Carbon dioxide for euthanasia: Concerns regarding pain and distress, with special reference to mice and rats

K. M. Conlee, Martin L Stephens, A. N. Rowan, L. A. King

Research output: Contribution to journalArticle

Abstract

Carbon dioxide (CO2) is the most commonly used agent for euthanasia of laboratory rodents, used on an estimated tens of millions of laboratory rodents per year worldwide, yet there is a growing body of evidence indicating that exposure to CO2 causes more than momentary pain and distress in these and other animals. We reviewed the available literature on the use of CO2 for euthanasia (as well as anaesthesia) and also informally canvassed laboratory animal personnel for their opinions regarding this topic. Our review addresses key issues such as CO2 flow rate and final concentration, presence of oxygen, and prefilled chambers (the animal is added to the chamber once a predetermined concentration and flow rate have been reached) versus gradual induction (the animal is put into an empty chamber and the gas agent(s) is gradually introduced at a fixed rate). Internationally, animal research standards specify that any procedure that would cause pain or distress in humans should be assumed to do so in non-human animals as well (Public Health Service 1986, US Department of Agriculture 1997, Organization for Economic Cooperation and Development 2000). European Union guidelines, however, specify a certain threshold of pain or distress, such as 'skilled insertion of a hypodermic needle', as the starting point at which regulation of the use of animals in experimental or other scientific procedures begins (Biotechnology Regulatory Atlas n.d.). There is clear evidence in the human literature that CO2 exposure is painful and distressful, while the non-human literature is equivocal. However, the fact that a number of studies do conclude that CO2 causes pain and distress in animals indicates a need for careful reconsideration of its use. Finally, this review offers recommendations for alternatives to the use of CO2 as a euthanasia agent.

Original languageEnglish (US)
Pages (from-to)137-161
Number of pages25
JournalLaboratory Animals
Volume39
Issue number2
DOIs
StatePublished - Apr 2005
Externally publishedYes

Fingerprint

Euthanasia
euthanasia
distress
Carbon Dioxide
pain
carbon dioxide
Pain
rats
mice
Rodentia
Laboratory Personnel
animals
Pain Threshold
United States Public Health Service
Atlases
laboratory animals
Laboratory Animals
European Union
Biotechnology
Agriculture

Keywords

  • Anaesthesia
  • Carbon dioxide
  • Distress
  • Euthanasia
  • Pain
  • Rodents
  • Welfare

ASJC Scopus subject areas

  • Animal Science and Zoology
  • veterinary(all)

Cite this

Carbon dioxide for euthanasia : Concerns regarding pain and distress, with special reference to mice and rats. / Conlee, K. M.; Stephens, Martin L; Rowan, A. N.; King, L. A.

In: Laboratory Animals, Vol. 39, No. 2, 04.2005, p. 137-161.

Research output: Contribution to journalArticle

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