We support the use of a severity classification system as it helps to better capture the impact of scientific procedures on the health and well-being of experimental animals.

A thoroughly conducted severity degree classification is an essential tool for the improvement of the 3R principles as it helps in advance to define humane endpoints and to assess on a project-by-project level to assess progress in refinement.

In countries where the use of severity classification systems is not yet mandatory we recommend the voluntary use of such systems by the members of the scientific community.

We do recommend the following cornerstones of a severity degree system:

• We recommend the categorization of severity degrees with the inclusion of a category covering “no pain, no distress”. The categorization should be made on factually based criteria.
• Achievement of the same regulatory standards on a global level would be highly desirable. The standards have to be transparent and science- and evidence based and developed on a peer reviewed process.
• All animals, whether genetically modified or not, are subject to the same general principles that govern the ethical treatment of animals, including the 3 Rs.