Endpoint matrix: a conceptual tool to promote consideration of the multiple dimensions of humane endpoints.

This paper proposes a framework to support appropriate application of endpoints in animal experiments. It is recommended that unpredicted endpoints should be explicitly considered alongside scientific endpoints and justifiable endpoints as the three types of endpoint which comprise the "humane." We suggest there is a need for clear identification of each type of endpoint and an understanding of the interactions between these types. The use of an "endpoint matrix" during study planning is proposed to promote methodically sound and consistent definition, determination, and detection of unpredicted, scientific, and justifiable endpoints in animal experiments. It is claimed that the further development and use of this tool will support a more effective and harmonized practical application of humane endpoints for all animal use in line with best practice recommendations.