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Gas killing of rats: the effect of supplemental oxygen on aversion to carbon dioxide

Published online by Cambridge University Press:  11 January 2023

RD Kirkden ,
L Niel ,
SA Stewart  and
DM Weary
RD Kirkden*
Affiliation:
Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, BC, V6T 1Z4, Canada
L Niel
Affiliation:
Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, BC, V6T 1Z4, Canada
SA Stewart
Affiliation:
Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, BC, V6T 1Z4, Canada
DM Weary
Affiliation:
Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, BC, V6T 1Z4, Canada
*
* Contact for correspondence and requests for reprints: rdk500@cs.york.ac.uk
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Abstract

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High concentrations of carbon dioxide (CO2), used for killing laboratory rodents, are known to be more strongly aversive to rats than sweet food items are attractive. This study investigated whether the maintenance of a high oxygen (O2) concentration, using a gas mixture of 70% CO2 and 30% O2, would reduce aversion to CO2 during a gradual-fill procedure. Eight male Wistar rats, aged 10 months, were housed individually in an apparatus consisting of two cages, one higher than the other and joined by a tube. In a series of trials, subjects entered the lower cage for a reward of 20 sweet food items. The gas was turned on at the moment the rat started eating the reward items and flowed into the lower cage at a fixed rate. There were four treatments: 1) 100% CO2 at 14.5% cage volume min–1; 2) gas mixture at 14.5% min–1; 3) gas mixture at 21.0% min–1, which delivered CO2 at approximately 14.5% min–1 and 4) air, with each subject tested with each treatment four times. Measures of willingness to stay and eat in the lower cage (latency to stop eating, latency to leave and the number of reward items eaten) were much lower in all three gas treatments than in air, indicating that the CO2 and the CO2 + O2 mixture were both more strongly aversive than sweet food items were attractive. Comparing the gas mixture with 100% CO2, the latency to leave and the number of reward items eaten were slightly higher in the CO2 + O2 mixture at 21% min–1 than in CO2 at 14.5% min–1, indicating that the addition of O2 slightly reduced the aversiveness of CO2 in the gradual-fill procedure. This reduction is not enough to warrant recommending the use of CO2 + O2 mixtures for killing rats.

Keywords

animal welfareaversioncarbon dioxideeuthanasiaoxygenrat
Type
Articles
Information
Animal Welfare , Volume 17 , Issue 1 , February 2008 , pp. 79 - 87
Copyright
© 2008 Universities Federation for Animal Welfare

