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

Vibration is inherent in research animal facilities due to the mechanical systems and practices required for animal care and use. Ample evidence indicates that vibration can change behavior and physiology in multiple species, potentially altering the results of research studies. Although one cannot eliminate environmental vibration, its control is important in research animal environments to decrease the possibility of introducing a research variable due to vibration effects. To assess the potential for a vibration source to alter experimental results and variability, one must understand the principles of vibration, its likely sources, and control methods. The literature regarding the effects of vibration, as it applies in a practical sense, can be challenging to interpret because the vibration frequencies tested to date have often not been within or near the most sensitive ranges of the species being tested. Some previous studies have used unrealistic vibration magnitudes and provided insufficient detail to duplicate or build upon conclusions. Standardization is essential for research examining the effects of vibration on animals to validate knowledge of this extrinsic variable in animal research and identify ways to mitigate the variable in research facilities.

Guinea pigs are often used in translational research, but providing them with safe and effective anesthesia is a challenge. Common methods like inhalant anesthesia and injectable ketamine/xylazine induce surgical anesthesia but can negatively affect cardiovascular, respiratory, and thermoregulatory systems and complicate the interpretation of research outcomes. Several alternative anesthetic regimens have been investigated, but none have consistently achieved a surgical plane of anesthesia. Therefore, identifying an anesthetic regimen that achieves a stable state of the surgical plane of anesthesia while preserving cardiorespiratory function would be a valuable contribution. To address this issue, we compared the efficacy of 3 anesthetic combinations in female Dunkin-Hartley guinea pigs: 1) alfaxalone, dexmedetomidine, and fentanyl (ADF); 2) alfaxalone, midazolam, and fentanyl (AMF); and 3) alfaxalone, midazolam, fentanyl, and isoflurane (AMFIso). We monitored anesthetic depth, heart rate, oxygenation, respiratory rate, respiratory effort, blood pressure, and body temperature every 15 min from injection to recovery. We also recorded the time to loss of righting reflex, duration of anesthesia, and time to achieve a surgical plane. The results showed no statistically significant differences in induction and recovery times among the groups. In the AMFIso group, 100% of the animals achieved a surgical plane of anesthesia, whereas only 10% of the animals in the AMF group reached that level. None of the animals in ADF group reached a surgical plane of anesthesia. Respiratory rate was significantly lower in the AMFIso as compared with the ADF group (P < 0.001) but was not different between the AMF and ADF groups. Temperature was significantly lower in the AMFIso group as compared with both the ADF and AMF groups (P < 0.001). In conclusion, both combinations of solely injectable anesthetics assessed in this study can be used for short, nonpainful procedures without significant cardiorespiratory depression. However, for mildly to moderately painful surgical procedures, the addition of an inhalant anesthetic like isoflurane is necessary for female guinea pigs.

Perinatal mortality is a common problem in mouse breeding colonies. Few studies have examined the influence of environmental changes on mouse pup survival. In this study, monogamous breeding cages of C57BL/6J mice were set up and randomized into 3 cage change groups: 1) cage change at 8 d after parturition, 2) cage change at 3 d after parturition, or 3) cage change at 3 d after parturition with the addition of a polycarbonate hut in the cage. Pairs were bred to produce a minimum of 4 litters. Pup survival to weaning relative to experimental cage change date, and survival rates after cage change were evaluated. The results revealed no significant differences between experimental groups. The majority of pup loss occurred within the first 24 h after birth for those pups that were alive at birth. Overall, the postpartum day of cage change did not affect the perinatal survival of mouse pups.

