Check this link on new considerations when measuring pain:https://www.nature.com/articles/s41684-019-0405-8
Check this link on new considerations when measuring pain:
This is a very interesting website that shows the achievements of the National Committee for the Protection of Animals Used for Scientific Purposes. The link is: http://english.ncadierproevenbeleid.nl. They have created very useful guidelines on pain detection, genetically modified animals and alternatives to standard methods of killing.