What is a humane endpoint in animal research?

• A. A point at which an experiment is terminated to prevent unnecessary suffering.
• B. A threshold for maximum data collection.
• C. A measure of long-term survival.
• D. A method of euthanasia after study ends.

Answer: (A)

A humane endpoint is a predefined point at which an animal is euthanized or removed from a study to prevent or minimize suffering. This aligns with Refinement in the 3Rs, aiming to stop pain or distress before it becomes unacceptable. Endpoints are set in advance using objective signs—such as significant weight loss, inability to eat or drink, respiratory distress, severe lethargy, or other clear clinical indications—so that welfare is protected and data quality remains reliable. It’s about stopping suffering during the study, not simply about data collection thresholds, long-term survival, or euthanasia after the study ends.