A humane endpoint is, effectively, a limit to the level of suffering an animal can experience within a given scientific procedure. It is a defined point at which an experimental animal’s pain and/or distress is either ended or reduced, within the context of the scientific endpoints to be met. Actions to end or reduce suffering include humane killing, removal from the study, provision of analgesia, or any other appropriate measure to reduce suffering such as heat pads or dietary supplements. Death or severe morbidity as an endpoint should always be challenged in any field of research.
Under UK legislation, the responsibility for the implementation of humane endpoints sits with the personal licensee. However, discussion with ‘named persons’ and the AWERB will help to identify appropriate criteria for humane endpoints, and when to implement these, which can be included in the project licence application.
Experimental protocols should be designed to allow for the earliest possible alleviation of suffering. This may require a shift towards ‘mechanism driven’ (biomarker or pathway specific) experimental endpoints in some disciplines rather than phenotypic or disease driven endpoints. It may be argued that more useful data can be obtained from an animal not experiencing severe morbidity or imminent death, even if they are being used to model (or test potential therapies for) severe clinical disease. For ongoing studies, it is important from time to time to reflect on current endpoints and to consider whether further refinements could be applied.
The AWB/AWERB should ask for explanations of humane endpoints, including how they are defined, refined and implemented. They can also ask to see, and discuss, animal ‘fate’ data, including a breakdown of animals humanely killed as part of the experiment, found dead, killed because they are close to a humane endpoint, or because they are not needed (surplus). This will allow the establishment to monitor wastage, identify where endpoints may need to be revised and see where additional welfare monitoring should be applied.