Pang, Daniel SJMerenick, Dexter Reece2024-04-232024-04-232024-04-22Merenick, D. R. (2024). Assessing carbon dioxide euthanasia in laboratory rodents (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/118472https://doi.org/10.11575/PRISM/43314Overdose of carbon dioxide gas (CO2) is a commonly performed euthanasia method for rodents; however, CO2 exposure activates nociceptors in rats and is reported to be painful in humans at concentrations equal or greater than 32.5%. In rats, it is unclear if unconsciousness following CO2 exposure occurs at concentrations below that associated with pain. A standardized loss of righting reflex (LORR) method was applied to identify CO2 concentrations associated with unconsciousness in rats. Additionally, a systematic review examined the consistency and completeness of LORR methods reported in the literature. The results from this thesis show that: 1) strain differences exist in the CO2 concentration required to induce LORR, 2) different LORR assessments can affect the results obtained, and 3) substantial inconsistencies in LORR methodology reporting exist in the literature. These findings raise awareness of strain-specific susceptibilities to CO2 exposure indicating that rat strains have different likelihoods of experiencing nociception and pain. In addition, this research identified longstanding persistent problems in the reporting of LORR methodology. In conclusion, the results from this thesis emphasize potential refinements to CO2 euthanasia and LORR methodological reporting.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Veterinary Sciencemaster thesis