1
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Bodnar MJ, Ratuski AS, Weary DM. Mouse isoflurane anesthesia using the drop method. Lab Anim 2023; 57:623-630. [PMID: 37144336 PMCID: PMC10693727 DOI: 10.1177/00236772231169550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 03/27/2023] [Indexed: 05/06/2023]
Abstract
Anesthesia with isoflurane prior to carbon dioxide euthanasia is recommended as a refinement, but vaporizer access can be limited. An alternative to vaporizers is the 'drop' method, introducing a fixed volume of isoflurane into the induction chamber. Previous work suggests that isoflurane administered at a concentration of 5% via the drop method is effective but aversive to mice; lower concentrations have not been tested. We assessed mouse behavior and insensibility with induction using the drop method for isoflurane concentrations below 5%. Male Crl:CD-1 (ICR) mice (n = 27) were randomly allocated to one of three isoflurane concentrations: 1.7%, 2.7%, and 3.7%. During induction, measures of insensibility and stress-related behaviors were recorded. All mice reached a surgical plane of anesthesia, and mice exposed to higher concentrations did so more quickly; as concentrations increased from 1.7 to 2.7 and 3.7%, the time to recumbency (Least squares means ± SE: 120.5 s ± 8.1, 97.9 s ± 8.1, and 82.8 s ± 8.1, respectively), loss of righting reflex (149.1 s ± 8.5, 127.7 s ± 8.5, and 100.7 s ± 8.5, respectively), and loss of pedal withdrawal reflex (214.5 s ± 8.3, 172.2 s ± 8.3, and 146.4 s ± 8.3, respectively) all declined. Rearing was the most frequently performed stress-related behavior, and was most pronounced immediately following isoflurane administration for all treatments. Our results indicate that the drop method can be used to effectively anesthetize mice with isoflurane concentrations as low as 1.7%; future work should assess mouse aversion.
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Affiliation(s)
- Maya J Bodnar
- UBC Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Canada
| | - Anna S Ratuski
- UBC Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Canada
| | - Daniel M Weary
- UBC Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Canada
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2
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Clarkson JM, Martin JE, Sparrey J, Leach MC, McKeegan DEF. Striving for humane deaths for laboratory mice: hypobaric hypoxia provides a potential alternative to carbon dioxide exposure. Proc Biol Sci 2023; 290:20222446. [PMID: 37122253 PMCID: PMC10130715 DOI: 10.1098/rspb.2022.2446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 03/29/2023] [Indexed: 05/02/2023] Open
Abstract
Killing is often an unavoidable and necessary procedure for laboratory mice involved in scientific research, and providing a humane death is vital for public acceptance. Exposure to carbon dioxide (CO2) gas is the most widely used methodology despite well proven welfare concerns. Consequently, the continued use of CO2 and its globally permitted status in legislation and guidelines presents an ethical dilemma for users. We investigated whether killing with hypobaric hypoxia via gradual decompression was associated with better welfare outcomes for killing laboratory mice. We compared the spontaneous behaviour of mice exposed to CO2, decompression or sham conditions, and used analgesic or anxiolytic interventions to determine their relative welfare impact. Gradual decompression resulted in longer times to unconsciousness and death and the pharmacological interventions support the notion of a minimally negative animal experience, while providing further evidence for pain and anxiety associated with exposure to CO2. Decompression resulted in moderate ear haemorrhage, but our welfare assessment suggests this may happen when mice are unconscious. Hence, gradual decompression could be the basis of significant refinement for killing laboratory mice. Future work should corroborate behaviour with neurobiological markers of loss of consciousness to verify the conscious phase of concern for animal welfare.
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Affiliation(s)
- J. M. Clarkson
- School of Biodiversity, One Health and Veterinary Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- School for Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - J. E. Martin
- School for Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - J. Sparrey
- Livetec Systems Ltd, Wrest Park, Silsoe, Bedford, UK
| | - M. C. Leach
- Comparative Biology Centre, Newcastle University, Newcastle upon Tyne, UK
| | - D. E. F. McKeegan
- School of Biodiversity, One Health and Veterinary Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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3
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McKinney MM, Dupont WD, Corson KJ, Wallace JM, Jones CP. Physiologic and Behavioral Effects in Mice Anesthetized with Isoflurane in a Red-tinted or a Traditional Translucent Chamber. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2022; 61:322-332. [PMID: 35840316 PMCID: PMC9674017 DOI: 10.30802/aalas-jaalas-22-000011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Isoflurane has been characterized as a distressing agent for rodents, causing both physiologic and behavioral effects. Using a "darkened home cage" has been recommended during CO₂ administration for rodent euthanasia; this is arguably a similar animal experience to anesthetic induction with isoflurane. Based on the premise that rodents perceive red light as darkness via the primary optic tract, we compared physiologic and behavioral markers of stress in 2 inbred strains of mice (C57BL/6J and BALB/cJ) anesthetized with isoflurane in either a red-tinted (dark) induction chamber or a traditional translucent induction chamber. Physiologic stress was assessed based on plasma levels of norepinephrine, epinephrine, and corticosterone. Stress-related behaviors (rearing, face wiping, and jumping) were recorded on video and scored from initiation of induction to loss of consciousness. No significant correlations were found between chamber type and physiologic stress hormones. As compared with the translucent chamber, stress-related behaviors were more frequent in the red-tinted chamber, including: 1) significantly higher rearing frequencies in BALB/cJ mice; 2) higher behavioral stress scores in BALB/cJ and male C57BL/6J mice; and 3) more face wiping behavior when considering all mice combined. These findings suggest that mice do not experience significant alleviation of physiologic indices of stress when anesthetized in a red-tinted induction chamber. Furthermore, isoflurane induction in the red-tinted chamber appeared to increase the expression of stress-related behaviors, particularly in BALB/cJ mice. Based on our findings and a growing body of literature on the unintended effects of red light, we do not recommend using red-tinted chambers for induction of anesthesia in mice.
