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Bonnichsen R, Hansen C, Søndergaard JR, Schrøder-Petersen DL. Effect of Stocking Density during CO 2 Stunning of Pigs on Induction Time and Activity Level Measured Using AI. Animals (Basel) 2024; 14:1953. [PMID: 38998065 PMCID: PMC11240643 DOI: 10.3390/ani14131953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 06/26/2024] [Accepted: 06/28/2024] [Indexed: 07/14/2024] Open
Abstract
During the CO2 stunning of pigs, a variation in their reaction to the gas and the duration of the induction period is observed. The stunning process can be affected by several conditions, such as stressful events and previous experiences, but the stocking density in the gondola may also have an impact. The objective was to investigate the effect of stocking density on the stunning process under commercial conditions. To quantify the pigs' reactions under industrial settings with a stocking density of up to eight pigs pr. Gondola (3.91 m2), the activity level was measured using an AI solution. Compared with a simulation of the expected induction period, a significantly longer induction period was found in gondolas containing seven and eight pigs (p < 0.001) but not when the gondolas contained three or four pigs. Both high and mean activity levels were significantly higher when stocking density was increased from three or four pigs to seven or eight pigs. The stunning process was thus negatively affected when increasing the stocking density. More knowledge is needed to explain this effect and to make statements on optimal stocking density. The measured activity levels may be a useful tool for obtaining information under commercial conditions and for documenting animal welfare.
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Affiliation(s)
- Rikke Bonnichsen
- Department of Food and Production, Danish Technological Institute, Gregersensvej, DK-2630 Taastrup, Denmark; (C.H.); (J.R.S.); (D.L.S.-P.)
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Janicka W, Wilk I, Próchniak T. Does social motivation mitigate fear caused by a sudden sound in horses? Anim Cogn 2023; 26:1649-1660. [PMID: 37450226 PMCID: PMC10442260 DOI: 10.1007/s10071-023-01805-x] [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: 02/11/2023] [Revised: 06/01/2023] [Accepted: 06/23/2023] [Indexed: 07/18/2023]
Abstract
Living in a herd has multiple advantages for social species and is a primary survival strategy for prey. The presence of conspecifics, identified as a social buffer, may mitigate the individual stress response. Social isolation is, therefore, particularly stressful for horses, which are gregarious animals. However, they are not equally vulnerable to separation from the group. We tested whether more and less socially dependent horses and independent individuals would differ in their responses to novel and sudden sounds occurring in two contexts: non-social and social motivation. Twenty warmblood horses were first exposed to two social tests: to evaluate the level of social dependence (rate of restless behaviour; social isolation) and the quantity and the quality of interactions in which they were involved (stay on a paddock). Two fear audio tests were then performed to compare the responses to sudden sounds while feeding (non-social motivation; control trial) and while moving towards the herd (social motivation; experimental trial). Socially dependent horses showed more pronounced avoidance behaviour and needed much more time to resume feeding during the control trial. Hence, dependent individuals appeared to be more fearful. However, during an experimental trial, horses of both groups tended to ignore the sound or paid only limited attention to the stimulus, continuing to move forward towards their conspecifics. Thus, social motivation may mitigate fear caused by a frightening stimulus and make fearful and dependent horses more prone to face a potentially stressful event. This finding should be taken into account in horse training and management.
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Affiliation(s)
- Wiktoria Janicka
- Department of Horse Breeding and Use, University of Life Sciences in Lublin, 13 Akademicka Street, Lublin, Poland
| | - Izabela Wilk
- Department of Horse Breeding and Use, University of Life Sciences in Lublin, 13 Akademicka Street, Lublin, Poland.
