Humane endpoints must be decided before an experiment begins and outlined in a project licence application. They can’t be decided on an ad-hoc basis but should be monitored and reviewed throughout an experiment and changed if needed.  

In the UK, if researchers believe they need to go beyond the approved level of animal suffering, the Home Office must be contacted immediately for special permission. They may allow a temporary increase in suffering for up to 14 days.  

During those 14 days, a harm-benefit analysis will be conducted and the project licence permanently updated if it’s deemed the benefits outweigh the harm to the animals.  

How is a humane endpoint decided? 

When deciding on what the humane endpoint of an experiment will be, researchers will consider: 

• The level of pain and discomfort the procedure will likely cause the animals involved. 

• How frequently they need to check on the animals and what signs to look for. 

• Whether treatment is enough as an endpoint, or whether euthanasia is the preferred method. In the UK, a Schedule 1 killing method will likely be used to euthanise.  

• Information on how endpoints were monitored, recorded, and applied should be included when publishing study results.  

How do researchers decide they’ve reached the humane endpoint?

To determine humane endpoints, researchers need to already know: 

• The normal behaviour and physiology of the animals being used. 

• At what point a humane endpoint will be applied. 

• Indicators in the animal the threshold has been met for humane endpoint to be applied. 

Researchers must also ensure that the humane endpoints decided on are: 

• Reproducible, easy, and efficient to monitor 

• Will not interfere with the procedures before necessary (potentially leading to more animals being used) 

• Relevant to both the animals and the procedures.   

Signs an animal has reached the humane endpoint of an experiment fit into two categories: physiological and behavioural. Depending on the species and procedures taking place, these can vary.  

Physiological indicators include:

• Difficulties breathing
• Changes in blood count 
• Dehydration 
• Changes to heart rate 
• Weight loss 
• Hormonal and biochemical changes 

Behavioural indicators include:

• Changes in activity level 

• Unusual posture 

• Aggression 

• Unusual responses to handling 

• Changes to grooming habits 

• Vocalisation 

• Changes in appetite and thirst 

We believe the ultimate way to protect animals is to replace their use entirely. We strive to empower researchers to develop, and use, alternatives to animal research.  

We believe through community, the right legislation, and dedication, we’ll see a future where no animal suffers for science.