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

Evidence showing a relationship between the mouse gut microbiome and properties such as phenotype and reaction to therapeutic agents and other treatments has increased significantly over the past 20 to 30 y. Recent concerns regarding the reproducibility of animal experiments have underscored the importance of understanding this relationship and how differences in husbandry practices can affect the gut microbiome. The current study focuses on effects of different barrier practices in 2 barrier facilities at the same institution on the fecal microbiome of breeding C57Bl/6J mice. Ten female and 10 male C57Bl/6J mice were obtained in one shipment from Jackson Laboratories and were housed under different barrier conditions upon arrival. Fecal samples were collected on arrival and periodically thereafter and were sent to TransnetYX for microbiome analysis. Mice used for collection of feces were housed as breeding pairs, with a total of 5 breeding pairs per barrier. An additional fecal sample was collected from these mice at 8 wk after arrival. One F1 female and one F1 male from each breeding cage were housed as brother-sister breeding pairs and a fecal sample was collected from them at 8 wk of age. Brother-sister breeding colonies were continued through F3, with fecal samples for microbiome analysis were collected from each generation at 8 wk of age. Breeding colonies in the 2 barriers showed differences in relative abundance, α -diversity, and β -diversity. Our data indicate that differences in barrier husbandry practices, including the use of autoclaved cages, the degree of restricted access, feed treatment practices, and water provision practices, can affect fecal microbiome divergence in both the parental and filial generations of different breeding colonies. To our knowledge, this is the first study to examine the effect of barrier husbandry practices on the microbiome of breeding colonies through the F3 generation.

Myocoptes musculinus is a common ectoparasite of wild mice and is occasionally found on research mice. Infestations of research mice are often subclinical but can cause severe dermatitis. Perhaps more importantly, infestations can cause immunologic reactions that may alter research outcomes, and most animal research facilities strive to prevent or eliminate mites from their mouse colonies. M. musculinus infestations are currently detected by using microscopic evaluation of the fur and skin and PCR assays of pelt swabs targeting the rRNA genes of this mite. In our facility, we encountered multiple, false-positive 18S rRNA PCR results from a closed mouse colony. We could not identify the source of the false positives even after performing PCR analysis of other Myocoptes gene targets using assays developed from the few other target genomic sequences available for M. musculinus or Myocoptes japonensis in public databases. This situation highlighted the limited genetic resources available for development of diagnostic tests specific for this ectoparasite. To expand the available genetic resources, we generated a metagenome of M. musculinus derived by sequencing from fur plucks of an infected mouse. We also determined the completeness of this metagenome and compared it with those of related mites.

Changes in housing density, including individual housing, are commonly necessary in animal research. Obtaining reproducibility and translational validity in biomedical research requires an understanding of how animals adapt to changes in housing density. Existing literature mainly addresses acclimatization after transportation. We used a within-subject design to examine changes in behavior and weight gain of 4-mo-old male Wistar Han rats after reduction of their social group (RSG; due to removal of one rat from a cage containing 3 rats) and social isolation (SI; the removed rat) for the subsequent 2 wk. Changes in weight gain and in exploratory and center-avoidance behavior in an inescapable open arena (OA) were measured before (D0) and on days 7 and 14 (D7 and D14, respectively) after social change. The motor response to d-amphetamine (1.5 mg/kg), which stimulates behavioral arousal in response to novelty, was assessed at D14. Within-subject design revealed that RSG rats in OA had less locomotion at D7 but not more center-avoidance behavior and had returned to the D0 activity level at D14; SI rats in OA had consistently less locomotion and more center-avoidance behavior. Rearing behavior during OA exposure did not change in either group. However, SI rats showed more center-avoidance behavior in OA, greater weight gain, and less amphetamine-induced rearing at D14 as compared with RSG rats. These data indicate that after RSG, mature adult male rats require 2 wk to return to their baseline level of OA-related behavior, while after SI they gain weight and acquire maladaptive exploratory and center-avoidance behavior. The finding that SI produces maladaptive behavioral and physiologic alterations in adult male rats deserves attention because these changes could have confounding effects on research findings.