References

Ambrose, N, Wadham, J and Morton, D 2000 Refinement of euthanasia. In: Balls, M, van, Zeller A-M and Halder, ME (eds) Progress in the Reduction, Refinement and Replacement of Animal Experimentation pp 1159–1170. Elsevier: Amsterdam, The NetherlandsGoogle Scholar
American Veterinary Medical Association 2001 2000 Report of the AVMA Panel on Euthanasia. Journal of the American Veterinary Medical Association 218: 669–696CrossRefGoogle Scholar
Banzett, RB, Lansing, RW, Evans, KC and Shea, SA 1996 Stimulus-response characteristics of CO2-induced air hunger in normal subjects. Respiration Physiology 103: 19–31CrossRefGoogle ScholarPubMed
Blackshaw, JK, Fenwick, DC, Beattie, AW and Allan, DJ 1988 The behaviour of chickens, mice and rats during euthanasia with chloroform, carbon dioxide and ether. Laboratory Animals 22: 67–75CrossRefGoogle ScholarPubMed
Bowyer, G and Cubitt, S 1995 An improved method of carbon dioxide euthanasia for rodents. Animal Technology 46: 19–28Google Scholar
Britt, DP 1987 The humaneness of carbon dioxide as an agent of euthanasia for laboratory rodents. In: Euthanasia of Unwanted, Injured or Diseased Animals or for Educational or Scientific Purposes pp 19–31. Universities Federation for Animal Welfare: Wheathampstead, Herts, UKGoogle Scholar
Coenen, AM, Drinkenburg, WH, Hoenderken, R and van Luijtelaar, GL 1995 Carbon dioxide euthanasia in rats: oxygen supplementation minimizes signs of agitation and asphyxia. Laboratory Animals 29: 262–268CrossRefGoogle ScholarPubMed
Dahan, A, DeGoede, J, Berkenbosch, A and Olievier, IC 1990 The influence of oxygen on the ventilatory response to carbon dioxide in man. Journal of Physiology 428: 485–499CrossRefGoogle ScholarPubMed
Danneman, PJ, Stein, S and Walshaw, SO 1997 Humane and practical implications of using carbon dioxide mixed with oxygen for anesthesia or euthanasia of rats. Laboratory Animal Science 47: 376–385Google ScholarPubMed
Dawkins, MS 1990 From an animal's point of view: motivation, fitness, and animal welfare. Behavioral and Brain Sciences 13: 1–61CrossRefGoogle Scholar
Duffin, J, Mohan, RM, Vasiliou, P, Stephenson, R and Mahamed, S 2000 A model of the chemoreflex control of breathing in humans: model parameters measurement. Respiration Physiology 120: 13–26CrossRefGoogle Scholar
Golledge, H, Roughan, J, Niel, L, Richardson, C, Wright-Williams, S and Flecknell, P 2005 Carbon dioxide euthanasia in rats - behavioural and autonomic system responses to exposure. Proceedings of the SECAL-ESLAV 2005 International Congress p 40. 5-7 October 2005, Elche, SpainGoogle Scholar
Hackbarth, H, Kuppers, N and Bohnet, W 2000 Euthanasia of rats with carbon dioxide-animal welfare aspects. Laboratory Animals 34: 91–96CrossRefGoogle ScholarPubMed
Hawkins, P, Playle, L, Golledge, H, Leach, M, Banzett, R, Coenen, A, Cooper, J, Danneman, P, Flecknell, P, Kirkden, R, Niel, L and Raj, M 2006 Newcastle Consensus Meeting on Carbon Dioxide Euthanasia of Laboratory Animals. 27-28 February 2006, University of Newcastle upon Tyne, UK. Published online by the NC3Rs (http://www.nc3rs.org.uk/downloaddoc.asp?id=416&page=292&skin=0) and Laboratory Animals Ltd (http://www.lal.org.uk/pdffiles/CO2%20Final%Report.pdf)Google Scholar
Hayashi, F, Yoshida, A, Fukuda, Y and Honda, Y 1983 The ventilatory response to hypoxia in the anesthetized rat. Pflügers Archiv 396: 121–127CrossRefGoogle ScholarPubMed
Hewett, TA, Kovacs, MS, Artwohl, JE and Bennett, BT 1993 A comparison of euthanasia methods in rats, using carbon dioxide in pre-filled and fixed flow rate filled chambers. Laboratory Animal Science 43: 579–582Google Scholar
Hornett, TD and Haynes, AR 1984 Comparison of carbon dioxide/air mixture and nitrogen/air mixture for the euthanasia of rodents. Design of a system for inhalation euthanasia. Animal Technology 35: 93–99Google Scholar
