Reduction and Refinement of Genetically Altered Mouse Breeding: Controlling Quality and Quantity According to Experimental Needs

The mouse is currently the most widely used animal model for scientific research worldwide. In Europe, statistical data show that half of all mice used in research are genetically modified, and that 60% of the transgenic mice produced are ultimately not used. Optimizing production strategies is therefore essential to minimize the production of animals that will not be included in research. In this article, we examine the key components required for the rigorous management of genetically modified lines, organized under the acronym DOPPUME: Define, Obtain, Protect, Produce, Use, Manage, and Exchange. The first step is to clearly define the model in accordance with the scientific objective and strictly control its genetic characteristics, including both the genetic background and the engineered modification. Ensuring the stability of these parameters is crucial for maintaining continuity between studies and preventing genetic drift. The article also provides tools to support the clear definition of production goals based on planned experiments and to estimate production needs as accurately as possible, accounting for the types of crosses and breeding schemes involved. Emphasis is placed on producing only what is necessary and on implementing proactive, rather than reactive, colony management. This framework is fully aligned with the 3Rs principles (Replace, Reduce, Refine) by promoting a responsible, rational, and optimized use of mouse models in research. © 2026 Wiley Periodicals LLC.