Anhedonia - the reduced ability to experience pleasure - is increasingly recognized as a key indicator of poor welfare in animals, with cognitive bias tests and other behavioral measures now able to detect this state across many species.
Traditional welfare assessment focused on physical health parameters - disease, injury, body condition. Recognition that animals can experience sustained negative emotional states like anhedonia has transformed welfare science. An animal that is physically healthy but living in a barren, understimulating environment may still be experiencing chronic poor welfare through anhedonia. Cognitive bias tests and sucrose preference tests now give researchers tools to measure these states. The practical application is improving housing, social conditions, and environmental complexity to restore positive emotional states.