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Affiliation(s)
- Michael M McKinney
- Department of Pathology, Immunology, and
Microbiology,,Divison of Animal Care, and,Corresponding author.
| | - William D Dupont
- Department of Biostatistics, Vanderbilt University
Medical Center, Nashville, Tennessee
| | | | - Jeanne M Wallace
- Department of Pathology, Immunology, and
Microbiology,,Divison of Animal Care, and
| | - Carissa P Jones
- Department of Pathology, Immunology, and
Microbiology,,Divison of Animal Care, and
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4
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Clarkson JM, Martin JE, McKeegan DEF. A review of methods used to kill laboratory rodents: issues and opportunities. Lab Anim 2022; 56:419-436. [PMID: 35611553 DOI: 10.1177/00236772221097472] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Rodents are the most widely used species for scientific purposes. A critical pre-requisite of their use, based on utilitarian ethical reasoning, is the provision of a humane death when necessary for scientific or welfare grounds. Focussing on the welfare challenges presented by current methods, we critically evaluate the literature, consider emerging methodologies that may have potential for refinement and highlight knowledge gaps for future research. The evidence supports the conclusion that scientists and laboratory personnel should seek to avoid killing laboratory rodents by exposing them to carbon dioxide (CO2), unless exploiting its high-throughput advantage. We suggest that stakeholders and policymakers should advocate for the removal of CO2 from existing guidelines, instead making its use conditionally acceptable with justification for additional rationale for its application. With regards to physical methods such as cervical dislocation, decapitation and concussion, major welfare concerns are based on potential inaccuracy in application and their susceptibility to high failure rates. There is a need for independent quality-controlled training programmes to facilitate optimal success rates and the development of specialist tools to improve outcomes and reliability. Furthermore, we highlight questions surrounding the inconsistent inclusion criteria and acceptability of physical methods in international regulation and/or guidance, demonstrating a lack of cohesion across countries and lack of a comprehensive 'gold standard' methodology. We encourage better review of new data and championing of open access scientific resources to advocate for best practice and enable significant changes to policy and legislation to improve the welfare of laboratory rodents at killing.
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Affiliation(s)
- Jasmine M Clarkson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, UK
| | - Jessica E Martin
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, UK
| | - Dorothy E F McKeegan
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, UK
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5
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Clarkson JM, McKeegan DEF, Sparrey J, Marchesi F, Leach MC, Martin JE. Determining Candidate Hypobaric Hypoxia Profiles for Humane Killing of Laboratory Mice. Front Vet Sci 2022; 9:834478. [PMID: 35400097 PMCID: PMC8988232 DOI: 10.3389/fvets.2022.834478] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/17/2022] [Indexed: 01/28/2023] Open
Abstract
Millions of mice are used annually in scientific research and must be humanely killed. Despite significant welfare concerns, carbon dioxide exposure remains the most common killing method, primarily because there is no practical and humane alternative. We explored whether hypobaric hypoxia via gradual decompression could induce a non-recovery state in anesthetized male C57BL/6 and Balb/c laboratory mice. We aimed to determine if this was possible in a feasible timescale with minimal pathological consequences, as a proof-of-principle step. Systematic evaluation of two decompression rates (75, 150 ms−1) and three profile shapes (accelerated, linear, gradual) in a factorial design revealed that hypobaric hypoxia effectively induced a non-recovery state in anesthetized laboratory mice, irrespective of decompression rate and shape. Mice took longer to reach a non-recovery state with the 75 ms−1 decompression rate (75 ms−1: 257 ± 8.96 vs. 150 ms−1: 214 ± 7.26 s), with longer latencies in gradual and linear shaped profiles. Accelerated shaped profiles were least susceptible to meaningful refinement via rate. The only pathological changes of concern were moderate middle ear congestion and hemorrhage. These findings suggest that hypobaric hypoxia has potential, and subsequent work will evaluate the welfare consequences of gradual decompression in conscious mice, to identify decompression profiles that minimize welfare harms associated with ear barotrauma.
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Affiliation(s)
- Jasmine M. Clarkson
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- *Correspondence: Jasmine M. Clarkson
| | - Dorothy E. F. McKeegan
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | | | - Francesco Marchesi
- School of Veterinary Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Matthew C. Leach
- School for Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jessica E. Martin
- The Royal (Dick) School of Veterinary Studies, The Roslin Institute, The University of Edinburgh, Edinburgh, United Kingdom
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6
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Validation of a combined approach-avoidance and conditioned stimulus aversion paradigm for evaluating aversion in chickens. PLoS One 2021; 16:e0247674. [PMID: 33630948 PMCID: PMC7906348 DOI: 10.1371/journal.pone.0247674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 02/11/2021] [Indexed: 11/19/2022] Open
Abstract
Understanding animals’ aversion is important to improving their welfare. Aversion is often assessed using an approach-avoidance (AA) test in which animals have to forfeit a reward if they want to avoid an event or environment presented in the same place. However, sometimes the event/environment suspected to be aversive may physically impair the animal’s ability to withdraw from that place (i.e. its ability to express aversion), leading to incorrect interpretations. Combining AA with a Conditioned-Stimulus that predicts the event/environment may overcome this problem by allowing animals to demonstrate aversion without exposure to the stimulus. We aimed to validate this paradigm for testing aversion in chickens. Seven Hyline-Brown chickens were trained to obtain a food reward from a coloured bowl located in the test chamber (TC) of a two-chambered box; the reward was presented in a green bowl with an inactivated air canister or a red bowl with the canister activated to deliver an air puff. Two 5-minute tests were conducted, one with each bowl colour and both with the canister inactivated. All chickens entered TC with the green bowl. With the red bowl, two chickens entered on their first attempt, one fully entered after a partial entry (3/7 fully entered), two made only partial entries and two made no attempts to enter. Chickens spent less time in the TC with the red bowl (median 31s, IQR 7–252) compared to the green bowl (293s, IQR 290–294; p = 0.008). The higher ratio of partial to full entries, failure to enter the TC and less time spent in TC reflected chickens’ aversion to the air puff, signalled by the red bowl. The paradigm allowed chickens to demonstrate aversion without exposure to the aversive stimulus during testing.
