The experimental animals used by the MPI-CBG in 2020 and registered with the authorities are shown in the pie chart. The most frequently used experimental model in 2020 was the mouse (85 %), followed by zebrafish (14 %). The majority of procedures carried out in 2020 were classified as mild (86%), and the proportion of moderate procedures was only 1%. We do not perform any procedures that are classified as severe. The proportion of 'non-survival' procedures carried out under general anesthesia and the proportion of animals used for organ and tissue removal after humane and painless euthanasia, was 12%. Experimental animals that were painlessly euthanized for the removal of biological material (e.g. cells, tissues and organs) were not subjected to any other form of stress or procedure. Although the majority of our experiments cause little or no pain, we strive to minimize any distress by monitoring the animals' well-being daily (or continuously if needed), using predefined protocols to assess animal health and humane endpoints, and using analgesics and other measures (e.g. stress-free environment, gentle handling) to ease distress.

The types of experiments according to severity categories are defined by EU Directive 2010/63/EU (http://www.eara.eu/assessing-the-severity-of-animal-procedures). Definitions are shortly summarized below:

Non-recovery:
Procedures which are performed entirely under general anesthesia from which the animal shall not recover consciousness. Includes animals euthanized painlessly to obtain cells or tissues for cell culture (no experiments performed).

Mild:
Procedures on animals as a result of which the animals are likely to experience short-term mild pain, suffering or distress, as well as procedures with no significant impairment of the well-being or general condition of the animals. Typical examples may be a single injection or removal of a small tissue sample for genotyping purposes.

Moderate:
Procedures on animals as a result of which the animals are likely to experience short-term moderate pain, suffering or distress, or long-lasting mild pain, suffering or distress as well as procedures that are likely to cause moderate impairment of the well-being or general condition of the animals. Typical examples are simple survival surgeries such as introducing an imaging window for microscopy.

Severe:
Procedures on animals as a result of which the animals are likely to experience severe pain, suffering or distress, or long-lasting moderate pain, suffering or distress as well as procedures, that are likely to cause severe impairment of the well-being or general condition of the animals. We have never performed a procedure within this category.