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Amendola L, Xu N, Weary DM. Rats move nesting materials to create different functional areas: Short report. Lab Anim 2023; 57:75-78. [PMID: 36173016 PMCID: PMC9968993 DOI: 10.1177/00236772221122132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Here we document how rats separate their living space into different functional regions. Five groups of four female Sprague Dawley rats were housed in caging systems that consisted of two standard cages connected by a tube. Both cages were provided with the same amount of bedding and nesting materials, but only one contained food and water. Nesting cover and weight of each cage were measured once a week for five weeks during cage cleaning. We found that the cages with food and water had 9% less nesting material coverage but had gained 90% more weight when compared with cages where food and water were absent. These results indicate that, when provided with separate spaces, rats move nesting materials away from the cage containing food and water sources, but preferentially excrete in the cage with water and food.
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Affiliation(s)
| | | | - Daniel M Weary
- Daniel Weary, The University of British Columbia, 2357 Main Mall, Vancouver, BC British Columbia V6T 1Z4, Canada.
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2
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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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3
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Hickman DL. Evaluation of Carbon Dioxide Euthanasia of Female Sprague Dawley Rats Alone or With Unfamiliar Conspecifics. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2022; 61:195-200. [PMID: 35101159 PMCID: PMC8956221 DOI: 10.30802/aalas-jaalas-21-000051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/07/2021] [Accepted: 10/09/2021] [Indexed: 06/14/2023]
Abstract
Most studies evaluating methods of euthanasia to date have focused on the euthanasia of individual animals. However, larger chambers are commonly used to euthanize multiple cages of animals at once. This study evaluated the use of a commercially available system for euthanasia of 1, 2, or 4 cages containing an individual female Sprague-Dawley rat using volume per minute displacement rates (VDR/min) of either 25% or 50% of 100% carbon dioxide. Animal wellbeing was assessed based on physiologic changes (serum noradrenaline and corticosterone) and behavioral assessments (relative frequency of rearing, line crossing, and grooming). The 25% VDR/min was associated with a significantly longer time to loss of consciousness, but this was not associated with significant physiologic or behavioral changes. The 50% VDR/min treatment group was associated with significant increases in the relative frequency of movement from 1 side of the cage to the other. Increases in the relative frequency of rears were detected in the 25% VDR/min treatment group when 2 or 4 rats were in the chamber as compared with a single rat in the chamber. The absence of significant physiologic changes suggest that the behavioral changes may have been associated with the novelty of the euthanasia experience rather than with distress. The location of the cage within the chamber did not significantly affect any of the measured parameters at either 25% or 50% VDR/min. These data suggest that groups of rats euthanized in these chambers are not experiencing decreases in their welfare.
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Affiliation(s)
- Debra L Hickman
- School of Medicine, Indiana University, Indianapolis, Indiana
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4
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Améndola L, Ratuski A, Weary DM. Individual differences in rat sensitivity to CO2. PLoS One 2021; 16:e0245347. [PMID: 33481851 PMCID: PMC7822239 DOI: 10.1371/journal.pone.0245347] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 12/28/2020] [Indexed: 11/18/2022] Open
Abstract
Feelings of fear, anxiety, dyspnea and panic when inhaling carbon dioxide (CO2) are variable among humans, in part due to differences in CO2 sensitivity. Rat aversion to CO2 consistently varies between individuals; this variation in aversion may reflect CO2 sensitivity, but other personality traits could also account for individual differences in aversion. The aims of this study were to 1) assess the stability of individual differences in rat aversion to CO2, 2) determine if individual differences in sweet reward motivation are associated with variation in aversion to CO2, and 3) assess whether variation in aversion to CO2 is related to individual differences in motivation to approach gains (promotion focus) or maintain safety (prevention focus). Twelve female Sprague Dawley rats were exposed multiple times at three different ages (3, 9 and 16 months old) to CO2 in approach-avoidance testing to assess motivation to avoid CO2 against motivation to gain sweet rewards. Rats were also tested for motivation to find hidden sweet rewards, and for their motivation to approach rewards or darkness. Tolerance to CO2 increased with repeated exposures and was higher at older ages. Individual differences in aversion to CO2 were highly repeatable but unrelated to motivation for sweet rewards or the strength of promotion and prevention focus. These results indicate that individual differences in aversion to CO2 reflect variation in CO2 sensitivity.
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Affiliation(s)
- Lucía Améndola
- Animal Welfare Program, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anna Ratuski
- Animal Welfare Program, University of British Columbia, Vancouver, British Columbia, Canada
| | - Daniel M. Weary
- Animal Welfare Program, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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5
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Tadvalkar G, Pal-Ghosh S, Pajoohesh-Ganji A, Stepp MA. The impact of euthanasia and enucleation on mouse corneal epithelial axon density and nerve terminal morphology. Ocul Surf 2020; 18:821-828. [PMID: 32798735 DOI: 10.1016/j.jtos.2020.07.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 07/27/2020] [Accepted: 07/29/2020] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Here we study the impact of using either CO2 gas or cervical dislocation (CD) for euthanasia and using different techniques to enucleate the eye on preserving axonal density and morphology of the intraepithelial corneal nerves (ICNs). OBJECTIVES To determine whether using CO2 gas or CD for euthanasia and enucleating by cutting or pulling eyes out impacts axon density and nerve terminal morphology in the mouse cornea. METHODS Mice were euthanized by CO2 gas or CD; the impact of delaying fixation for 5 min post-euthanasia was also assessed. We tested two different techniques to enucleate the eyes: cutting the optic nerve by curved scissors or pulling the eye out. A minimum of 10 corneas from 5 male and female BALB/c mice were used for each variable. Axons and intraepithelial corneal nerve terminals (ICNTs) were visualized utilizing βIII tubulin and L1CAM and quantified using confocal microscopy. RESULTS The variations seen in axon density between individual mice are not gender- or euthanasia-dependent. A significant reduction in axon density and loss of ICNT morphology are observed in eyes enucleated by pulling the optic nerve out. Similar results are obtained in male and female mice. CONCLUSION While the variations tested in euthanasia do not affect axon density in male and female mouse corneas, enucleation by proptosing and gently cutting out the eyes yields increased axon density and improved ICNT morphology compared to pulling eyes out and leaving the optic nerve attached.