Guinea pigs (Cavia porcellus) are a commonly used species in biomedical research. As social creatures, compatible guinea pigs should be housed together unless scientific objectives or veterinary care require otherwise. Extensive literature suggests that adult male guinea pigs are highly aggressive in the presence of females, but data are lacking regarding the compatibility of cohoused adult males in the absence of females. Most studies that use adult males do not report housing densities. We used serial wound scoring and observations of behavior to determine whether unfamiliar adult male guinea pigs will develop stable, prosocial isosexual pairs. Wound scoring was performed before and 24 h after pairing. Serial behavioral observations assessed affiliative and agonistic behaviors at 0.5, 2, 24, and 48 h after pairing. Wound scoring and behavioral observations continued weekly for 1 mo and monthly thereafter. Wound scores were significantly higher at 24 h after pairing as compared with baseline and all other time points. Wounding was rare after week 2, indicating reduced aggression. Furthermore, affiliative behaviors significantly increased over time while agonistic behaviors were rare. Together, these data suggest that unfamiliar adult male guinea pigs establish stable prosocial pairs after an acclimation period. As was done in the present study, providing ample space, separate shelters for each animal, and the absence of female guinea pigs will likely facilitate successful pairing. We recommend consideration of a social housing program for adult male guinea pigs to provide companionship and enrich their housing environment.

The effects of commonly used injectable combinations of anesthetics such as ketamine and xylazine, with or without acepromazine, vary widely across individuals, have a shallow-dose response curve, and do not provide long-term analgesia. These drawbacks indicate the importance of continuing efforts to develop safe and effective injectable anesthetic combinations for mice. In this study, a series of experiments was designed to validate the use of dexmedetomidine and midazolam to provide chemical restraint for nonpainful procedures and the addition of buprenorphine or extended-release buprenorphine to reliably provide a surgical plane of anesthesia in C57BL/6J mice. Loss of consciousness was defined as the loss of the righting reflex (LORR); a surgical plane of anesthesia was defined as the LORR and loss of pedal withdrawal after application of a 300 g noxious stimulus to a hind paw. The combination of intraperitoneal 0.25 mg/kg dexmedetomidine and 6 mg/kg midazolam produced LORR, sufficient for nonpainful or noninvasive procedures, without achieving a surgical plane in 19 of 20 mice tested. With the addition of subcutaneous 0.1 mg/kg buprenorphine or 1 mg/kg buprenorphine-ER, 29 of 30 mice achieved a surgical plane of anesthesia. The safety and efficacy of the regimen was then tested by successfully performing a laparotomy in 6 mice. No deaths occurred in any trial, and, when administered 1 mg/kg atipamezole IP, all mice recovered their righting reflex within 11 min. The anesthetic regimen developed in this study is safe, is reversible, and includes analgesics that previous studies have shown provide analgesia beyond the immediate postsurgical period. Buprenorphine-ER can be safely substituted for buprenorphine for longer-lasting analgesia.

Although the Guide suggests changing rodent cage components every 2 wk, it states that "decreased sanitation frequency may be justified if the microenvironment in the cages, under the condition of use ..., is not compromised." The purpose of this study was to evaluate extended sanitation intervals of cage components (automated watering valve, wire bar lid, and filter top) of mouse individually ventilated caging (IVCs) at our institution. We hypothesized that there would be no significant difference in relative light units measured by ATP luminometry of these cage components at the control time point of 14 d as compared with each extended time interval: 28, 56, and 84 d. In addition, for automated watering valves, the study was extended to 168 d. We also hypothesized that time-and-motion studies performed by moving to a sanitation interval of 84 d for all components would result in substantial time and cost savings. The components of a total of 24 cages containing 4 or 5 mice each were swabbed, and an ATP luminometer was used to detect organic matter. We found no significant differences in organic matter load between 14 d and all other time points for all cage components. Our time- and cost-savings analysis found that extending the sanitation interval of cage components from every 2 wk (14 d) to every 3 mo (84 d) for every 10,000 cages would save about 3,000 technician hours annually, for a total annual labor cost savings of about $100,000. This study is the first to validate the extended sanitation interval of automated watering valves and confirms the findings of previous studies that validated the extended sanitation frequency of wire bar lids and filter tops of rodent IVCs. Overall, extending the sanitation frequency of cage components reduces workload of animal care staff without compromising the cage microenvironment.