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7
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Steiner AR, Rousseau-Blass F, Schroeter A, Hartnack S, Bettschart-Wolfensberger R. Systematic Review: Anesthetic Protocols and Management as Confounders in Rodent Blood Oxygen Level Dependent Functional Magnetic Resonance Imaging (BOLD fMRI)-Part B: Effects of Anesthetic Agents, Doses and Timing. Animals (Basel) 2021; 11:ani11010199. [PMID: 33467584 PMCID: PMC7830239 DOI: 10.3390/ani11010199] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/17/2020] [Accepted: 12/29/2020] [Indexed: 02/07/2023] Open
Abstract
Simple Summary To understand brain function in rats and mice functional magnetic resonance imaging of the brain is used. With this type of “brain scan” regional changes in blood flow and oxygen consumption are measured as an indirect surrogate for activity of brain regions. Animals are often anesthetized for the experiments to prevent stress and blurred images due to movement. However, anesthesia may alter the measurements, as blood flow within the brain is differently affected by different anesthetics, and anesthetics also directly affect brain function. Consequently, results obtained under one anesthetic protocol may not be comparable with those obtained under another, and/or not representative for awake animals and humans. We have systematically searched the existing literature for studies analyzing the effects of different anesthesia methods or studies that compared anesthetized and awake animals. Most studies reported that anesthetic agents, doses and timing had an effect on functional magnetic resonance imaging results. To obtain results which promote our understanding of brain function, it is therefore essential that a standard for anesthetic protocols for functional magnetic resonance is defined and their impact is well characterized. Abstract In rodent models the use of functional magnetic resonance imaging (fMRI) under anesthesia is common. The anesthetic protocol might influence fMRI readouts either directly or via changes in physiological parameters. As long as those factors cannot be objectively quantified, the scientific validity of fMRI in rodents is impaired. In the present systematic review, literature analyzing in rats and mice the influence of anesthesia regimes and concurrent physiological functions on blood oxygen level dependent (BOLD) fMRI results was investigated. Studies from four databases that were searched were selected following pre-defined criteria. Two separate articles publish the results; the herewith presented article includes the analyses of 83 studies. Most studies found differences in BOLD fMRI readouts with different anesthesia drugs and dose rates, time points of imaging or when awake status was compared to anesthetized animals. To obtain scientifically valid, reproducible results from rodent fMRI studies, stable levels of anesthesia with agents suitable for the model under investigation as well as known and objectively quantifiable effects on readouts are, thus, mandatory. Further studies should establish dose ranges for standardized anesthetic protocols and determine time windows for imaging during which influence of anesthesia on readout is objectively quantifiable.
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Affiliation(s)
- Aline R. Steiner
- Section of Anaesthesiology, Department of Clinical and Diagnostic Services, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland;
- Correspondence:
| | - Frédérik Rousseau-Blass
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada;
| | - Aileen Schroeter
- Institute for Biomedical Engineering, University and ETH Zurich, 8093 Zurich, Switzerland;
| | - Sonja Hartnack
- Section of Epidemiology, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland;
| | - Regula Bettschart-Wolfensberger
- Section of Anaesthesiology, Department of Clinical and Diagnostic Services, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland;
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8
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Turner PV, Hickman DL, van Luijk J, Ritskes-Hoitinga M, Sargeant JM, Kurosawa TM, Agui T, Baumans V, Choi WS, Choi YK, Flecknell PA, Lee BH, Otaegui PJ, Pritchett-Corning KR, Shimada K. Welfare Impact of Carbon Dioxide Euthanasia on Laboratory Mice and Rats: A Systematic Review. Front Vet Sci 2020; 7:411. [PMID: 32793645 PMCID: PMC7387666 DOI: 10.3389/fvets.2020.00411] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/09/2020] [Indexed: 12/27/2022] Open
Abstract
Background: There has been increased concern about the suitability of CO2 as a method for euthanasia of laboratory mice and rats, including the potential discomfort, pain or distress that animals may experience prior to loss of consciousness; time to loss of consciousness; best methods for use of CO2; and the availability of better alternatives. These discussions have been useful in providing new information, but have resulted in significant confusion regarding the acceptability of CO2 for rodent euthanasia. In some cases, researchers and veterinarians have become uncertain as to which techniques to recommend or use for euthanasia of laboratory mice and rats. Methods: The International Association of Colleges of Laboratory Animal Medicine (IACLAM) convened a taskforce to examine the evidence for adverse welfare indicators in laboratory rats and mice undergoing CO2 euthanasia using a SYRCLE-registered systematic review protocol. Of 3,772 papers identified through a database search (PubMed, Web of Science, CAB Direct, Agricola, and grey literature) from 1900 to 2017, 37 studies were identified for detailed review (some including more than one species or age group), including 15 in adult mice, 21 in adult rats, and 5 in neonates of both species. Experiments or reports were excluded if they only assessed parameters other than those directly affecting animal welfare during CO2 induction and/or euthanasia. Results: Study design and outcome measures were highly variable and there was an unclear to high risk of bias in many of the published studies. Changes in the outcome measures evaluated were inconsistent or poorly differentiated. It is likely that repeated exposures to carbon dioxide inhalation are aversive to adult rats and mice, based on avoidance behavior studies; however, this effect is largely indistinguishable from aversion induced by repeated exposures to other inhalant anesthetic gasses. Conclusion: There is insufficient evidence to permit an unbiased assessment of the effect of CO2 inhalation during euthanasia on welfare indicators in laboratory mice and rats. Additional well-designed, unbiased, and adequately powered studies are needed to accurately assess the welfare of laboratory mice and rats undergoing euthanasia via CO2 gas.