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Affiliation(s)
- Gauri Tadvalkar
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA
| | - Sonali Pal-Ghosh
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA
| | - Ahdeah Pajoohesh-Ganji
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA
| | - Mary Ann Stepp
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA; Department of Ophthalmology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA.
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Abstract
The aim of this review is to summarize evidence regarding rat emotional experiences during carbon dioxide (CO2) exposure. The studies reviewed show that CO2 exposure is aversive to rats, and that rats respond to CO2 exposure with active and passive defense behaviors. Plasma corticosterone and bradycardia increased in rats exposed to CO2. As with anxiogenic drugs, responses to CO2 are counteracted by the administration of anxiolytics, SRIs, and SSRI's. Human studies reviewed indicate that, when inhaling CO2, humans experience feelings of anxiety fear and panic, and that administration of benzodiazepines, serotonin precursors, and SSRIs ameliorate these feelings. In vivo and in vitro rat studies reviewed show that brain regions, ion channels, and neurotransmitters involved in negative emotional responses are activated by hypercapnia and acidosis associated with CO2 exposure. On the basis of the behavioral, physiological, and neurobiological evidence reviewed, we conclude that CO2 elicits negative emotions in rats.
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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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8
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Améndola L, Ratuski A, Weary DM. Variation in the onset of CO 2-induced anxiety in female Sprague Dawley rats. Sci Rep 2019; 9:19007. [PMID: 31831816 PMCID: PMC6908729 DOI: 10.1038/s41598-019-55493-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 11/26/2019] [Indexed: 12/27/2022] Open
Abstract
Carbon dioxide (CO2) is commonly used to kill laboratory rats. Rats find CO2 aversive and aversion varies between individuals, indicating that rats vary in CO2 sensitivity. Healthy humans experience feelings of anxiety at concentrations similar to those avoided by rats, and these feelings are diminished by the administration of benzodiazepines. Our aim was to assess the effects of the benzodiazepine midazolam on individual thresholds of rat aversion to CO2. Six female Sprague Dawley rats were repeatedly exposed to CO2 gradual-fill in approach-avoidance testing. The first three exposures were to a control-treatment followed by three exposures to midazolam (0.375 mg/kg). Within each treatment aversion to CO2 was not affected by exposure number; however, tolerance increased from an average of 10.7% CO2 avoided during control sessions, to 15.5% CO2 avoided when treated with midazolam. These results indicate that rats experience anxiety when exposed to CO2, and that variation in rat CO2 sensitivity is driven by individual differences in the onset of these feelings of anxiety. No rat tolerated CO2 concentrations required to induce loss of consciousness.
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Affiliation(s)
- Lucía Améndola
- Animal Welfare Program, University of British Columbia, 2357 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Anna Ratuski
- Animal Welfare Program, University of British Columbia, 2357 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Daniel M Weary
- Animal Welfare Program, University of British Columbia, 2357 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada.
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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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Améndola L, Weary DM. Evidence for consistent individual differences in rat sensitivity to carbon dioxide. PLoS One 2019; 14:e0215808. [PMID: 31017958 PMCID: PMC6481838 DOI: 10.1371/journal.pone.0215808] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 04/09/2019] [Indexed: 12/24/2022] Open
Abstract
Carbon dioxide (CO2) gradual-fill is commonly used to kill laboratory rats, but this use remains controversial due to a lack of agreement between studies. Inconsistencies may arise from differences in behaviors measured (e.g. active versus passive behaviors), in how rats cope with threats, or in rat sensitivity to CO2. The aims of the current study were to 1) describe active and passive responses during CO2 forced exposure, 2) determine if these responses are consistent within individuals and across aversive stimuli, 3) assess individual differences in aversion to CO2 in aversion-avoidance and approach-avoidance tests and 4) determine how responses in aversion tests relate to individual differences in behavior during forced exposure. Twelve Sprague Dawley female rats were exposed twice to three treatments: CO2, oxygen (O2), and fox scent, and were exposed to CO2 twice in each aversion test. The change in behavior from baseline was higher for rearing and locomotion when rats were exposed to CO2 than when exposed to O2 and fox scent. Responses varied among rats but were consistent across multiple tests within rats. For example, rearing was consistent within individuals between two exposures to CO2. Similarly, the strength of aversion was consistent within individuals across multiple exposures to CO2 in aversion-avoidance and approach-avoidance testing. Latency to avoid CO2 in aversion-avoidance tests was negatively correlated with rearing during CO2 forced exposure. Collectively, these results indicate that rat responses to CO2 vary between (but are consistent within) individuals, suggesting that rats vary in CO2 sensitivity. However, even the less responsive rats avoided CO2 concentrations far below those necessary to achieve unconsciousness, indicating that all rats likely experience negative states when euthanized with CO2.
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Affiliation(s)
- Lucía Améndola
- Animal Welfare Program, University of British Columbia, Vancouver, British Columbia, Canada
| | - Daniel M. Weary
- Animal Welfare Program, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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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: 40] [Impact Index Per Article: 6.7] [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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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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13
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The validity of using an approach-avoidance test to measure the strength of aversion to carbon dioxide in rats. Appl Anim Behav Sci 2008. [DOI: 10.1016/j.applanim.2008.03.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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