| | - Tomasz Próchniak
- Institute of Biological Basis of Animal Production, University of Life Sciences in Lublin, 13 Akademicka Street, Lublin, Poland
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Ding J, Yu Y, Luo M, Fang X, Tan D, Qin H, Ren X, Zhang Y, Luo T, Chen L, Yu W, Zhu Z. Thrifty effect of subanesthetic-dose S-ketamine on postoperative opioids and its safety and analgesic effectiveness: A prospective, triple-blind, randomized controlled, polycentric clinical trial. IBRAIN 2023; 9:171-182. [PMID: 37786549 PMCID: PMC10529155 DOI: 10.1002/ibra.12104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 04/19/2023] [Accepted: 04/30/2023] [Indexed: 10/04/2023]
Abstract
Aim To investigate the thrifty effects of subanesthetic-dose S-ketamine on postoperative opioids and its safety and analgesic efficacy. Methods Four-hundred and twenty patients were divided into the control group (CON group), the S-ketamine 0.2 mg/kg group (ES0.2 group), and the S-ketamine 0.3 mg/kg group (ES0.3 group) randomly. Major indicators include the Visual Analogue Scale (VAS), the times of compression with analgesic pumps after surgery, and analgesic drug consumption from anesthesia induction to 48 h after surgery. Minor records include vital signs, the use of vasoactive drugs, the Ramsay scores, the occurrence of adverse events including nervous system reaction, and the patient's satisfaction with anesthesia. Results Compared with the CON group, VAS scores decreased in the ES0.2 and ES0.3 groups (p < 0.05). At 10 min after extubation, the VAS scores of the ES0.3 group were lower than that of the ES0.2 group (p < 0.05). The total number of compression with analgesic pumps of the ES0.3 group was lower than that of the CON group (p < 0.05). The opioid consumption after surgery of the ES0.3 group was lower than those of the CON group and the ES0.2 group (p < 0.05). The ES0.3 group's heart rate (HR) was faster but the use of vasoactive, drug consumption was less than the other two groups (p < 0.05). There were no significant differences in the incidence of postoperative adverse events and anesthetic satisfaction among the three groups. Conclusion Subanesthetic-dose S-ketamine at 0.2-0.3 mg/kg especially the 0.3 mg/kg in general anesthesia induction can safely and effectively reduce postoperative pain and save postoperative opioid consumption.
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Affiliation(s)
- Jun Ding
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiGuizhouChina
| | - Yun‐Mei Yu
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiGuizhouChina
| | - Man Luo
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiGuizhouChina
| | - Xu Fang
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiGuizhouChina
| | - Dan‐Dan Tan
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiGuizhouChina
| | - Han‐Rui Qin
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiGuizhouChina
| | - Xue‐Feng Ren
- Department of AnesthesiologyPeople's Hospital of Anshuan CityAnshunGuizhouChina
| | - Yong‐Guo Zhang
- Department of AnesthesiologyPeople's Hospital of QiannanQiannanGuizhouChina
| | - Tao Luo
- Department of AnesthesiologyThe People's Hospital of TongrenTongrenGuizhouChina
| | - Lei Chen
- Department of AnesthesiologyQian Xi Nan People's HospitalQianxinanGuizhouChina
| | - Wan‐Qiu Yu
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiGuizhouChina
| | - Zhao‐Qiong Zhu
- Department of AnesthesiologyAffiliated Hospital of Zunyi Medical UniversityZunyiGuizhouChina
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Lorbach JN, Campler MR, Youngblood B, Farnell MB, Beyene TJ, Kieffer J, Moeller SJ, Arruda AG, Bowman AS. Comparison of Gaseous and Water-Based Medium-Expansion Foam Depopulation Methods in Cull Sows. Animals (Basel) 2021; 11:ani11113179. [PMID: 34827911 PMCID: PMC8614275 DOI: 10.3390/ani11113179] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/04/2021] [Accepted: 11/04/2021] [Indexed: 01/17/2023] Open
Abstract
Simple Summary In the face of a swine health crisis, emerging zoonotic diseases or environmental catastrophe, the mass depopulation of swine may be required to prevent the additional spread of disease and to minimize animal pain or suffering. Due to the increasing risk of global disease outbreaks, the U.S. swine industry needs feasible guidelines in place in preparation for such events. Current American Veterinary Medical Association (AVMA) approved swine depopulation methods can be difficult to implement under field conditions. Emergency depopulation using inhalants such as carbon dioxide (CO2) and nitrogen gas (N2) or the use of aspirated foam agents have been approved and conducted in poultry in the US, but are not approved for use in other livestock. Our findings, using cull sows, demonstrate that although CO2, N2 and aspirated foam combinations successfully killed all the animals, CO2 and aspirated foam did so in the shortest timeframe. In addition, the use of aspirated