Animal research in Germany
In 2025, 215,014 laboratory animals were used at the Max Planck Institutes. This figure includes 94.979animals that were used to obtain organ or tissue samples and were not subjected to any stress prior to their death. Compared to 2024 (262.101 animals used in experiments), the number of animals used in experiments fell by 18 percent. Rodents (mice and rats) accounted for the largest share of animals used in experiments (around 79.0 percent), followed by fish (18.5 percent). Other animal groups, such as birds (1.9 percent), were used as experimental animals to a significantly lesser extent at the Max Planck Institutes.
The Max Planck Society uses a significantly higher percentage of fish for its research than the national average, thereby fulfilling an essential requirement of the German Animal Welfare Act, which stipulates that vertebrates with the lowest possible level of organisation should be used for experimental purposes. However, the high proportion of fish is also due to their importance for basic research: zebrafish in particular have become a very important model organism for molecular and developmental biology and neuroscience. In terms of the type of use, 90.7 percent of all animals are classified as being used in basic research, in line with the scientific orientation of the Max Planck Society.
In 2025, 22 non-human primates were used in experiments requiring approval at our institutes.
Severity of the experiments
In 2025, most experiments conducted at Max Planck Institutes were low-severity (53.3 percent); the proportion of animal experiments with medium severity was 41.8 percent. Only 1.2 percent of experiments at Max Planck Institutes were classified as severe. The proportion of animal experiments carried out under general anaesthesia from which the animals did not regain consciousness was 3.7 percent.
The proportion of genetically modified animals in 2025 was 71 percent, representing a reduction of 6.7 percent compared to the previous year. Only 2.9 percent of all genetically modified laboratory animals experienced adverse health effects as a result. The vast majority of genetically modified animals (mostly rodents) showed no health abnormalities (97.1 percent).
Killing for scientific purposes
In 2025, 311,832 laboratory animals were killed painlessly for scientific purposes at the Max Planck Institutes. This figure includes animals already listed that were used for organ or tissue removal. None of these laboratory animals – predominantly rodents (87.5 percent) and fish (11.8 percent) – underwent any procedures or treatments during their lifetime. 52.4 percent of the animals were used to produce, breed and maintain genetically modified lines, which are an essential tool for biomedical research. The removal of tissue samples accounts for 30.5 percent.
Despite careful planning, it is unavoidable that animals will be obtained in the course of research activities that cannot be used directly in animal experiments. The Max Planck Society is very keen to keep this proportion (17.1 percent in 2025) as low as possible. Animals that cannot be used in animal experiments mainly come from genetically modified breeding lines. Due to the statistically random transmission of genetic changes in accordance with Mendel's laws, these animals do not all have the genetic characteristics required for the planned animal experiment. Such animals are produced in every breeding of genetically modified lines.
Researchers at the Max Planck Society use various strategies to reduce the number of these animals or to use them for other meaningful purposes. Through efficient breeding planning and cryopreservation of genetically modified lines, the number of unused animals was reduced by 22.9 percent compared to the previous year. This was achieved through cryopreservation of sperm and embryos from genetically modified lines, which made it possible to discontinue maintenance breeding. Despite this success, declines of this magnitude are not expected in subsequent years due to a lack of comparable technical solutions.