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Affiliation(s)
- Patricia V. Turner
- Department of Pathobiology, University of Guelph, Guelph, ON, Canada
- Global Animal Welfare and Training, Charles River, Wilmington, MA, United States
| | - Debra L. Hickman
- Laboratory Animal Resource Center, School of Medicine, Indiana University, Indianapolis, IN, United States
| | - Judith van Luijk
- Department of Health Evidence, SYstematic Review Center for Laboratory Experimentation (SYRCLE), Radboud University, Nijmegen, Netherlands
| | - Merel Ritskes-Hoitinga
- Department of Health Evidence, SYstematic Review Center for Laboratory Experimentation (SYRCLE), Radboud University, Nijmegen, Netherlands
| | - Jan M. Sargeant
- Department of Population Medicine, University of Guelph, Guelph, ON, Canada
- Centre for Public Health and Zoonoses, University of Guelph, Guelph, ON, Canada
| | - T. Miki Kurosawa
- Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
| | - Takashi Agui
- Department of Applied Veterinary Science, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Vera Baumans
- Department of Animals, Science and Society, Utrecht University, Utrecht, Netherlands
| | - Woo Sung Choi
- National New Drug Development Cluster, Woojung Bio, Suwon-si, South Korea
| | - Yang-Kyu Choi
- Department of Laboratory Animal Medicine, College of Veterinary Medicine, Konkuk University, Seoul, South Korea
| | - Paul A. Flecknell
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Byeong H. Lee
- Osong Medical Innovation Foundation, Cheongju, South Korea
| | - Pedro J. Otaegui
- Laboratory Animal Facilities, Autonomous University of Barcelona, Barcelona, Spain
| | - Kathleen R. Pritchett-Corning
- Office of Animal Resources, Harvard University Faculty of Arts and Sciences, Cambridge, MA, United States
- Department of Comparative Medicine, University of Washington, Seattle, WA, United States
| | - Keisuke Shimada
- Animal Resource Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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9
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Frost K, Shah M, Leung VS, Pang DS. Aversion to Desflurane and Isoflurane in Sprague-Dawley Rats ( Rattus Norvegicus). Animals (Basel) 2020; 10:ani10060950. [PMID: 32486178 PMCID: PMC7341512 DOI: 10.3390/ani10060950] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/07/2020] [Accepted: 05/26/2020] [Indexed: 11/29/2022] Open
Abstract
Simple Summary Euthanasia is one of the most commonly performed procedures in laboratory rodents, as the majority of animals are killed upon project completion or when humane endpoints have been reached. Overdose with carbon dioxide gas remains a widely used killing method, despite evidence it is aversive to rodents. The inhalant anesthetic isoflurane is a refinement to overdose with carbon dioxide, but also elicits aversion in rodents. The inhalant anesthetic desflurane has a faster onset of action than isoflurane and may therefore offer further refinement. In this study, rat aversion to desflurane and isoflurane was compared. Isoflurane and desflurane were similarly aversive; however, desflurane exposure resulted in a shorter time to achieve recumbency, shortening any period of potential distress. Therefore, desflurane represents a refinement over the use of isoflurane. Abstract Carbon dioxide and isoflurane are widely used for killing rats, yet may not truly achieve “euthanasia”, because they elicit aversion. The inhalant anesthetic desflurane is faster acting than isoflurane, representing a potential refinement. Using an aversion-avoidance paradigm, 24 rats were exposed to isoflurane or desflurane (n = 12 per group) at initial exposure. Fourteen rats were then re-exposed to isoflurane or desflurane (n = 7 per group), after a 7 days washout period. Initial exposure: time to recumbency was faster for desflurane than isoflurane (p = 0.0008, 95% CI [-12.9 to 32.6 s]), with 9/12 and 6/12 rats becoming recumbent, respectively. At initial exposure, there was no difference between groups in time to withdrawal (p = 0.714). At re-exposure, all rats withdrew and no rats became recumbent. Time to withdrawal at re-exposure did not differ between treatment groups (p = 0.083). Compared to initial exposure, time to withdrawal during re-exposure was similar for isoflurane (p = 0.228) and faster with desflurane (p = 0.012, 95% CI [19.1 to 49.5 s]). Isoflurane and desflurane are similarly aversive, with aversion increasing at re-exposure. The shorter time from exposure to recumbency with desflurane indicates that any distress is of a shorter duration when compared with isoflurane.
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Affiliation(s)
- Katrina Frost
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada;
| | - Maaria Shah
- Faculty of Science, University of Calgary, Calgary, AB T2N 1N4, Canada;
| | - Vivian S.Y. Leung
- Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada;
| | - Daniel S.J. Pang
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada;
- Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada;
- Correspondence:
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10
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Andresen N, Wöllhaf M, Hohlbaum K, Lewejohann L, Hellwich O, Thöne-Reineke C, Belik V. Towards a fully automated surveillance of well-being status in laboratory mice using deep learning: Starting with facial expression analysis. PLoS One 2020; 15:e0228059. [PMID: 32294094 PMCID: PMC7159220 DOI: 10.1371/journal.pone.0228059] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 01/06/2020] [Indexed: 01/09/2023] Open
Abstract
Assessing the well-being of an animal is hindered by the limitations of efficient communication between humans and animals. Instead of direct communication, a variety of parameters are employed to evaluate the well-being of an animal. Especially in the field of biomedical research, scientifically sound tools to assess pain, suffering, and distress for experimental animals are highly demanded due to ethical and legal reasons. For mice, the most commonly used laboratory animals, a valuable tool is the Mouse Grimace Scale (MGS), a coding system for facial expressions of pain in mice. We aim to develop a fully automated system for the surveillance of post-surgical and post-anesthetic effects in mice. Our work introduces a semi-automated pipeline as a first step towards this goal. A new data set of images of black-furred laboratory mice that were moving freely is used and provided. Images were obtained after anesthesia (with isoflurane or ketamine/xylazine combination) and surgery (castration). We deploy two pre-trained state of the art deep convolutional neural network (CNN) architectures (ResNet50 and InceptionV3) and compare to a third CNN architecture without pre-training. Depending on the particular treatment, we achieve an accuracy of up to 99% for the recognition of the absence or presence of post-surgical and/or post-anesthetic effects on the facial expression.
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Affiliation(s)
- Niek Andresen
- Department of Computer Vision & Remote Sensing, Technische Universität Berlin, Berlin, Germany
| | - Manuel Wöllhaf
- Department of Computer Vision & Remote Sensing, Technische Universität Berlin, Berlin, Germany
| | - Katharina Hohlbaum
- Institute of Animal Welfare, Animal Behavior, and Laboratory Animal Science, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- * E-mail: (KH); (VB)
| | - Lars Lewejohann
- Institute of Animal Welfare, Animal Behavior, and Laboratory Animal Science, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- German Centre for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Olaf Hellwich
- Department of Computer Vision & Remote Sensing, Technische Universität Berlin, Berlin, Germany
| | - Christa Thöne-Reineke
- Institute of Animal Welfare, Animal Behavior, and Laboratory Animal Science, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Vitaly Belik
- System Modeling Group, Institute for Veterinary Epidemiology and Biostatistics, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- * E-mail: (KH); (VB)
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11
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Taylor K, Alvarez LR. An Estimate of the Number of Animals Used for Scientific Purposes Worldwide in 2015. Altern Lab Anim 2020; 47:196-213. [DOI: 10.1177/0261192919899853] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Few attempts have been made to estimate the global use of animals in experiments, since our own estimated figure of 115.2 million animals for the year 2005. Here, we provide an update for the year 2015. Data from 37 countries that publish national statistics were standardised against the definitions of ‘animals’ and ‘procedures’ used in the European Union (EU) Directive 2010/63/EU. We also applied a prediction model, based on publication rates, to estimate animal use in a further 142 countries. This yielded an overall estimate of global animal use in scientific procedures of 79.9 million animals, a 36.9% increase on the equivalent estimated figure for 2005, of 58.3 million animals. We further extrapolated this estimate to obtain a more comprehensive final global figure for the number of animals used for scientific purposes in 2015, of 192.1 million. This figure included animals killed for their tissues, normal and genetically modified (GM) animals without a harmful genetic mutation that are used to maintain GM strains and animals bred for laboratory use but not used. Since the 2005 study, there has been no evident increase in the number of countries publishing data on the numbers of animals used in experiments. Without regular, accurate statistics, the impact of efforts to replace, reduce and refine animal experiments cannot be effectively monitored.