foam was as effective as CO2 for sow depopulation while having potential operational advantages, such as no use of lethal gases and reduced risk of associated equipment failure. Abstract The U.S. swine industry is currently inadequately prepared to counteract the increasing threat of high-consequence diseases. Although approved and preferred depopulation guidelines exist, ventilation shutdown (VSD+) is currently the only method being deployed during a state of emergency to depopulate large swine populations. However, the permitted use of VSD+ during constrained circumstances has been criticized due to raised swine welfare concerns. The objective of this study was to investigate the effectiveness of carbon dioxide gas (CO2), nitrogen gas (N2), compressed air foam (CAF), compressed nitrogen foam (CAF-N2) and aspirated foam (AF) during a 15-min dwell time on adult swine in an emergency depopulation situation. A small-scale trial using 12 sows per depopulation method showed the highest efficiency to induce cessation of movement for AF and CO2 (186.0 ± 48 vs. 202.0 ± 41, s ± SD). The ease of implementation and safety favored AF for further investigation. A large-scale field study using AF to depopulate 134 sows in modified rendering trailers showed a mean fill time of 103.8 s (SD: 5.0 s) and cessation of movement of 128.0 s (SD: 18.6 s) post filling. All sows were confirmed dead post-treatment for both trials. The implementation of AF in modified rendering trailers may allow for a safe and reliable method that allows for the expedient and mobile depopulation of both small and large numbers of sows during an emergency.
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Affiliation(s)
- Joshua N. Lorbach
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43215, USA; (J.N.L.); (M.R.C.); (B.Y.); (A.G.A.)
| | - Magnus R. Campler
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43215, USA; (J.N.L.); (M.R.C.); (B.Y.); (A.G.A.)
| | - Brad Youngblood
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43215, USA; (J.N.L.); (M.R.C.); (B.Y.); (A.G.A.)
| | - Morgan B. Farnell
- Department of Poultry Science, College of Agriculture & Life Sciences, Texas A & M University, College Station, TX 77843, USA;
| | - Tariku J. Beyene
- Center for Surgical Outcomes Research, The Research Institute at Nationwide Children’s Hospital, Columbus, OH 43215, USA;
| | - Justin Kieffer
- Department of Animal Sciences, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Columbus, OH 43215, USA; (J.K.); (S.J.M.)
| | - Steven J. Moeller
- Department of Animal Sciences, College of Food, Agricultural, and Environmental Sciences, The Ohio State University, Columbus, OH 43215, USA; (J.K.); (S.J.M.)
| | - Andréia G. Arruda
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43215, USA; (J.N.L.); (M.R.C.); (B.Y.); (A.G.A.)
| | - Andrew S. Bowman
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43215, USA; (J.N.L.); (M.R.C.); (B.Y.); (A.G.A.)
- Correspondence:
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Bhujel A, Arulmozhi E, Moon BE, Kim HT. Deep-Learning-Based Automatic Monitoring of Pigs' Physico-Temporal Activities at Different Greenhouse Gas Concentrations. Animals (Basel) 2021; 11:3089. [PMID: 34827821 PMCID: PMC8614322 DOI: 10.3390/ani11113089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 10/27/2021] [Accepted: 10/28/2021] [Indexed: 12/29/2022] Open
Abstract
Pig behavior is an integral part of health and welfare management, as pigs usually reflect their inner emotions through behavior change. The livestock environment plays a key role in pigs' health and wellbeing. A poor farm environment increases the toxic GHGs, which might deteriorate pigs' health and welfare. In this study a computer-vision-based automatic monitoring and tracking model was proposed to detect pigs' short-term physical activities in the compromised environment. The ventilators of the livestock barn were closed for an hour, three times in a day (07:00-08:00, 13:00-14:00, and 20:00-21:00) to create a compromised environment, which increases the GHGs level significantly. The corresponding pig activities were observed before, during, and after an hour of the treatment. Two widely used object detection models (YOLOv4 and Faster R-CNN) were trained and compared their performances in terms of pig localization and posture detection. The YOLOv4, which outperformed the Faster R-CNN model, was coupled with a Deep-SORT tracking algorithm to detect and track the pig activities. The results revealed that the pigs became more inactive with the increase in GHG concentration, reducing their standing and walking activities. Moreover, the pigs shortened their sternal-lying posture, increasing the lateral lying posture duration at higher GHG concentration. The high detection accuracy (mAP: 98.67%) and tracking accuracy (MOTA: 93.86% and MOTP: 82.41%) signify the models' efficacy in the monitoring and tracking of pigs' physical activities non-invasively.
