Review of Rodent Euthanasia Methods.

The optimal choice of euthanasia method for laboratory rodents depends on a number of factors, including the scientific goals of the study, the need to minimize animal pain and/or distress, applicable guidelines and laws, the training and proficiency of personnel, and the safety and emotional needs of the personnel performing the euthanasia. This manuscript aims to provide guidance to researchers so they may select the method of euthanasia that results in minimal experimental confounds, such as the creation of artifact and alteration of tissues and analytes. Specific situations addressed include euthanasia of large numbers of rodents and euthanasia of neonates. Recent literature supports the notion of significant strain-dependent differences in response to euthanasia methods such as CO2 inhalation. To assist researchers in selecting a strain-appropriate method of euthanasia, the authors present a summary of methodologies for assessing the effectiveness of euthanasia techniques, including elements and parameters for a scoring rubric to assess them.

Comparison of subcutaneous and intramuscular ketamine-medetomidine with and without reversal by atipamezole in Dutch belted rabbits (Oryctolagus cuniculus).

Forty male Dutch belted rabbits (Oryctolagus cuniculus) enrolled in a minimally invasive pharmacokinetics study were used to compare the efficacy of an anesthetic combination delivered through 2 injection routes. Rabbits were randomly assigned to 4 groups (n = 10/group) to determine the sedative and physiologic effects of ketamine (25 mg/kg)-medetomidine (0.5 mg/kg) given either intramuscularly (IM) or subcutaneously (SC). Palpebral, pedal, ear pinch, and righting reflexes, as well as cardiopulmonary parameters (heart rate, respiratory rate, and arterial blood oxyhemoglobin saturation), were recorded every 5 min. In addition, the reversal effects of an intravenous dose of atipamezole (1 mg/kg), an alpha 2 adrenoreceptor antagonist, were assessed by comparing the return of the righting reflex in rabbits given the reversal agent with those that recovered spontaneously. Compared with the IM route, SC ketamine-medetomidine effectively induced chemical restraint with less than a 2-min difference in onset of anesthesia and markedly less resistance (for example, fl inching, kicking, and so forth) during the injection. In all groups, the anesthetic regimen, regardless of the route of administration, provided an adequate level of anesthesia. Reversal with atipamezole improved arterial hemoglobin oxygen saturation for both the SC and IM groups; however, an enhanced rate of recovery from anesthesia was clinically apparent only for animals given the combination by the IM route.