiology. In some cases, these models can replace animal models to show whether a drug reaches its target, and how long it takes for it to be absorbed, distributed, metabolised and eliminated by the body. This can significantly reduce the number of animals used.


  • Measuring the effects of anti-cancer molecules without inducing disease in an animal model. Some targets for anti-cancer drugs have specific measurable effects in normal tissues. This can allow researchers to measure their effectiveness in animals without the need to induce tumours, as well as reduce the number of animals needed for a study.
    For instance: In a cancer study, to look for activity of a number of potential drugs, blood pressure was monitored in a total of 12 normal rats. This replaced use of 800 mice with tumours that would previously have been required.

  • A method for keeping muscle cells from dogs healthy for two weeks, instead of 24 hours, has allowed many more compounds to be tested on cells supplied from a single dog.

Test Tubes

Why are large number of animals used in biomedical research if the 3Rs are being implemented?

The large number of animals still used in research reflects the fact that alternative methods are not yet available for many areas of biomedical research. However, as part of all research project licence applications, researchers must consider whether the number of animals used can be reduced by referring to the latest best practice, and how any pain or discomfort can be kept to a minimum.

Is there an alternative model for all biomedical research? If not why not?

No. There are alternatives such as in vitro experiments or computer modelling, but they are not yet sophisticated enough to completely replace every aspect of animal research. Even when used, some alternative methods use knowledge provided from research using animals and materials sourced from animals and the results are then verified using animals.

Also, to study and develop animal medicines the use of animals, usually dogs, is fundamental. Dogs, cats and other companion animals suffer from cancers, heart diseases, diabetes, joint disease and many other conditions. Research involving these and other species enables the development of new safe and effective veterinary medicines that improve the health and welfare of animals worldwide.

Why monkeys cannot be replaced today:

  • To complete safety evaluation for some medicines in development, monkeys are required as the safety of some molecules cannot be evaluated in other animal species such as rats or dogs.

  • For some cases, only monkeys are similar enough to humans to have reliable results.

  • For more information on see the EARA page on the use of monkeys in research 

Isn’t funding to seek alternatives to animals negligible compared to research using animals?

There are many initiatives to fund alternatives to animal testing, such as the project VAC2VAC that aims to develop and validate methods for testing both human and veterinary vaccines without using animals.

There is also an EU pilot project that aims to harmonise the approach to training in the 3Rs to advancing animal welfare and scientific quality. Two dedicated e-learning training modules are also being developed for alternative (non-animal) approaches.

Collaboration between industry and academia also exists to solve and fund scientific challenges on the 3Rs, for instance the CRACK IT Challenges by NC3Rs.

What are you doing to protect animals from unnecessary experiments/pain?

The use of animals in the EU is covered by Directive 2010/63/ on the protection of animals used for scientific purposes. Under this directive, animals can only be used in research when there is a convincing scientific justification, when the expected benefits of the research outweigh the potential risks in terms of animal suffering and when the scientific objectives cannot be achieved using non-animal alternative methods. Only projects that fulfil these requirements are authorised.

See also the EARA page on severity assessments

What is being done to avoid the duplication of testing of animals in the EU?

Across the EU, a non-technical summary of every licensed project that uses animals is required. In this way, researchers can also become acquainted with all animal tests that have been licensed and will be carried out. The European Commission has recently drawn up a proposal to collect and publish all the non-technical summaries and the results of the retrospective assessment of all licensed projects in all Member States in a central database.

In the Netherlands, for instance, unnecessary duplication of animal testing allows the possibility to retrospectively assess animal tests on the results achieved. This retrospective assessment is legally required for all tests on monkeys and tests with serious distress, but can also be imposed by the Central Committee on Animal Testing (CCD) for other animal tests. A non-technical summary of every licensed animal testing project is published on the website of the CCD.

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