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Affiliation(s)
- Anil Bhujel
- Department of Biosystems Engineering, Institute of Smart Farm, Gyeongsang National University, Jinju 52828, Korea; (A.B.); (E.A.)
- Ministry of Communication and Information Technology, Singha Durbar, Kathmandu 44600, Nepal
| | - Elanchezhian Arulmozhi
- Department of Biosystems Engineering, Institute of Smart Farm, Gyeongsang National University, Jinju 52828, Korea; (A.B.); (E.A.)
| | - Byeong-Eun Moon
- Smart Farm Research Center, Gyeongsang National University, Jinju 52828, Korea;
| | - Hyeon-Tae Kim
- Department of Biosystems Engineering, Institute of Smart Farm, Gyeongsang National University, Jinju 52828, Korea; (A.B.); (E.A.)
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Terlouw EMC, Deiss V, Astruc T. Comparing Gas and Electrical Stunning: Effects on Meat Quality of Pigs when Pre-Stunning Physical Activity is Minimal. Foods 2021; 10:319. [PMID: 33546330 PMCID: PMC7913529 DOI: 10.3390/foods10020319] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/25/2021] [Accepted: 01/27/2021] [Indexed: 11/17/2022] Open
Abstract
A total of thirty pigs were experimentally slaughtered using gas (80% CO2 in air, 90 s; 30% CO2/70% N2O; 90 s) or electrical stunning (1.3 A, 10 s). Stunning may accelerate post-mortem muscle metabolism, due to psychological stress and/or muscle contractions. The specific effects of the stunning method were studied by limiting pre-stunning physical activity and stress: pigs were driven in a trolley from the rearing to the stunning site (6.5 m) and immediately slaughtered. Bleeding efficiency and carcass characteristics were similar and satisfactory for all stunning methods. Early post-mortem pH decline in the Longissimus lumborum was faster following gas compared to electrical stunning. The pH of other muscles was not influenced; color and drip loss showed minor effects. Hence, results are in contrast to current beliefs: compared to electrical stunning, following gas stunning, the stress and muscle contractions during the induction of unconsciousness have a slightly greater impact on Longissimus lumborum muscle metabolism; differences are minor and limited to certain muscles only.
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Affiliation(s)
- E. M. Claudia Terlouw
- INRAE, VetAgro Sup, UMR Herbivores, Université Clermont Auvergne, F-63122 Saint-Genès-Champanelle, France;
| | - Véronique Deiss
- INRAE, VetAgro Sup, UMR Herbivores, Université Clermont Auvergne, F-63122 Saint-Genès-Champanelle, France;
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Sindhøj E, Lindahl C, Bark L. Review: Potential alternatives to high-concentration carbon dioxide stunning of pigs at slaughter. Animal 2021; 15:100164. [PMID: 33461892 DOI: 10.1016/j.animal.2020.100164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 12/14/2020] [Accepted: 12/14/2020] [Indexed: 10/22/2022] Open
Abstract
Using carbon dioxide (CO2) for stunning pigs at slaughter is common in Europe. The use of group stunning is a major advantage with CO2, which is done without restraining the pigs and with minimized human contact. However, high concentrations of CO2 have been known for decades to cause pain, fear and distress in pigs before loss of consciousness, and the stunning method is clearly associated with animal welfare concerns. This study reviewed the scientific literature to find recent developments or evaluations of alternative methods that could lead to the replacement of CO2 for stunning pigs at slaughter. Potential alternative methods found in the literature were described and then assessed to identify specific research and development needs for their further development. Only 15 empirical studies were found in the search of peer-reviewed literature since 2004, which is less than one per year. Furthermore, half of the studies focused on evaluating methods to improve high-concentration CO2 stunning rather than an alternative to CO2. Since no clear alternative has emerged, nor a method to improve CO2 stunning, there is obviously a strong need to focus research and development to find solutions for improving animal welfare when stunning pigs at slaughter.