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Affiliation(s)
- Katy Taylor
- Cruelty Free International Trust, London, UK
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12
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Suckow MA, Gimpel JL. Approaches to the humane euthanasia of research animals. Anim Biotechnol 2020. [DOI: 10.1016/b978-0-12-811710-1.00037-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Steiner AR, Flammer SA, Beausoleil NJ, Berg C, Bettschart-Wolfensberger R, Pinillos RG, Golledge HDW, Marahrens M, Meyer R, Schnitzer T, Toscano MJ, Turner PV, Weary DM, Gent TC. Humanely Ending the Life of Animals: Research Priorities to Identify Alternatives to Carbon Dioxide. Animals (Basel) 2019; 9:E911. [PMID: 31684044 PMCID: PMC6912382 DOI: 10.3390/ani9110911] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/14/2019] [Accepted: 10/25/2019] [Indexed: 02/06/2023] Open
Abstract
: The use of carbon dioxide (CO2) for stunning and killing animals is considered to compromise welfare due to air hunger, anxiety, fear, and pain. Despite decades of research, no alternatives have so far been found that provide a safe and reliable way to induce unconsciousness in groups of animals, and also cause less distress than CO2. Here, we revisit the current and historical literature to identify key research questions that may lead to the identification and implementation of more humane alternatives to induce unconsciousness in mice, rats, poultry, and pigs. In addition to the evaluation of novel methods and agents, we identify the need to standardise the terminology and behavioural assays within the field. We further reason that more accurate measurements of consciousness state are needed and serve as a central component in the assessment of suffering. Therefore, we propose a roadmap toward improving animal welfare during end-of-life procedures.
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Affiliation(s)
- Aline R Steiner
- Department of Clinical and Diagnostic Services, Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, 8057 Zurich, Switzerland.
| | - Shannon Axiak Flammer
- Department of Clinical Veterinary Medicine, Section of Anesthesia and Analgesia, Vetsuisse Faculty, University of Berne, Laenggassstrasse 124, 3012 Bern, Switzerland.
| | - Ngaio J Beausoleil
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Palmerston North 4410, New Zealand.
| | - Charlotte Berg
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Box 234, SE-53223 Skara, Sweden.
| | - Regula Bettschart-Wolfensberger
- Department of Clinical and Diagnostic Services, Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, 8057 Zurich, Switzerland.
| | - Rebeca García Pinillos
- Animal and Plant Health Agency and Department for Environment, Food and Rural Affairs, Nobel House, 17 Smith Square, London SW1P 3JR, UK.
| | - Huw D W Golledge
- Universities Federation for Animal Welfare (UFAW), The Old School, Brewhouse Hill, Wheathampstead, Hertfordshire AL4 8AN, UK.
| | - Michael Marahrens
- Institute of Animal Welfare and Animal Husbandry, Friedrich-Loeffler-Institut, Dörnbergstraße 25/27, 29223 Celle, Germany.
| | - Robert Meyer
- Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
| | - Tobias Schnitzer
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacherstrasse 124, 4070 Basel, Switzerland.
| | - Michael J Toscano
- Center for Proper Housing: Poultry and Rabbits (ZTHZ), Animal Welfare Division, VPH Institute, University of Bern, 3052 Zollikofen, Switzerland.
| | - Patricia V Turner
- Department of Pathobiology, University of Guelph, Guelph, ON, N1G 2W1, Canada and Charles River, Wilmington, MA 01887, USA.
| | - Daniel M Weary
- Animal Welfare Program, University of British Colombia, 2357 Main Mall, Vancouver, BC V6T 1Z4, Canada.
| | - Thomas C Gent
- Department of Clinical and Diagnostic Services, Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, 8057 Zurich, Switzerland.
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14
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Alternatives to Carbon Dioxide-Taking Responsibility for Humanely Ending the Life of Animals. Animals (Basel) 2019; 9:ani9080482. [PMID: 31344949 PMCID: PMC6720529 DOI: 10.3390/ani9080482] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/16/2019] [Accepted: 07/19/2019] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Carbon dioxide has long been considered one of the better methods for euthanizing laboratory rodents because it allows termination of several animals at one time, does not require handling of the animal, is easy to use, is inexpensive, and is environmentally friendly. Research, though, has shown that this gas is aversive to rodents and that it may be inhumane to expose them to this gas while they are conscious. Therefore, the Swiss Federal Food Safety and Veterinary Office has set out to find a suitable replacement and organized a meeting that included representatives and experts of the different stakeholders involved in this process in order to find a solution. The conclusion of this meeting was that a replacement is required, and the next step would be to draft a research strategy to find a suitable replacement. Abstract Carbon dioxide (CO2) is commonly used to kill rodents. However, a large body of research has now established that CO2 is aversive to them. A multidisciplinary symposium organized by the Swiss Federal Food Safety and Veterinary Office discussed the drawbacks and alternatives to CO2 in euthanasia protocols for laboratory animals. Dialogue was facilitated by brainstorming sessions in small groups and a “World Café”. A conclusion from this process was that alternatives to CO2 were urgently required, including a program of research and extension to meet the needs for humane killing of these animals. The next step will involve gathering a group of international experts to formulate, draft, and publish a research strategy on alternatives to CO2.
