Severity degree 3 experiments

4. Four severity grades

In Switzerland, animal experiments are classified into four categories of stress or constraint. Severity grade 0 means the animals are not exposed to any stress. Observation studies are an example of this. Forty percent of laboratory animals in Switzerland are used in severity grade 0 experiments. Severity grade 1 corresponds to mild stress (e.g. blood sampling) and severity grade 2 to moderate stress (e.g. surgical procedure under anaesthesia). Highly stressful animal experiments (severity grade 3) are only used for research into serious diseases (for example, multiple sclerosis or Parkinson’s). In Switzerland, fewer than 3.5% of all animal experiments were classified as severity grade 3 in 2019. In these studies, almost 95% of the animals were mice or rats.