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Affiliation(s)
- E Sindhøj
- Department of Agriculture and Food, RISE Research Institutes of Sweden, P.O. Box 7033, 750 07 Uppsala, Sweden.
| | - C Lindahl
- Department of Agriculture and Food, RISE Research Institutes of Sweden, P.O. Box 7033, 750 07 Uppsala, Sweden
| | - L Bark
- Department of Agriculture and Food, RISE Research Institutes of Sweden, P.O. Box 7033, 750 07 Uppsala, Sweden
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Animal Welfare and Meat Quality Assessment in Gas Stunning during Commercial Slaughter of Pigs Using Hypercapnic-Hypoxia (20% CO 2 2% O 2) Compared to Acute Hypercapnia (90% CO 2 in Air). Animals (Basel) 2020; 10:ani10122440. [PMID: 33419236 PMCID: PMC7766013 DOI: 10.3390/ani10122440] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/08/2020] [Accepted: 12/17/2020] [Indexed: 11/16/2022] Open
Abstract
This study assessed aversion, stunning effectiveness, and product quality of nitrogen and carbon dioxide (CO2) mixtures used for stunning pigs. A total of 1852 slaughter pigs divided into two similar batches was assessed during routine slaughter in a Swedish commercial abattoir using either hypercapnic-hypoxia (20% CO2 and less than 2% O2; 20C2O) or hypercapnia (90% CO2; 90C) gas mixtures. Behavioral indicators of aversion and discomfort were recorded. After exposure, the stunning quality was assessed through brainstem reflexes. After slaughter, the pH and electric conductivity of carcasses were assessed to estimate the incidence of pale, soft, and exudative (PSE) pork, and the presence of ecchymosis were inspected. Compared to 90C, pigs exposed to 20C2O showed a later (p < 0.05) onset of behaviors indicative of aversion, and a lower (p < 0.01) incidence of breathlessness. However, unconsciousness (i.e., losing posture) appeared earlier (p < 0.01) in 90C compared to 20C2O. In 90C, all (100%) pigs were adequately stunned, whereas in 20C2O a 7.4% of pigs showed signs of poor stunning, especially when oxygen concentrations were >2% (p < 0.001). The percentage of PSE carcasses was higher (p < 0.01) in 20C2O than 90C. In conclusion, compared to 90C, 20C2O reduced aversion and discomfort but showed lower stun effectiveness, especially when O2 was above 2%, and a slightly poorer pork quality.