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15
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Gjendal K, Ottesen JL, Olsson IAS, Sørensen DB. Burrowing and nest building activity in mice after exposure to grid floor, isoflurane or ip injections. Physiol Behav 2019; 206:59-66. [DOI: 10.1016/j.physbeh.2019.02.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/22/2019] [Accepted: 02/16/2019] [Indexed: 01/23/2023]
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16
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Gent TC, Vyssotski AL, Detotto C, Isler S, Wehrle M, Bettschart-Wolfensberger R. Is xenon a suitable euthanasia agent for mice? Vet Anaesth Analg 2019; 46:652-657. [PMID: 31151872 DOI: 10.1016/j.vaa.2019.04.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 03/28/2019] [Accepted: 04/03/2019] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To compare behavioural and electrophysiological variables of mice undergoing gas euthanasia with either xenon (Xe) or carbon dioxide (CO2). STUDY DESIGN Single animals chronically instrumented for electroencephalography (EEG) recording were randomized to undergo euthanasia with either CO2 or Xe (n = 6 animals per group). ANIMALS Twelve adult (>6 weeks old) male C57Bl6/n mice. METHODS Mice were surgically instrumented with EEG and electromyogram electrodes. Following a 7-day recovery period, animals were placed individually in a sealed chamber and a 5-minute baseline recorded in 21% O2. Gas [100% Xe (n = 6) or 100% CO2 (n = 6)] was then added to the chamber at 30% chamber volume minute-1 (2.8 L minute-1) until cessation of breathing. EEG, behaviour (jumping and freezing) and locomotion speed were recorded throughout. RESULTS Mice undergoing single gas euthanasia with Xe did not show jumping or freezing behaviours and had reduced locomotion speed compared to baseline, in contrast to CO2, which resulted in increases in these variables. EEG recordings revealed sedative effects from Xe but heightened arousal from CO2. CONCLUSIONS Our data suggest that Xe may be less aversive than CO2 when using a 30% chamber volume minute-1 fill rate and could improve the welfare of mice undergoing gas euthanasia.
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Affiliation(s)
- Thomas C Gent
- Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
| | - Alexei L Vyssotski
- Institute for Neuroinformatics, University of Zürich and ETH Zurich, Zurich, Switzerland
| | - Carlotta Detotto
- Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Sarah Isler
- Natur- und Tierpark Goldau, Goldau, Switzerland
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17
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Jensen TL, Kiersgaard MK, Mikkelsen LF, Sørensen DB. Fasting of male mice - Effects of time point of initiation and duration on clinical chemistry parameters and animal welfare. Lab Anim 2019; 53:587-597. [PMID: 30741083 DOI: 10.1177/0023677218824373] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Fasting of mice is a common procedure, which can affect the outcome of the study as well as animal welfare. In this study, we assess the effects of fasting, fasting duration and fasting initiation time in relation to light schedule and present suggestions for optimization of fasting. Male C57BL/6NCrl mice were fasted for 0, 3, 6, 12, 18 and 24 hours initiated either in the light period (photophase) or the dark period (scotophase). Body weight, gastric content, body temperature, corticosterone and 19 routine clinical chemistry parameters were evaluated. Fasting caused significant changes in most of the measured parameters. Increasing duration of fasting resulted in increasing physiological changes. Fasting initiated in the scotophase caused more significant changes than fasting initiated in the photophase. To cause the least physiological changes in mice and increase animal welfare, mice should preferably be fasted in the photophase and for the shortest possible period allowed by the experimental purpose of fasting.
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Affiliation(s)
| | | | | | - Dorte B Sørensen
- Section of Experimental Animal Models, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Kbh N, Denmark
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18
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Detotto C, Isler S, Wehrle M, Vyssotski AL, Bettschart-Wolfensberger R, Gent TC. Nitrogen gas produces less behavioural and neurophysiological excitation than carbon dioxide in mice undergoing euthanasia. PLoS One 2019; 14:e0210818. [PMID: 30703117 PMCID: PMC6354991 DOI: 10.1371/journal.pone.0210818] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 01/02/2019] [Indexed: 12/04/2022] Open
Abstract
Carbon dioxide (CO2) is one of the most commonly used gas euthanasia agents in mice, despite reports of aversion and nociception. Inert gases such as nitrogen (N2) may be a viable alternative to carbon dioxide. Here we compared behavioural and electrophysiological reactions to CO2 or N2 at either slow fill or rapid fill in C57Bl/6 mice undergoing gas euthanasia. We found that mice euthanised with CO2 increased locomotor activity compared to baseline, whereas mice exposed to N2 decreased locomotion. Furthermore, mice exposed to CO2 showed significantly more vertical jumps and freezing episodes than mice exposed to N2. We further found that CO2 exposure resulted in increased theta:delta of the EEG, a measure of excitation, whereas the N2 decreased theta:delta. Differences in responses were not oxygen-concentration dependent. Taken together, these results demonstrate that CO2 increases both behavioural and electrophysiological excitation as well as producing a fear response, whereas N2 reduces behavioural activity and central neurological depression and may be less aversive although still produces a fear response. Further studies are required to evaluate N2 as a suitable euthanasia agent for mice.
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Affiliation(s)
- Carlotta Detotto
- Section of Anaesthesiology, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland
| | - Sarah Isler
- Natur- und Tierpark Goldau, Goldau, Switzerland
| | | | | | | | - Thomas C. Gent
- Section of Anaesthesiology, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland
- * E-mail:
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19
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Herrmann K, Flecknell P. The Application of Humane Endpoints and Humane Killing Methods in Animal Research Proposals: A Retrospective Review. Altern Lab Anim 2018; 46:317-333. [DOI: 10.1177/026119291804600606] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Refinement refers to the use of methods that help to minimise animal suffering in the laboratory. Research in this area has increased significantly over the past two decades. However, the extent to which refinements are applied in practice is uncertain. To provide an indication of the implementation and awareness of refinements, we reviewed the experimental techniques for 684 surgical interventions described in 506 animal research applications sent to the German competent authorities for approval in 2010. In this paper, we describe and discuss the appropriateness of the proposed humane endpoints and killing methods. We found that, when the investigators included humane endpoints in their application, these were often lacking in detail and/or were to be implemented at a late stage of suffering. In addition, the choice of method to kill the animals could be improved in the majority of the applications. We provide recommendations for future improvements, based on the recent literature. To ensure scientific rigour, avoid needless animal suffering and enable an accurate harm–benefit analysis, animal researchers have to be knowledgeable about refinement methods and apply them effectively. To assess compliance and ensure that only those studies in which potential benefits outweigh the harms are carried out, reviews such as ours — as well as retrospective assessments of actual harms and benefits — should be conducted widely and regularly, and the findings should be published.