Expanding the use of methods that refine, reduce, and replace (3Rs) the use of animals in research is fundamental for both ethical and scientific reasons. The mission of the 3Rs Translational and Predictive Sciences Leadership Group (3Rs TPS LG) of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ Consortium) is to promote sharing and integration of science and technology to advance the 3Rs in the discovery and development of new medicines, vaccines, medical devices, and health care products for humans and animals. The 3Rs TPS LG is dedicated to identifying opportunities for member companies to share practices, enhance learning, promote discussions, and advance the 3Rs across the industry. One such opportunity was a benchmarking survey, conducted by the Contract Research Organization (CRO) Outreach Working Group, designed to share practices in rodent husbandry for drug safety research and to identify potential opportunities for refinement. IQ member companies and CROs in Asia, North America, and Europe were surveyed. Areas identified for potential alignment included provision of corncob bedding and wire-grid flooring, management of the nest at cage change, approaches to social housing for male mice, evidence-based enrichment strategies, and evaluating the effects of the timing of studies in relation to the animals' circadian rhythm and light-cycle, with consideration for how such extrinsic factors influence animal welfare and scientific outcomes. This manuscript presents the results of the benchmarking survey, including general trends in mouse and rat husbandry practices in toxicology studies, considerations for social housing, enrichment selection, and potential effects of bedding substrate, emphasizing opportunities for collaboration that can help to identify refinements to rodent husbandry practices.

Ensuring asepsis of the surgical site before surgery is an essential component of safe surgical practices to reduce the incidence of surgical site infections in veterinary medicine. The current accepted method of skin preparation is a multistep process that alternates either a povidone-iodine or chlorhexidine soap scrub with a 70% alcohol rinse. After cleansing, the site is left to dry before draping. The goal of this study was to assess the effectiveness of a waterless alcohol-based (WAB) antiseptic as part of a 2-step procedure after the soap scrub. WAB antiseptics are commonly used as a presurgical hand scrub for the surgeon as they evaporate quickly and provide effective antisepsis. Previous studies have examined the WAB antiseptics in small animal surgeries. We tested this approach in large animal surgery. Twenty-four rhesus macaques were divided into 4 groups that received one of the following treatments: saline and alcohol, iodine-alcohol-iodine, soap scrub/WAB, and chlorhexidine-alcohol-chlorhexidine. The surgical site was swabbed before and after treatment and plated to assess sterility. Overall, no colonies were recovered from skin treated with WAB antiseptic, establishing it as an effective alternative to the current standard protocol. This method will simplify the current 3-step procedure and reduce animal handling, the use of materials, and the time necessary for surgical preparation.

Rabbits are especially susceptible to adverse effects related to surgery, which can lead to inappetence and gastrointestinal (GI) stasis. However, these adverse effects may be related to discomfort from the procedure, anesthesia, the analgesics used, and the stress of restraint for analgesic administration. Opioid and NSAID analgesics which are frequently used in rabbits, can contribute to these adverse effects. This study compared the clinical GI side effects of buprenorphine and carprofen to saline controls in New Zealand White rabbits after a nonsurgical anesthetic event. Nine rabbits (3 females and 6 males, aged 8 to 20 mo) were randomly rotated through 5 treatment groups with a 7-d washout period between treatments: anesthesia control (no treatment), buprenorphine (0.05 mg/kg SC every 12 h for 72 h), carprofen (5 mg/kg SC every 24 h for 72 h), twice daily saline control (equivalent volume to buprenorphine SC every 12 h for 72 h), and once daily saline control (equivalent volume to carprofen SC every 24 h for 72 h). All rabbits were anesthetized 5 times and received initial treatments on the day of anesthesia. Generalized linear mixed models were used to assess food intake, water intake, and fecal output score for 7 days after anesthesia. Analysis showed that buprenorphine-treated rabbits had a significant 4-d decrease in food intake and a 3-d decrease in fecal output score compared with baseline. None of the other treatment groups showed any changes in food intake or fecal output score compared with baseline. These findings demonstrate that in the absence of pain, buprenorphine significantly depresses food intake in rabbits and that restraint and injections have minimal effect on food intake despite the possibility of increased stress.

