Special issue: Cephalopod Biology
The identification and management of pain, suffering and distress in cephalopods, including anaesthesia, analgesia and humane killing☆,☆☆

https://doi.org/10.1016/j.jembe.2013.02.010Get rights and content

Abstract

From January 2013 scientific projects involving cephalopods became regulated by Directive 2010/63/EU, but at present there is little guidance specifically for cephalopods on a number of key requirements of the Directive, including: recognition of pain, suffering and distress and implementation of humane end-points; anaesthesia and analgesia, and humane killing. This paper critically reviews these key areas prior to the development of guidelines and makes recommendations, including identifying topics for further research. In particular: a) Evidence on how cephalopods might experience pain is reviewed; and a draft scheme of behavioural and physiological criteria for recognising and assessing pain, suffering and distress in cephalopods used in scientific procedures is presented and discussed. b) Agents and protocols currently used for general anaesthesia and analgesia are evaluated. Magnesium chloride, ethanol and clove oil are the most frequently used agents, but their efficacy and potential for induction of aversion need to be systematically investigated, according to the species of cephalopod and factors such as body weight, sex and water temperature. Means of sedating animals prior to anaesthesia should be investigated. Criteria for assessing depth of anaesthesia, including depression of ventilation, decrease in chromatophore tone (paling), reduced arm activity, tone and sucker adhesiveness, loss of normal posture and righting reflex, and loss of response to a noxious stimulus, are discussed. c) Analgesia should be provided for cephalopods used in scientific procedures, whenever this would be the case for vertebrates. However, research is needed to evaluate effective agents and administration routes for cephalopods. d) Techniques for local anaesthesia need to be defined and evaluated. e) Currently used methods of killing and criteria for confirmation of death in cephalopods are evaluated. Based on present knowledge, a protocol for humane killing of cephalopods is proposed. However, further evaluation is needed, along with development of humane methods of killing that will not compromise study of the brain. On humane grounds: i. mechanical (as opposed to chemical) methods of killing should not be used on conscious cephalopods (unless specifically authorised by the national competent authority); and ii. hatchlings and larvae should be killed by overdose of anaesthetic and not by immersion in tissue fixative.

Key gaps in current knowledge are also highlighted, so as to encourage research that will contribute to the evidence base needed to develop guidelines to the Directive.

Introduction

There are strong ethical, legal and scientific obligations to avoid, recognise, and alleviate any pain, suffering and distress caused to animals used in scientific procedures.

The ethical obligation is reflected in legal requirements to minimise suffering, such as those enshrined in EU Directive 2010/63/EU (European Parliament and Council of the European Union, 2010). This new law replaces EU Directive 86/609 and, for the first time, includes “all live cephalopods” within its scope (in addition to vertebrates).

The scientific imperative to reduce animal suffering arises because adverse effects such as pain and distress are likely to confound experimental results, especially if they are unrecognised. There are many studies showing that physiological responses to discomfort, pain, stress and distress can affect the quality of data obtained in studies involving vertebrates (e.g.: Hurst and West, 2010, Karelina et al., 2009, Roedel et al., 2006) and this is highly likely to be the case in cephalopod studies too.

Similar considerations apply when animals are humanely killed to obtain tissue for in vitro studies where suffering should be minimised on ethical, legal and also scientific grounds, as the physiological condition of the tissue may be affected by suffering around the time of killing.

A degree of suffering may be unavoidable in the experimental protocol (e.g. surgery, administration of substances or adverse reactions in toxicology procedures), or may itself be the object of the study, for example in some aspects of psychology or pain research. Whatever the cause, suffering should be recognised and assessed in order that it can be minimised at all times and so that pre-set “humane end points” can be implemented (see below).

This paper reviews some of the evidence on whether cephalopods experience suffering, proposes an objective approach for assessing suffering in an experimental setting, and reviews approaches to anaesthesia, analgesia and humane killing.

It should be emphasised that there is still much work to be done in all of the areas discussed in this paper. We anticipate that implementation of Directive 2010/63/EU will stimulate research to address some of the questions raised in relation to pain, suffering, distress, anaesthesia and euthanasia as well as questions discussed by Smith et al. (2013--this volume).

Section snippets

Evidence of the capacity for cephalopods to experience pain

A review of the published literature for evidence of nociceptors and for the perception of pain in cephalopods can be summarised as “absence of evidence rather than evidence of absence”. As pointed out by Smith et al. (2013--this volume), the time for debate about the rationale for including cephalopods within the scope of EU legislation on animal experiments has passed and the new law assumes that these animals can, and do, experience pain, suffering and distress. Nevertheless, there is a

Objective signs of pain, suffering and distress in cephalopods

Objective indicators that an animal could be experiencing pain, distress or other suffering are essential if appropriate action is to be taken to avoid, relieve and reduce suffering and to implement humane end-points (see below). Hawkins et al. (2011) provide practical guidance on defining and implementing welfare assessment schemes.

In the experience of many researchers, there are a number of behavioural and physiological signs that can indicate that ‘something is wrong’ with cephalopods. These

Humane endpoints in cephalopod studies

Directive 2010/63/EU requires that death as an end-point of a procedure should be avoided as far as possible and that humane end-points should be used to minimise the duration and intensity of animal suffering.

Humane end-points describe the circumstances in which a procedure will be stopped for animal welfare reasons, so as to limit the level of suffering experienced by the animal, regardless of whether further scientific results could be achieved (for details see Smith et al., 2013--this volume

General anaesthesia for cephalopods

The new EU Directive 2010/63/EU requires that anaesthesia must be used during scientific procedures, unless it is judged more traumatic than the procedure itself and/or is incompatible with the purpose of the procedure (Article 14).

It may be necessary to anaesthetise an animal for a number of reasons including:

  • i.

    performing a minor or major experimental surgical procedure, e.g. to lesion part of the nervous system surgically (e.g. Andrews and Tansey, 1983), chemically or electrolytically (e.g.

Local anaesthesia and analgesia for cephalopods

We have been unable to find any literature describing use of local anaesthetics or analgesics in cephalopods for procedures where such measures would be considered desirable if performed in a vertebrate. This is an area requiring investigation, particularly in view of the many types of surgical procedure with recovery (especially brain lesions) performed on cephalopods.

Methods for humane killing

There may be a requirement to humanely kill animals for a variety of reasons, e.g. at the termination of a study (if release to the wild or rehoming to a collection are not viable options); when a pre-set humane end point has been reached; if tissues or organs are required as part of a study; for veterinary reasons; or if animals are surplus to requirements and there is no alternative use for them.

Article 6 of Directive 2010/63/EU requires that, “Member States shall ensure that animals are

Acknowledgements

Some of the concepts discussed in this paper and in particular Table 1 emerged from a Cephalopod Working Group of the Boyd Group. We wish to thank colleagues from that group (G. Fiorito, J. Patterson, G. Ponte, J. Rundle, and R. Williamson) who are not authors on the current paper. PLRA wishes to thank ASSEMBLE (Association of European Marine Biological Laboratories) for funding a preliminary study of nociception in O. vulgaris at Stazione Zoologica Napoli during which some of the ideas in this

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    This article is part of a special issue on Cephalopod Biology published under the auspices of CephRes-ONLUS (www.cephalopodresearch.org).

    ☆☆

    All authors made an equivalent contribution to the manuscript.

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