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Affiliation(s)
- Kathrin Herrmann
- Freie Universität Berlin, Department of Veterinary Medicine, Institute of Pharmacology and Toxicology, Berlin, Germany
| | - Paul Flecknell
- Newcastle University, The Medical School, Comparative Biology Centre, Newcastle upon Tyne, UK
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20
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Does the Stress of Laboratory Life and Experimentation on Animals Adversely Affect Research Data? A Critical Review. Altern Lab Anim 2018; 46:291-305. [DOI: 10.1177/026119291804600501] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recurrent acute and/or chronic stress can affect all vertebrate species, and can have serious consequences. It is increasingly and widely appreciated that laboratory animals experience significant and repeated stress, which is unavoidable and is caused by many aspects of laboratory life, such as captivity, transport, noise, handling, restraint and other procedures, as well as the experimental procedures applied to them. Such stress is difficult to mitigate, and lack of significant desensitisation/habituation can result in considerable psychological and physiological welfare problems, which are mediated by the activation of various neuroendocrine networks that have numerous and pervasive effects. Psychological damage can be reflected in stereotypical behaviours, including repetitive pacing and circling, and even self-harm. Physical consequences include adverse effects on immune function, inflammatory responses, metabolism, and disease susceptibility and progression. Further, some of these effects are epigenetic, and are therefore potentially transgenerational: the biology of animals whose parents/grandparents were wild-caught and/or have experienced chronic stress in laboratories could be altered, as compared to free-living individuals. It is argued that these effects must have consequences for the reliability of experimental data and their extrapolation to humans, and this may not be recognised sufficiently among those who use animals in experiments.
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21
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Marquardt N, Feja M, Hünigen H, Plendl J, Menken L, Fink H, Bert B. Euthanasia of laboratory mice: Are isoflurane and sevoflurane real alternatives to carbon dioxide? PLoS One 2018; 13:e0203793. [PMID: 30199551 PMCID: PMC6130864 DOI: 10.1371/journal.pone.0203793] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 08/28/2018] [Indexed: 01/17/2023] Open
Abstract
In the European Union (EU) millions of laboratory mice are used and killed for experimental and other scientific purposes each year. Although controversially discussed, the use of carbon dioxide (CO2) is still permitted for killing rodents according to the Directive 2010/63/EU. Within the scope of refinement, our aim was to investigate if isoflurane and sevoflurane are an appropriate alternative killing method to CO2 in mice. Different concentrations of CO2 (filling rates of 20%, 60%, 100%; CO2 20, 60, 100), isoflurane (Iso 2%, 5%) and sevoflurane (Sevo 4.8%, 8%) were compared in two mouse strains (NMRI, C57Bl/6J) using a broad spectrum of behavioral parameters, including the approach-avoidance test, and analyzing blood for stress parameters (glucose, adrenaline, noradrenaline). We focused in our study on the period from the beginning of the gas inlet to loss of consciousness, as during this period animals are able to perceive pain and distress. Our results show that only higher concentrations of CO2 (CO2 60, 100) and isoflurane (5%) induced surgical tolerance within 300 s in both strains, with CO2 100 being the fastest acting inhalant anesthetic. The potency of halogenated ethers depended on the mouse strain, with C57Bl/6J being more susceptible than NMRI mice. Behavioral analysis revealed no specific signs of distress, e. g. stress-induced grooming, and pain, i. e. audible vocalizations, for all inhalant gases. However, adrenaline and noradrenaline plasma concentrations were increased, especially in NMRI mice exposed to CO2 in high concentrations, whereas we did not observe such increase in animals exposed to isoflurane or sevoflurane. Escape latencies in the approach-avoidance test using C57Bl/6J mice did not differ between the three inhalant gases, however, some animals became recumbent during isoflurane and sevoflurane but not during CO2 exposure. The rise in catecholamine concentrations suggests that CO2 exposure might be linked to a higher stress response compared to isoflurane and sevoflurane exposure, although we did not observe a behavioral correlate for that. Follow-up studies investigating other fast-acting stress hormones and central anxiety circuits are needed to confirm our findings.
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Affiliation(s)
- Nicole Marquardt
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Malte Feja
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- * E-mail:
| | - Hana Hünigen
- Institute of Veterinary Anatomy, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Johanna Plendl
- Institute of Veterinary Anatomy, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Lena Menken
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Heidrun Fink
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Bettina Bert
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
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22
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Harikrishnan VS, Hansen AK, Abelson KS, Sørensen DB. A comparison of various methods of blood sampling in mice and rats: Effects on animal welfare. Lab Anim 2017; 52:253-264. [PMID: 29165033 DOI: 10.1177/0023677217741332] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This study was conducted to investigate the effects of blood sampling on animal welfare in a total of 60 NTac:SD rats and 72 C57BL/6NTac mice of both sexes. Blood was sampled either by sublingual vein puncture, tail vein puncture or by retrobulbar plexus/sinus puncture under light isoflurane anaesthesia and, additionally, by facial vein puncture in mice. Non-punctured animals as well as isoflurane-anaesthetised animals were used as controls. Pre- and post-puncture sucrose intake (1.5% w/w) was measured in rats, and nest building scores were studied in mice for 24 h post-puncture. Post-puncture activity and anxiety levels of rats and mice were measured using an elevated plus maze test and an open field test. Stress levels 24 h post-puncture were assessed by analysing faecal corticosteroid metabolites. Sucrose intake and faecal corticosteroid levels were not affected by the blood sampling procedures. Rats showed reduced activity in the open field test and an increased level of anxiety in the elevated plus maze test following retrobulbar plexus puncture and isoflurane anaesthesia. In mice, nest building activity was affected in all the groups compared with the control group, except for animals subjected to facial vein puncture. Retrobulbar sinus puncture, tail vein puncture and sublingual puncture in mice resulted in reduced activity and increased anxiety. We conclude that, of the tested methods, puncture of the tail vein and the sublingual vein have the least adverse effects in rats, whereas facial vein puncture had the least adverse effects on the welfare parameters in mice.
