Journal of the American Association for Laboratory Animal Science最新文献

Euthanasia is the humane termination of an animal's life and an important consideration for scientists, veterinarians, regulators, and others contemplating investigations involving animals. Techniques for euthanasia must induce the most rapid, painless, and distress-free death possible. This study investigated the effectiveness of direct current induction of ventricular fibrillation for the euthanasia of sheep after a primary study in which artifacts or chemical contamination from injectable euthanasia agents were undesirable. Female crossbred adult sheep (Ovis aries; n = 12) under deep isoflurane general anesthesia were instrumented with electrophysiology catheters to induce ventricular fibrillation for euthanasia. Data regarding invasive arterial blood pressure, expired airway gases, limb lead electrocardiograms, and pulse oximetry were collected and assessed just prior to, immediately after, and at 5, 10, 15, and 20min after energy delivery. In all animals, a single 10-s application of 9V of direct current to the right ventricular endocardium via the electrophysiology catheter induced persistent ventricular fibrillation. Arterial blood pressure (mean ± 1 SD) immediately after fibrillation induction was 22.9±4.5mmHg, with negligible difference between systolic and diastolic pressures. The lack of differential pressure continued through the end of the monitoring period. Arterial blood pressure reached an initial nadir at 1??0.5min after fibrillation induction, peaked (40.8±11.1mmHg) due to a vasoconstrictive reflex at 3min after induction, and returned to a static uniform pressure (20.4±17.8mmHg) with mildly increased variability due to reflexive diaphragmatic contractions at 10min after induction. The use of 9V direct current for the induction of ventricular fibrillation via an electrophysiology catheter is a reliable method of euthanasia in sheep.

An essential aspect of animal resource programs is the storage and provision of food for a variety of species. Environmental parameters for feed storage conditions (temperature less than 70 °F; relative humidity less than 50%) are recommended in the Guide for the Care and Use of Laboratory Animals, along with aspects of nutrition such as palatability, vermin-control measures, diet quality, and integrity of feed bags. After receiving a suggestion for improvement for environmental conditions in 2 feed storage locations during an AAALAC accreditation visit, we hypothesized that the packaging of contemporary rodent feed could sustain wider environmental variations in temperature and humidity without adverse impact on integrity and palatability. This study evaluated representative feed storage sites across campus buildings to capture the variation in environmental conditions that are inherent to large and diverse animal care programs. Each test storage location held 2 identical bags of feed (same type, lot, and expiration date) that were stored from June to September of 2021; some aspects of the project were repeated during summer 2022 with a similar rodent feed. Baseline nutrients were analyzed from feed samples collected at time 0 (control) and again after 1 and 3mo of storage. The overall nutritional values measured in feed at the end of the study were not significantly different from control values, regardless of test site and variation in environmental parameters. Retinol (as a measure of Vitamin A) was the only component that decreased significantly; however, final retinol levels were consistently above those necessary for appropriate nutrition for mice. Our animal care program stakeholders were briefed on the outcomes of this study with the intent to verify at future AAALAC site visits that our storage conditions are adequate for maintaining the nutritional quality of packaged rodent feed.

The domestic ferret (Mustela putorius furo) is a common research model for infectious disease and behavioral studies. Ferrets are social animals that are commonly pair-housed. The United States has no species-specific regulatory standards for housing ferrets. Optimal enclosure dimensions have also not been investigated in this species, and cage sizes reported in the literature vary. Adequate space is an important animal welfare consideration, as smaller cages have been linked to increased incidence of stress- or boredom-related behaviors in some species. Here, we evaluated activity budget and space utilization in 2 different enclosure sizes for pair-housed female ferrets (n = 12). Single cages measured 78.7×78.7×45.7cm; double cages were comprised of 2 single cages connected by a short tunnel measuring 17.8 cm. Three pairs of ferrets were housed in each cage size and continuous video recordings were captured for 2 wk prior to crossover to the other cage size. The overall activity budget was similar between groups, with the predominant behavior being inactivity (89%). Stereotypic behaviors, such as cage biting or escape attempts, were infrequent (<0.1%) in both groups. Ferrets in double cages remained in the same cage as their partner 96% of the time, suggesting that social support is very valuable. Our results suggest that ferrets in both cage sizes experienced satisfactory welfare conditions. Our findings also suggest that while cage size is not the only determinant of conspecific aggression, larger cages may be an effective intervention to ameliorate aggression in certain ferrets based on signalment or behavioral history, with particular utility as a potential alternative to re-pairing or single-housing. This study provides valuable information to guide animal care and use programs regarding appropriate ferret housing.