Iwarsson, K and Rehbinder, C 1993 A study of different euthanasia techniques in Guinea pigs, rats, and mice. Animal response and post mortem findings. Scandinavian Journal of Laboratory Animal Science 4: 191–205Google Scholar
Jones, B and Kenward, MG 2003 Design and Analysis of Cross-over Trials, second edition. CRC/Chapman and Hall: Boca Raton, USACrossRefGoogle Scholar
Kohler, I, Meier, R, Busato, A, Neiger-Aeschbacher, G and Schatzmann, U 1999 Is carbon dioxide (CO2) a useful short acting anaesthetic for small laboratory animals? Laboratory Animals 33: 155–161CrossRefGoogle ScholarPubMed
Krohn, TC, Hansen, AK and Dragsted, N 2003 The impact of low levels of carbon dioxide on rats. Laboratory Animals 37: 94–99CrossRefGoogle ScholarPubMed
Leach, MC, Bowell, VA, Allan, TF and Morton, DB 2002a Aversion to gaseous euthanasia agents in rats and mice. Comparative Medicine 52: 249–257Google ScholarPubMed
Leach, MC, Bowell, VA, Allan, TF and Morton, DB 2002b Degrees of aversion shown by rats and mice to different concentrations of inhalational anaesthetics. Veterinary Record 150: 808–815CrossRefGoogle ScholarPubMed
Leach, MC, Bowell, VA, Allan, TF and Morton, DB 2004 Measurement of aversion to determine humane methods of anaesthesia and euthanasia. Animal Welfare 13: S77–S86Google Scholar
Leonard, BE and Rigter, H 1975 Changes in brain monoamine metabolism and carbon dioxide induced amnesia in the rat. Pharmacology, Biochemistry and Behavior 3: 775–780CrossRefGoogle ScholarPubMed
Masuda, A, Ohyabu, Y, Kobayashi, T, Yoshino, C, Sakakibara, Y, Komatsu, T and Honda, Y 2001 Lack of positive interaction between CO2 and hypoxic stimulation for pCO2-VAS response slope in humans. Respiration Physiology 126: 173–181CrossRefGoogle ScholarPubMed
Niel, L and Weary, DM 2006 Behavioural responses of rats to gradual-fill carbon dioxide euthanasia and reduced oxygen concentrations. Applied Animal Behaviour Science 100: 295–308CrossRefGoogle Scholar
Niel, L and Weary, DM 2007 Rats avoid exposure to carbon dioxide and argon. Applied Animal Behaviour Science 107: 100–109CrossRefGoogle Scholar
Niel, L, Stewart, SA and Weary, DM 2008 Effect of flow rate on aversion to gradual-fill carbon dioxide exposure in rats. Applied Animal Behaviour Science 109: 77–84CrossRefGoogle Scholar
Nunn, JF 1987 Applied Respiratory Physiology, 3rd edition. Butterworths: London, UKGoogle Scholar
Olfert, ED, Cross, BM and McWilliam, AA 1993 Guide to the Care and Use of Experimental Animals, Volume 1, 2nd edition. Canadian Council on Animal Care: Ottawa, CanadaGoogle Scholar
Paolino, RM, Quartermain, D and Miller, NE 1966 Different temporal gradients of retrograde amnesia produced by carbon dioxide anesthesia and electroconvulsive shock. Journal of Comparative and Physiological Psychology 62: 270–274CrossRefGoogle ScholarPubMed
Porter, AL 1972 An analytical review of the effects of non-hydrogen-bonding anesthetics on memory processing. Behavioral Biology 7: 167–198CrossRefGoogle ScholarPubMed
Reber, AS 2001 The Penguin Dictionary of Psychology, 3rd edition. Penguin: London, UKGoogle Scholar
Rushen, J 1990 Use of aversion-learning techniques to measure distress in sheep. Applied Animal Behaviour Science 28: 3–14CrossRefGoogle Scholar
Smith, W and Harrap, SB 1997 Behavioural and cardiovascular responses of rats to euthanasia using carbon dioxide gas. Laboratory Animals 31: 337–346CrossRefGoogle ScholarPubMed
Yavari, P, McCulloch, PF and Panneton, WM 1996 Trigeminally-mediated alteration of cardiorespiratory rhythms during nasal application of carbon dioxide in the rat. Journal of the Autonomic Nervous System 61: 195–200CrossRefGoogle ScholarPubMed
Young, A 2006 Halothane induction results in differing behaviours compared with carbon dioxide mixed with oxygen when used as a rat euthanasia agent. Animal Technology and Welfare 5: 49–59Google Scholar