Euthanasia Methods in Invertebrates: A Critical Narrative Review of Methodological and Welfare Standards

Area of Science:

• Veterinary Science
• Animal Welfare
• Invertebrate Biology

Background:

• Growing use of invertebrates in consumption, pets, research, and zoos necessitates better welfare and clinical management understanding.
• Limited knowledge and absence of standardized protocols for invertebrate nociception, pain perception, and euthanasia.
• Existing euthanasia guidelines are often incomplete, anecdotal, and lack coverage of major invertebrate phyla.

Purpose of the Study:

• To critically evaluate existing invertebrate euthanasia methods and their welfare implications.
• To identify opportunities for refining current end-of-life procedures for invertebrates.
• To propose a practical, two-step approach for invertebrate euthanasia based on available literature.

Main Methods:

• Conducted a narrative literature review focusing on invertebrate euthanasia.
• Critically assessed existing euthanasia techniques, welfare implications, and potential refinements.
• Focused the review on the application of a proposed two-step euthanasia approach.

Main Results:

• Limited and scattered peer-reviewed, species-specific literature on invertebrate euthanasia.
• Many described methods are insufficiently studied or do not meet the definition of euthanasia.
• Effectiveness and humaneness of euthanasia techniques vary significantly across invertebrate taxa and life stages.

Conclusions:

• A two-step approach (anesthesia followed by central nervous system destruction) is proposed for invertebrate euthanasia.
• Substantial further research is required to validate and optimize humane end-of-life procedures for diverse invertebrate species.
• Addressing knowledge gaps in invertebrate welfare and end-of-life care is crucial.