Appropriate analgesia is a crucial part of rodent postoperative and postprocedural pain. Providing appropriate analgesia is an ethical obligation, a regulatory requirement, and an essential element of obtaining quality scientific results and conducting reproducible data. Meeting these requirements is facilitated by practical, efficient and safe delivery methods for providing analgesia. Over the last decade, long-acting analgesics have gained widespread use in research animal medicine to avoid or treat postoperative or postprocedural pain while minimizing handling-related time and stress. Long-acting formulations of analgesics suitable for rodents are available for opioids, NSAIDs, and local anesthetics. The goal of this review is to summarize the currently available long-acting formulations of analgesics for rodents and to provide recommendations to veterinarians and researchers regarding their use.

Floor cleaning and disinfection are essential components of maintaining animal health status and meeting regulatory requirements in research vivaria. However, best practices for method, frequency, and evaluation techniques have not been established. Reuse of cotton string mop and bucket systems has been implicated in spreading contamination in the human hospital setting. We evaluated 4 different combinations of disinfectant and mop systems commonly used in rodent vivaria. Eight housing rooms were mopped a total of 4 times using one of the following methods: quaternary ammonium compound (QUAT) and cotton string mop (QC), QUAT and microfiber mop (QM), hydrogen peroxide disinfectant (HPD) and cotton string mop (HC), or HPD and microfiber mop (HM). ATP and RODAC samples of the floor were taken before and after mopping. The time to mop each room, floor drying time, and the amount of disinfectant used were recorded. The QC method was associated with significantly more bacterial contamination while all other methods significantly reduced bacterial contamination. The QC method performed significantly worse in reducing bacterial contamination as compared with all other methods when cotton mop heads were reused. All methods except QC significantly reduced ATP levels, with the HC and HM methods being significantly more effective at reducing ATP levels than the QC and QM methods. Costs were similar for the QC, QM, and HM methods. The results of this study indicate that reuse of cotton string mop heads with QUAT increases floor contamination while HPD is effective for up to 3 reuses. Single use microfiber mops were effective with both QUAT and HPD but did not result in more effective cleaning or disinfection than cotton string mops.

Differences in cage microenvironments may contribute to variation in data and affect the outcome of animal studies involving metabolic diseases. To study this, we compared the effects 3 types of bedding-corncob bedding, hardwood bedding, and hardwood bedding plus a cardboard enrichment item-on baseline fasting and nonfasting blood glucose and body weight in mice. Mice housed on corncob bedding showed significantly higher fasting blood glucose than did mice housed on hardwood bedding, with or without the enrichment item. None of the groups showed an effect of bedding type on nonfasting blood glucose levels or body weight. This information informs the choice of bedding substrates for studies that measure fasting blood glucose and potentially mitigates a variable that could confound research outcomes.

Maximizing operational efficiency while maintaining appropriate animal housing conditions is a continuous focus of research animal care programs. Our institution's longstanding approach to cage-change management included scheduled cage changes every 2 wk, with spot changes if cages met established visual criteria during the intervening period. This 2-wk plus spot changing (2WS) practice for mice housed in IVC was problematic during the COVID-19 pandemic when the need arose to minimize workload to reduce on-site staffing out of concern for employee health and possible absenteeism. With the approval of the IACUC, a spot-change-only (SCO) process was adopted, with the requirement to evaluate microenvironmental parameters under both practices to confirm acceptable equivalence. These parameters (humidity, temperature, and ammonia) were evaluated in a controlled study that found no significant difference between the 2 groups. Ammonia levels did not exceed 10 ppm in any group throughout the study. To assess operational differences between these 2 approaches, we collected cage-change data and employee feedback from facilities operating under these schemes. The SCO method required fewer cage changes than did the 2WS method (10.3% per day with 2WS and 8.4% per day with SCO). Despite this benefit, through a Plan-Do-Check-Act process that has been regularly employed at our institution, employee feedback identified important operational challenges associated with the SCO practice. The SCO approach was thus refined into a scheduled spot change (SSC) practice that builds on the SCO model by incorporating a scheduled focused cage evaluation period. Based on subsequent feedback, the SSC was found to retain the efficiency benefits afforded by the SCO model and simultaneously alleviated staff and operational concerns. This result underscores the importance of integrating staff feedback with a performance standard-based approach when assessing cage-change management.