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Natusch DJD, Aust PW, Khadiejah S, Ithnin H, Isa A, Zamzuri CK, Ganswindt A, DeNardo DF. Behavioral and corticosterone responses to carbon dioxide exposure in reptiles. PLoS One 2020; 15:e0240176. [PMID: 33022690 PMCID: PMC7538201 DOI: 10.1371/journal.pone.0240176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/21/2020] [Indexed: 11/19/2022] Open
Abstract
The use of carbon dioxide (CO2) exposure as a means of animal euthanasia has received considerable attention in mammals and birds but remains virtually untested in reptiles. We measured the behavioral responses of four squamate reptile species (Homalopsis buccata, Malayopython reticulatus, Python bivitattus, and Varanus salvator) to exposure to 99.5% CO2 for durations of 15, 30, or 90 minutes. We also examined alterations in plasma corticosterone levels of M. reticulatus and V. salvator before and after 15 minutes of CO2 exposure relative to control individuals. The four reptile taxa showed consistent behavioral responses to CO2 exposure characterized by gaping and minor movements. The time taken to lose responsiveness to stimuli and cessation of movements varied between 240–4260 seconds (4–71 minutes), with considerable intra- and inter-specific variation. Duration of CO2 exposure influenced the likelihood of recovery, which also varied among species (e.g., from 0–100% recovery after 30-min exposure). Plasma corticosterone concentrations increased after CO2 exposure in both V. salvator (18%) and M. reticulatus (14%), but only significantly in the former species. Based on our results, CO2 appears to be a mild stressor for reptiles, but the relatively minor responses to CO2 suggest it may not cause considerable distress or pain. However, our results are preliminary, and further testing is required to understand optimal CO2 delivery mechanisms and interspecific responses to CO2 exposure before endorsing this method for reptile euthanasia.
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Affiliation(s)
- Daniel J. D. Natusch
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, Australia
- EPIC Biodiversity, Frogs Hollow, NSW, Australia
- * E-mail:
| | - Patrick W. Aust
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Bushtick Environmental Services, Grantham, Lincolnshire, United Kingdom
| | - Syarifah Khadiejah
- Department of Wildlife and National Parks, Peninsular Malaysia, Kuala Lumpur, Malaysia
| | - Hartini Ithnin
- Department of Wildlife and National Parks, Peninsular Malaysia, Kuala Lumpur, Malaysia
| | - Ain Isa
- Department of Wildlife and National Parks, Peninsular Malaysia, Kuala Lumpur, Malaysia
| | - Che Ku Zamzuri
- Department of Wildlife and National Parks, Peninsular Malaysia, Kuala Lumpur, Malaysia
| | - Andre Ganswindt
- Endocrine Research Laboratory, Mammal Research Institute, Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
- Centre of Veterinary Wildlife Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, Onderstepoort, South Africa
| | - Dale F. DeNardo
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
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Wireless 'under the skull' epidural EEG and behavior in piglets during nitrous oxide or carbon dioxide gas euthanasia. Physiol Behav 2020; 227:113142. [PMID: 32822708 DOI: 10.1016/j.physbeh.2020.113142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/27/2020] [Accepted: 08/17/2020] [Indexed: 11/24/2022]
Abstract
Consciousness is central to animal welfare concerns. Its assessment is most often conducted based on behavior, with a poor understanding of the correspondence between behavior and the neurobiological processes that underlie the subjective experience of consciousness. Recording of brain electrical activity using electrodes placed under the skull improves EEG recording by minimizing artifacts from muscular or cardiac activities, and it can now be combined with wireless recording in free-moving animals. This experiment investigated the correspondence between wireless 'under the skull' epidural EEG and the behavior of 18 five-week-old female piglets undergoing nitrous oxide (N2O) or carbon dioxide (CO2) gradual fill gas euthanasia at 25% replacement rate per minute of the chamber volume. Piglets exposed to CO2 had a peak in EEG total power ('Ptot') during the flailing stage, whereas piglets exposed to N2O had a higher EEG 95% spectral edge frequency ('F95') during their initial explorative behavior phase and a drop in EEG median frequency ('F50') after loss of posture. Loss of posture without righting attempt, as the last behavioral state observed during euthanasia, preceded the onset of transitional EEG on average by 0.9 and 3.1 min (for CO2 and N2O treatments, respectively), and the onset of isoelectric EEG by 4.5 and 6.2 min (for CO2 and N2O treatments, respectively). Paddling movements occurred shortly before and during transitional EEG but never during isoelectric EEG, whereas gasps persisted after the EEG had become isoelectric. The dynamics of EEG spectral changes were complex to interpret in relation to the degree of consciousness, but isoelectric EEG as an unequivocal indicator of unconsciousness appeared several minutes after loss of posture with no righting attempt. This leaves a window of uncertainty in regards to the potential for consciousness after loss of posture during gradual fill gas euthanasia in piglets.
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