Extended-release (ER) local anesthetics can be used in multi-modal analgesia or in situations in which systemic analgesics may alter animal physiology and thus introduce interpretational confounds. In this study, we compared the analgesic efficacy of an ER buprenorphine formulation with that of a synergistic combination of ER bupivacaine and meloxicam. Female and male CD1 mice were randomly assigned to receive subcutaneous buprenorphine (3.25mg/kg) preemptively, subcutaneous infiltration of bupivacaine???meloxicam (0.03mL at incision closure (bupivacaine, 35mg/kg; meloxicam, 1mg/kg), or saline (10mL/kg SC) after induction of anesthesia. After laparotomy, mice were assessed for changes in daily body weight, rearing frequency, nest consolidation scores, time-to-integrate-nest test (TINT), and response to von Frey testing at 4, 8, 24, 48, and 72h after surgery. Daily weight, nest consolidation scores and rearing frequency were not significantly different among the 3 groups. TINT had fallen significantly response at 24 and 48h after injection in the ER buprenorphine group as compared with the saline and ER bupivacaine-meloxicam groups. Nociceptive thresholds, as assessed with von Frey testing, differed between saline controls and both analgesic groups at 4, 8, 24, 48, and 72 h after surgery. None of the mice in the bupivacaine???meloxicam group developed signs of neurotoxicity, a potential side effect of high-dose local anesthetics. This study demonstrates that local ER bupivacaine???meloxicam may be a useful alternative to systemic, ER buprenorphine for the relief of pain after laparotomy in mice.

Here, we combined the use of 2 technologies that have not previously been used together-a positively pressurized isolator IVC (IsoIVC-P) and a modular isolator with integrated vaporized hydrogen peroxide (VHP) technology???to develop highly tractable and scalable methods to support long-term maintenance of germfree mouse colonies and the concurrent use of germfree and gnotobiotic mice in the same room. This space-efficient system increases the practicality of microbiome studies. Specifically, the exterior surfaces of microbially similar IsoIVC-P were sterilized by using VHP prior to opening the cages and handling the mice therein. This space-efficient system increases the feasibility of microbiome studies. After over 74 wk of experimentation and handling equivalent to more than 1,379,693 germfree mouse-days, we determined that the method and practices we developed have a weekly performance metric of 0.0001 sterility breaks per husbandry unit; this rate is comparable to the isolator 'gold standard.' These data were achieved without adverse incidents while maintaining an Altered Schaedler Flora colony and multiple gnotobiotic studies involving fecal microbial transplants in the same room. Our novel IsoIVC-P???VHP workstation housing system thus improves microbiome research efficiency, eliminates hazards, and reduces risks associated with traditional methods.

