Animal usage report for 2025
The number of laboratory animals used for research purposes by the Max Delbrück Center and reported to the Berlin State Office for Health and Social Affairs has declined once again. In total, researchers used 23,878 animals in experiments in 2025 aimed at developing new human therapies. In 2024, the center reported using 31,517 animals – the lowest number in ten years.
In 2025, most of the animals were mice – 20,802 – which was 5,262 fewer than in the previous year. The other animals included rats (1,521), zebrafish (1,406), and naked mole-rats (149), which are classified in the statistics as “other rodents.”
The experiments were conducted by researchers at the Max Delbrück Center as well as collaborating groups from Charité – Universitätsmedizin Berlin, the Leibniz Research Institute for Molecular Pharmacology, the Berlin Institute of Health at Charité, the DESY research center (Deutsches Elektronen-Synchrotron) at the Zeuthen site, and the biotechnology company T‑knife, a spin-off of the Max Delbrück Center located on the Berlin-Buch campus.
Most laboratory animals were subjected to minimal stress
According to the scientists, 4,933 of the animals used were not genetically modified. A total of 17,837 animals were genetically modified without showing pathological symptoms. Another 1,108 animals were modified in such a way that they developed symptoms. By modifying their genomes in a targeted way, the researchers were able to gain a better understanding of physiological processes in both healthy and diseased states.
Almost half of the animals (10,644) were killed for scientific purposes and experienced minimal stress. Among the remaining laboratory animals (a total of 13,234), the level of stress was generally low according to the researchers. For 3,579 animals it was classified as moderate, and for 184 animals as severe.
Regardless of the level of stress, researchers at the Max Delbrück Center are required to reduce any discomfort experienced by the animals as much as possible, through appropriate pain relief, for example. They must also weigh the negative impact on the animals against the expected medical and scientific benefit.
All researchers must adhere to the 3R rule – replace, reduce, refine. It stipulates that they must minimize the number of laboratory animals used, limit pain and suffering, and use alternative methods whenever feasible.
Several reasons for the declining numbers
The fact that practicing 3R is becoming increasingly feasible is demonstrated by the steady decline over the years in the number of laboratory animals used at the Max Delbrück Center. This is particularly due to technological advances. Many of the center’s research groups that have been established in recent years have specialized in bioengineering or data science for example – fields that require fewer laboratory animals.
Additionally, other teams that in the past have used large numbers of animals have been dissolved for reasons that include group leaders having retired. And some groups now increasingly work with organoids – tiny organ models grown from stem cells.
The Max Delbrück Center cannot completely do away with animal testing for the foreseeable future. Scientists at the center unanimously emphasize that for many research questions in the life sciences, there is currently no alternative. The human body is extremely complex; its functions – and the effects of potential new drugs – are almost always influenced by interaction among different cells, tissues, and organs. This interplay can often only be studied in a living organism.
The Max Delbrück Center is regarded as one of the pioneers in open communication regarding animal testing in science. Among other activities, it was one of the first signatories of the nationwide “Transparent Animal Testing Initiative.” In addition, the information initiative “Understanding Animal Testing” honored the center for a second time in 2024 for its exemplary communication regarding animal research. Since 2012, the Max Delbrück Center has continuously set standards in public education about animal testing, the honorary citation states, with a clear focus on active dialogue with the public.
Text: Anke Brodmerkel
Further information
Contact
Tabea Rauscher
Head Communications and Marketing
Max Delbrück Center
+49 30 9406 – 2140
tabea.rauscher@mdc-berlin.de or presse@mdc-berlin.de
- Max Delbrück Center
The Max Delbrück Center for Molecular Medicine in the Helmholtz Association aims to transform tomorrow’s medicine through our discoveries of today. At locations in Berlin-Buch, Berlin-Mitte, Heidelberg and Mannheim, our researchers harness interdisciplinary collaboration to decipher the complexities of disease at the systems level – from molecules and cells to organs and the entire organism. Through academic, clinical, and industry partnerships, as well as global networks, we strive to translate biological discoveries into applications that enable the early detection of deviations from health, personalize treatment, and ultimately prevent disease. First founded in 1992, the Max Delbrück Center today inspires and nurtures a diverse talent pool of 1,800 people from over 70 countries. We are 90 percent funded by the German federal government and 10 percent by the state of Berlin.