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Affiliation(s)
- V S Harikrishnan
- 1 Division of Laboratory Animal Science, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, India.,2 Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Axel K Hansen
- 2 Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Klas Sp Abelson
- 3 Department of Experimental Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Dorte B Sørensen
- 2 Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
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23
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Hohlbaum K, Bert B, Dietze S, Palme R, Fink H, Thöne-Reineke C. Severity classification of repeated isoflurane anesthesia in C57BL/6JRj mice-Assessing the degree of distress. PLoS One 2017; 12:e0179588. [PMID: 28617851 PMCID: PMC5472303 DOI: 10.1371/journal.pone.0179588] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/01/2017] [Indexed: 01/22/2023] Open
Abstract
According to the EU Directive 2010/63, the severity of a procedure has to be classified as mild, moderate or severe. General anesthesia is thought to be mild, but the Directive does not differentiate between single and repeated anesthesia. Therefore, we investigated the impact of repeated administration of isoflurane, the most commonly used inhalation anesthetic, on the well-being of adult C57BL/6JRj mice, in comparison to single administrations and to untreated animals, when applied six times for 45 min at an interval of 3–4 days. For the animals anesthetized, excitations, phases of anesthesia, and vital parameters were monitored. Well-being after anesthesia was assessed using a behavioral test battery including luxury behavior like burrowing and nest building behavior, the Mouse Grimace Scale (MGS), the free exploratory paradigm for anxiety-related behavior, home cage activity and the rotarod test for activity, as well as food intake and body weight. Additionally, hair corticosterone and fecal corticosterone metabolites were measured. Our results show that nest building behavior, home cage activity, body weight, and corticosterone concentrations were not influenced by anesthesia, whereas changes in burrowing behavior, the MGS, food intake, and the free exploratory behavior indicated that the well-being of the mice was more affected by repeated than single isoflurane anesthesia. This effect depended on the sex of the animals, with female mice being more susceptible than male mice. However, repeated isoflurane anesthesia caused only short-term mild distress and impairment of well-being, mainly in the immediate postanesthetic period. Well-being stabilized at 8 days after the last anesthesia, at the latest. Therefore, we conclude that when using our anesthesia protocol, the severity of both single and repeated isoflurane anesthesia in C57BL/6JRj mice can be classified as mild. However, within the mild severity category, repeated isoflurane anesthesia ranks higher than single isoflurane anesthesia. Additionally, our results imply that male and female mice can differently perceive the severity of a procedure.
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Affiliation(s)
- Katharina Hohlbaum
- Institute of Animal Welfare, Animal Behavior and Laboratory Animal Science, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- * E-mail:
| | - Bettina Bert
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Silke Dietze
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Rupert Palme
- Unit of Physiology, Pathophysiology and Experimental Endocrinology, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Heidrun Fink
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Christa Thöne-Reineke
- Institute of Animal Welfare, Animal Behavior and Laboratory Animal Science, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
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24
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A Good Death? Report of the Second Newcastle Meeting on Laboratory Animal Euthanasia. Animals (Basel) 2016; 6:ani6090050. [PMID: 27563926 PMCID: PMC5035945 DOI: 10.3390/ani6090050] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 07/29/2016] [Accepted: 08/11/2016] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Millions of laboratory animals are killed each year worldwide. However, there is a lack of consensus regarding what methods of killing are humane for many species and stages of development. This report summarises research findings and discussions from an international meeting of experts and stakeholders, with recommendations to inform good practice for humane killing of mice, rats and zebrafish. It provides additional guidance and perspectives for researchers designing projects that involve euthanasing animals, researchers studying aspects of humane killing, euthanasia device manufacturers, regulators, and institutional ethics or animal care and use committees that wish to review local practice. Abstract Millions of laboratory animals are killed each year worldwide. There is an ethical, and in many countries also a legal, imperative to ensure those deaths cause minimal suffering. However, there is a lack of consensus regarding what methods of killing are humane for many species and stages of development. In 2013, an international group of researchers and stakeholders met at Newcastle University, United Kingdom to discuss the latest research and which methods could currently be considered most humane for the most commonly used laboratory species (mice, rats and zebrafish). They also discussed factors to consider when making decisions about appropriate techniques for particular species and projects, and priorities for further research. This report summarises the research findings and discussions, with recommendations to help inform good practice for humane killing.
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25
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Valentim AM, Guedes SR, Pereira AM, Antunes LM. Euthanasia using gaseous agents in laboratory rodents. Lab Anim 2015; 50:241-53. [PMID: 26609130 DOI: 10.1177/0023677215618618] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Several questions have been raised in recent years about the euthanasia of laboratory rodents. Euthanasia using inhaled agents is considered to be a suitable aesthetic method for use with a large number of animals simultaneously. Nevertheless, its aversive potential has been criticized in terms of animal welfare. The data available regarding the use of carbon dioxide (CO2), inhaled anaesthetics (such as isoflurane, sevoflurane, halothane and enflurane), as well as carbon monoxide and inert gases are discussed throughout this review. Euthanasia of fetuses and neonates is also addressed. A table listing currently available information to ease access to data regarding euthanasia techniques using gaseous agents in laboratory rodents was compiled. Regarding better animal welfare, there is currently insufficient evidence to advocate banning or replacing CO2 in the euthanasia of rodents; however, there are hints that alternative gases are more humane. The exposure to a volatile anaesthetic gas before loss of consciousness has been proposed by some scientific studies to minimize distress; however, the impact of such a measure is not clear. Areas of inconsistency within the euthanasia literature have been highlighted recently and stem from insufficient knowledge, especially regarding the advantages of the administration of isoflurane or sevoflurane over CO2, or other methods, before loss of consciousness. Alternative methods to minimize distress may include the development of techniques aimed at inducing death in the home cage of animals. Scientific outcomes have to be considered before choosing the most suitable euthanasia method to obtain the best results and accomplish the 3Rs (replacement, reduction and refinement).
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Affiliation(s)
- A M Valentim
- Laboratory Animal Science, Institute of Molecular and Cell Biology (IBMC), University of Porto, Rua do Campo Alegre, Porto, Portugal Institute for Research and Innovation in Health (i3S), University of Porto, Rua Alfredo Allen, Porto, Portugal
| | - S R Guedes
- Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB) and Veterinary Sciences Department, University of Trás-os-Montes and Alto Douro (UTAD), Quinta de Prados, Vila Real, Portugal
| | - A M Pereira
- Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB) and Veterinary Sciences Department, University of Trás-os-Montes and Alto Douro (UTAD), Quinta de Prados, Vila Real, Portugal
| | - L M Antunes
- Laboratory Animal Science, Institute of Molecular and Cell Biology (IBMC), University of Porto, Rua do Campo Alegre, Porto, Portugal Institute for Research and Innovation in Health (i3S), University of Porto, Rua Alfredo Allen, Porto, Portugal Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB) and Veterinary Sciences Department, University of Trás-os-Montes and Alto Douro (UTAD), Quinta de Prados, Vila Real, Portugal
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Boulanger Bertolus J, Nemeth G, Makowska IJ, Weary DM. Rat aversion to sevoflurane and isoflurane. Appl Anim Behav Sci 2015. [DOI: 10.1016/j.applanim.2014.12.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Testing three measures of mouse insensibility following induction with isoflurane or carbon dioxide gas for a more humane euthanasia. Appl Anim Behav Sci 2015. [DOI: 10.1016/j.applanim.2014.11.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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