This study investigated the induction of anesthesia in swine by injection of tiletamine/zolazepam and ketamine in combination with either dexmedetomidine (TKD) or xylazine (TKX). We hypothesized that TKD would accelerate anesthesia onset and prolong recovery as compared TKX in swine undergoing a noninvasive radiographic procedure. A randomized crossover experiment was performed on 6 healthy, intact, male miniature swine undergoing radiographic examination. Swine were randomly assigned to one of 2 groups: 1) 5mg/kg tiletamine/zolazepam, 2.5mg/kg ketamine, and 0.0125mg/kg dexmedetomidine (TKD) or 2) 5mg/kg tiletamine/zolazepam, 2.5mg/kg ketamine, and 2.5mg/kg xylazine (TKX). Either TKD or TKX was administered intramuscularly at 0.05mL/kg to provide anesthesia for a 45-min radiographic procedure. At 45min after drug administration, atipamezole was administered. During anesthesia, swine were monitored for duration parameters (time to sternal recumbency [onset of anesthesia], lateral recumbency, loss of palpebral reflex, return of the palpebral reflex, and return to sternal recumbency [onset of recovery]) and physiologic parameters (heart rate, %SpO₂, noninvasive blood pressure, and body temperature). Duration and physiologic parameters did not differ between groups at any time point. The results indicate TKD and TKX provide comparable general anesthesia in swine undergoing a radiographic examination.

Immunodeficient mice engrafted with psoriatic human skin are widely used for the preclinical evaluation of new drug candidates. However, the T-cell activity, including the IL23/IL17 pathway, declines in the graft over time after engraftment, which likely affects the study data. Here, we investigated whether the T-cell activity could be sustained in xenografted psoriatic skin by local stimulation of T cells or systemic injection of autologous CD4 + T cells. We surgically transplanted human psoriatic skin from 5 untreated patients onto female NOG mice. Six days after surgery, mice received an intraperitoneal injection of autologous human CD4⁺ T cells, a subcutaneous injection under the grafts of a T-cell stimulation cocktail consisting of recombinant human IL2, human IL23, antihuman CD3, and antihuman CD28, or saline. Mice were euthanized 21 d after surgery and spleens and graft biopsies were collected for analysis. Human T cells were present in the grafts, and 60% of the grafts maintained the psoriatic phenotype. However, neither local T-cell stimulation nor systemic injection of autologous CD4⁺ T cells affected the protein levels of human IL17A, IL22, IFN γ, and TNF α in the grafts. In conclusion, NOG mice seem to accept psoriatic skin grafts, but the 2 approaches studied here did not affect human T-cell activity in the grafts. Therefore, NOG mice do not appear in this regard to be superior to other immunodeficient mice used for psoriasis xenografts.

Euthanasia is frequently performed in amphibians, but techniques are currently limited in number and variable in effectiveness. The current study examined the use of potassium chloride (KCl) for euthanasia of anesthetized African clawed frogs (Xenopus laevis). Twenty adult, female African clawed frogs were anesthetized by immersion in buffered tricaine methanesulfonate (MS-222) for 5 min beyond loss of righting reflex. Frogs were then randomly assigned to receive one of 4 treatments: KCl via intracardiac injection (10 mEq/kg; IC, n = 5), intracoelomic injection (100 mEq/kg; ICe, n = 5), immersion (4,500 mEq/L; IMS, n = 5), or no treatment (C, n = 5). After treatment, serial heart rate was measured via Doppler device until either the loss of Doppler sounds, a 60-min endpoint (IC, ICe, IMS), or recovery (C). Times to loss of righting reflex, loss of Doppler sounds, and/or recovery were recorded. Plasma potassium concentrations were measured immediately after Doppler sound cessation in frogs in IC (n = 1), ICe (n = 2), and IMS (n = 5). Injection failure occurred in 1 IC frog, and 1 Ice frog regained spontaneous movement 4 min after treatment administration. Data from these 2 frogs were not included in statistical analysis. Doppler sound cessation occurred in 4 of 4, 4 of 4, 0 of 5, and 0 of 5 frogs in IC, ICe, IMS, and C, respectively. Median (range) times to Doppler sound cessation in IC and ICe were 6 (0 to 16) s and 18 (10 to 25) min, respectively. Plasma potassium concentration was greater than 9.0 mmol/L in sampled frogs. Intracardiac KCl at 10 mEq/kg and intracoelomic KCl at 100 mEq/kg were effective for euthanasia of anesthetized African clawed frogs. Return to MS-222 solution after KCl administration may be warranted to prevent unintended, premature anesthetic recovery prior to death.