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Laferriere CA, Leung VSY, Rousseau-Blass F, Lalonde-Robert V, Pang DSJ. Intrahepatic Injection of Sodium Pentobarbital as an Alternative to Intraperitoneal Injection for the Euthanasia of Rats ( Rattus norvegicus). JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2022; 61:201-207. [PMID: 35063046 PMCID: PMC8956212 DOI: 10.30802/aalas-jaalas-21-000094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 03/22/2021] [Accepted: 04/07/2021] [Indexed: 06/14/2023]
Abstract
The most commonly accepted method of rat euthanasia in North America is intraperitoneal injection of sodium pentobarbital (PB). However, misinjection can occur, and intraperitoneal PB may cause pain and distress. The objective of this study was to test an alternative method of euthanasia: intrahepatic injection of PB. A pilot study was conducted to develop a method of intrahepatic injections (evaluated using CT scans and test injections), followed by a full study comparing intraperitoneal (n = 14) and intrahepatic PB injections (n = 66) in adult rats. Full study outcomes were: 1) time from injection to loss of right- ing reflex (LORR), 2) time from injection to cessation of heartbeat (CHB), 3) number of failed euthanasia attempts, and 4) confirmation of successful intrahepatic injection or misinjection via necropsy. All injections were performed by a veterinary student. CT revealed that intrahepatic injections were feasible. Times (median [range]) to LORR and CHB were faster after successful intrahepatic injections (LORR, 3 s [1 to 5 s]; CHB, 8 s [2 to 242 s]) than after intraperitoneal injections (LORR, 89.5 s [73 to 110 s], CHB: 284.5 s [237 to 423 s]). The misinjection rate was higher with intrahepatic injections (59%) than with intraperitoneal injections (29%), but intrahepatic misinjection still resulted in fast and successful euthanasia (LORR, 29 s [1 to 96 s]; CHB, 216 s [12 to 330 s]), with the injectate distributed between the intraperitoneal and intrahepatic locations. The number of failed euthanasia attempts with intrahepatic injections was low (n = 2). Intrahepatic injections show potential as an alternative to intraperitoneal injections for rat euthanasia.
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Affiliation(s)
- Colin A Laferriere
- Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | - Vivian SY Leung
- Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | - Frédérik Rousseau-Blass
- Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Québec, Canada
| | - Vanessa Lalonde-Robert
- Research Models and Services, Charles River Laboratories, Saint-Constant, Québec, Canada; and
| | - Daniel SJ Pang
- Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Québec, Canada
- Veterinary Clinical and Diagnostic Sciences, University of Calgary Faculty of Veterinary Medicine, Alberta, Canada
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Reimer JN, Schuster CJ, Knight CG, Pang DSJ, Leung VSY. Intraperitoneal injection of sodium pentobarbital has the potential to elicit pain in adult rats (Rattus norvegicus). PLoS One 2020; 15:e0238123. [PMID: 32881944 PMCID: PMC7470368 DOI: 10.1371/journal.pone.0238123] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 08/10/2020] [Indexed: 12/17/2022] Open
Abstract
An effective and pain-free killing method is required to achieve the goal of euthanasia, a "good death". Overdose of sodium pentobarbital (PB) by intraperitoneal (IP) injection is a widely accepted technique in laboratory rats, but questions remain regarding pain associated with administration. As PB rapidly causes sedation and loss of consciousness, most studies have relied on indirect evidence of pain. The objective of this study was to assess pain associated with IP PB using an appropriate vehicle control. Adult male and female Sprague Dawley (SD) and female Wistar rats (N = 84) were block randomised by sex and strain to receive one of three treatments: 1) 800 mg/kg PB (pH 11), 2) saline or 3) vehicle controls (pH 11 or 12.5). Behavior (Rat Grimace Scale (RGS), writhing, back arching) was evaluated at baseline, before loss of righting reflex (LORR, PB group), and at 80s, 151s and 10 min post-injection (PI; saline and vehicle control groups). In the PB group, mean time to LORR was 78 ± 7.9 seconds. In the vehicle control groups, RGS scores were increased at 151s PI (SD: p = 0.0002, 95%CI 0.73 to 0.20) from baseline, as was relative frequency of writhing (SD: p < 0.0001; Wistar; p = 0.0004). RGS scores remained elevated 10 mins PI (SD: p = 0.0005, 95%CI 0.71 to 0.18; Wistar: p = 0.0234, 95%CI 0.91 to 0.07) but the relative frequency of writhing did not (p > 0.999). The RGS scores and the relative frequency of writhing remained low in the PB and saline groups (p > 0.05). These results show that, vehicle controls for IP PB result in signs associated with pain, pain may not be experienced following IP PB when LORR occurs quickly, and that the effects of PB limit behavioral pain assessments.
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Affiliation(s)
- J. N. Reimer
- Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - C. J. Schuster
- Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - C. G. Knight
- Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - D. S. J. Pang
- Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC, Canada
- Groupe de Recherche de Pharmacologie Animale du Québec (GREPAQ), Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC, Canada
| | - V. S. Y. Leung
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC, Canada
- Groupe de Recherche de Pharmacologie Animale du Québec (GREPAQ), Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC, Canada
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Laferriere CA, Pang DS. Review of Intraperitoneal Injection of Sodium Pentobarbital as a Method of Euthanasia in Laboratory Rodents. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2020; 59:254-263. [PMID: 32156325 PMCID: PMC7210732 DOI: 10.30802/aalas-jaalas-19-000081] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 07/17/2019] [Accepted: 09/23/2019] [Indexed: 12/26/2022]
Abstract
Euthanasia is one of the most commonly performed procedures in biomedical research, involving tens of millions of animals in North America and Europe every year. The use of sodium pentobarbital, injected intraperitoneally, for killing rodents is described as an acceptable technique by the AVMA and CCAC euthanasia guidelines. This drug and route are recommended over inhalant anesthetics, carbon dioxide, and physical methods for ethical and aesthetic reasons as well as efficiency. However, a growing body of evidence challenges the efficacy and utility of intraperitoneal pentobarbital. This methodology has been described as inconsistent and may induce pain and stress. With these considerations in mind, a review of the literature is needed to assess the evidence surrounding this killing method, the associated welfare implications, and potential for refinement.
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Affiliation(s)
- Colin A Laferriere
- Clinical Sciences, Faculty of Veterinary Medicine, University of Montreal, Saint- Hyacinthe, Québec, Canada
| | - Daniel Sj Pang
- Veterinary Clinical and Diagnostic Sciences, University of Calgary, Calgary, Alberta, Canada;,
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