Reduction

The R for Reduction concerns initiatives that focus on reducing the number of animals used per experiment. This can be achieved, for example, by sharing laboratory animals from 'control groups' or by using 'historical controls'. 

Furthermore, new statistical analysis methods can calculate exactly how to obtain reliable results with as few animals as possible, provided that you determine in advance exactly what effect you want to measure. The use of modern measuring instruments, such as an MRI scanner, which can be used to monitor the tumour growth of a single test animal in multiple stages instead of using new animals for each stage, can also help to reduce the use of test animals. 

You can read more about the 3Rs on the website of the 3Rs Centre Utrecht.