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A Comparison of Ketamine or Etomidate Combined with Xylazine for Intraperitoneal Anesthesia in Four Mouse Strains
Journal article   Open access   Peer reviewed

A Comparison of Ketamine or Etomidate Combined with Xylazine for Intraperitoneal Anesthesia in Four Mouse Strains

Crystal H Gergye, Yixuan Zhao, Reneé H Moore and Vanessa K Lee
Journal of the American Association for Laboratory Animal Science, v 59(5), pp 519-530
01 Sep 2020
PMID: 32723425
url
https://doi.org/10.30802/AALAS-JAALAS-19-000129View
Published, Version of Record (VoR)Open Access (License Unspecified) Open

Abstract

Anesthesia
Intraperitoneal (IP) injection is a common route of anesthetic administration in mice. Ketamine-xylazine (KX) anesthesia is one of the most widely used IP protocols, but has limitations. Etomidate is an alternative to ketamine that has been used in both human and veterinary medicine yet has not been widely studied in mice. The purpose of this study was to evaluate etomidate-xylazine (EX) anesthesia as an alternative to KX. We hypothesized that EX would be as safe and effective as KX, with both sex- and strain-dependent differences. Male and female Crl:CD1(ICR), C57BL/6NCrl, BALB/cJ and NU/J mice were given a single IP dose of ketamine 100 mg/kg and xylazine 10 mg/kg or etomidate 20 mg/kg and xylazine 10 mg/kg. Sedation times were similar between KX and EX, with CD1 mice exhibiting shorter sedation times. Surgical anesthesia was achieved in 44% of EX mice, compared with 4% of KX mice. C57BL/6NCrl mice were significantly more likely to achieve surgical anesthesia when given EX (94%) or KX (18%) than were other strains. In all strains except C57BL/6NCrl mice, females were more likely to reach surgical anesthesia than males. Several mice experienced an adverse hyperexcitement response during induction, with BALB/cJ (79%) and NU/J (87%) mice given EX significantly more likely than other strains to experience hyperexcitement. EX and KX protocols had no overall differences in lowest respiration rate, lowest systolic blood pressure, lowest rectal temperature, or levels of acidosis, although the lowest heart rates were significantly higher with EX, indicating that EX and KX have similar safety profiles. Thus, EX and KX administration were associated with several significant physiologic differences when comparing sexes or individual strains. Our results indicate that EX is an equally effective sedative and a more effective surgical anesthetic than KX; however, EX is only recommended for invasive procedures in C57BL/6 mice due to the high rate of hyperexcitement and inconsistent surgical depth seen in other strains. Further study is needed to optimize EX for use in multiple mouse strains.

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Web of Science research areas
Veterinary Sciences
Zoology
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