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The 3R principle

Animal experiments are indispensable in biomedical research, only with the help of experimental animals can complex processes and interactions in the living organism be detected and understood. A large number of scientific findings can be attributed to results from animal experiments. In this respect, animal experiment-based research creates an important basis for biomedical progress in Germany.

All scientists working in animal experiments are aware of the great responsibility they carry for the welfare of the experimental animals. Although animal experiments are essential in research, there is consensus that this should be kept to a necessary minimum. A guideline is the ethical principle of "3R": Replace, Reduce and Refine. The three terms were coined by two British researchers, zoologist William Russell and microbiologist Rex Burch, and published in 1959 in their book "The Principles of Humane Experimental Technique". The principles of action described therein are intended to limit the number of experiments and reduce the suffering of the animals used to an indispensable level. Consistent implementation of the 3R principle in all areas of animal research is the prerequisite for animal experiments to be approved by the responsible statutory authorities.

The following principles are used in the planning and implementation of animal experiments in the sense of 3R:


If possible, animal testing will be replaced by alternative methods. It is always checked whether it is sufficient to answer the scientific question, by using simple organisms such as bacteria or invertebrates or to use cell/tissue cultures, computer models or other substitute methods.


The number of laboratory animals is reduced to a necessary minimum. A clever design of the experiment and statistical and methodical optimizations contribute to this. Suitable animal models are carefully selected based on experience. By centralizing the results from animal experiments and good coordination between scientists, it is prevented that similar experiments are made several times.


The animals must be kept in an appropriate manner, so with enough space and in an environment that promotes their well-being. The constant improvement of examination methods, such as anesthesia, anesthetics and special animal training, reduces stress and suffering as much as possible. Also, a good and sound training of the experimenters leads to an improvement of the experiments and gives benefit to the experimental animals by refining theirs surrounding as well as the procedure they have to undergo. In addition to the established LAS course for non-human primates at the DPZ, in which the Department of experimental animal science is significantly involved, the newly established Skills Lab gives the opportunity to learn and refined a number of interventions and applications first on the model before they are used in the experiment.