Go to  Advanced Search

Assessment of distress associated with carbon dioxide euthanasia in laboratory rats

Show full item record

Files in this item

Files Size Format Description   View
ubc_2006-200599.pdf 6.849Mb Adobe Portable Document Format   View/Open
 
Title: Assessment of distress associated with carbon dioxide euthanasia in laboratory rats
Author: Niel, Lee Erin
Degree Doctor of Philosophy - PhD
Program Animal Science
Copyright Date: 2006
Abstract: Carbon dioxide (CO₂) gas is the most widely used euthanasia agent for laboratory rodents. However, it has the potential to cause both pain and dyspnea [i.e. dyspnœa], an unpleasant sensation of breathless, while animals are still conscious. The aims of this dissertation were to determine whether gradual-fill CO₂ euthanasia causes distress in laboratory rats, and to examine potential sources of distress, including pain, dyspnea and novelty. The first study examined the behavioural responses of rats during gradual-fill CO₂ euthanasia. Rats showed increased exploratory behaviours and escape behaviours during CO₂ euthanasia, suggesting that this procedure does cause distress. The second and third studies used approach-avoidance testing to investigate aversion to CO₂ in rats, by examining their willingness to enter a test cage containing CO₂ for access to an attractive food reward. Rats were found to avoid CO₂ concentrations that are sufficient to cause unconsciousness. Specifically, when tested with static concentrations of CO₂ rats showed avoidance at 15% CO₂ and greater, and when tested with gradually increasing concentrations of CO₂ at flow rates ranging from 3 to 27% per minute, rats showed avoidance at 13 to 16% CO₂. This avoidance indicates that rats are at least moderately averse to CO₂ concentrations occurring during gradual-fill CO₂ euthanasia, and that forced exposure likely causes distress. Concentrations of CO₂ that were associated with behavioural responses and aversion were not consistent with previous data on pain due to CO₂. However, similar concentrations have been shown to cause dyspnea in humans. The final study examined the role of novelty in rats’ responses to CO₂, and found that novelty was not a major source of distress during gradual-fill CO₂ euthanasia. In summary, these studies suggest that gradual-fill CO₂ euthanasia causes distress in rats, and that this distress is likely due to dyspnea. Further research is necessary to examine the effects of CO₂ on other rodent species such as mice, and to identify alternative methods of euthanasia that cause unconsciousness without distress.
URI: http://hdl.handle.net/2429/18614
Series/Report no. UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/]

This item appears in the following Collection(s)

Show full item record

All items in cIRcle are protected by copyright, with all rights reserved.

UBC Library
1961 East Mall
Vancouver, B.C.
Canada V6T 1Z1
Tel: 604-822-6375
Fax: 604-822-3893