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

Escherichia coli strains are the most common bacterial cause of canine neonatal mortality, with rectal and vaginal contaminants from the mother reportedly serving as an important source of infection. Between July and September 2013, a canine research facility at Michigan State University experienced a spike in neonatal mortality. Thirteen of 14 puppies from 2 litters died, with 10 being submitted for necropsy. Three puppies from one litter struggled since birth to suckle and died. Five puppies from an additional litter died after presenting due to failure to thrive, depression, and lethargy. All puppies exhibited microscopic lesions consistent with septicemia represented by interstitial necrotizing pneumonia, random hepatocellular necrosis, or intravascular bacteria. Bacterial cultures of the lung and liver yielded numerous β-hemolytic Streptococcus group G and numerous Escherichia coli, which tested positive by PCR for the cytotoxic necrotizing factor 1 (cnf1) gene. Vaginal and rectal culture swabs taken from adult breeding females between 2013 and 2020 revealed that many were asymptomatic carriers of cnf1+ E. coli. The institution of prophylactic antimicrobial treatment for pregnant females testing culture positive for cnf1+ E. coli before parturition may have prevented additional puppy losses; however, it may have also contributed to resistance observed in future samples. While increased attention to pregnant females testing positive for cnf1+ E. coli prevented subsequent neonatal mortality, the source of the pathogen was not identified. More in-depth sampling of the facility environment could identify a reservoir; however, endemic carriers cannot be ruled out. Screening protocols may be warranted in facilities experiencing persistent cnf1+ E. coli infections.

Group or pair housing of social animals in laboratory settings is beneficial to animal welfare. Social housing of male mice can be difficult due to possible aggressive behaviors, leading to injury and resulting in animals not being able to continue in the study. Techniques used to decrease male mouse aggression and territorial behaviors have been described in recent literature, including pairing mice before sexual maturity, moving used nesting material over during cage changes, removing high-value items that can encourage territorial behaviors, and using low-stress handling techniques. Using these suggested tactics, we conducted a 28-day study determining the social compatibility of male CD-1 mice in a standard toxicological study design. Forty-eight mice, aged 5 weeks old, were equally divided into single and pair housing and were administered theophylline daily. Animals were exposed to common toxicology study procedures known to cause additional stress including repeated blood collections, daily dosing, weekly clinical observations and body weights, and terminal urine collections. Behavioral assays, including nest scores and time-to-integrate-nest-material testing, were performed weekly, and pelt scores were collected postmortem. Fecal samples were collected intermittently for fecal corticosterone metabolite analyses. No mouse pairs required separation throughout the dosing phase of study, and no significant differences were observed that would affect toxicology studies. This suggests that by using techniques to decrease agonistic behaviors, male mice can be successfully socially housed on acute and subacute toxicology studies.

Meloxicam is a nonsteroidal anti-inflammatory drug (NSAID) frequently administered every 24 hours to control mild to moderate pain in rodents. Extended-release meloxicam offers a refinement of less frequent dosing and an extended therapeutic window compared with the standard daily-dosed meloxicam formulation. The aim of this study was to compare the analgesic efficacy of 2 different extended-release meloxicam formulations to a standard meloxicam formulation in a rat incisional pain model. Adult Long-Evans rats (n = 33) were randomly assigned into one of 4 treatment groups (n = 8-9 per group): (1) saline (0.9% NaCl, 5 mL/kg, SC, once); (2) meloxicam (Melox; 2 mg/kg, SC, every 24 hours); (3) meloxicam extended-release polymer (Melox-ER; 4 mg/kg, SC, once); or (4) meloxicam extended-release suspension (Melox-XR; 4 mg/kg, SC, once). Under isoflurane anesthesia, a 1-cm longitudinal skin incision was made on the plantar hind paw 5 minutes after drug administration. Mechanical and thermal hypersensitivity assessments were performed one day before surgery (-24 hour), 4 hours after surgery (4 hour), and 3 consecutive days following surgery (24, 48, and 72 hours). Mechanical (4-48 hours) and thermal (4-72 hours) hypersensitivity were observed in the saline group. Melox-ER did not attenuate mechanical or thermal hypersensitivity at any time point. Melox and Melox-XR attenuated mechanical hypersensitivity at the 48-hour time point. No abnormal clinical signs were noted, but injection site reactions were noted in the Melox, Melox-ER, and Melox-XR groups. Further research is needed to evaluate rat meloxicam analgesic dosages for incisional pain.

Warmed inspired air circuits have proved to be effective in semiclosed heating modalities in veterinary species such as dogs, cats, and nonhuman primates, and thus, there is a gap in species requiring a nonrebreathing circuit. This study evaluated the efficacy of using warmed inspired air in addition to conductive mattress warming in the prevention of hypothermia in anesthetized rabbits (Oryctolagus cuniculus). Rabbits were divided into 2 groups: conductive warming only (control) or conductive warming and warmed inspired air. Our results showed that the addition of a warmed air anesthesia circuit had a significant positive effect on perianesthetic body temperature, maintaining a higher rectal temperature starting 10 minutes after induction and a higher final rectal temperature after a 45-minute anesthetic procedure. At 20 minutes after induction, the body temperature of the warmed air group was not significantly different from baseline compared with a significant drop from baseline in the control group. Infrared pinnal temperatures did not show a pairwise significance in the effect of heating modality and time; however, a clinically significant difference of 2-3 °F between groups was seen. There were no statistically significant differences between groups for time to full recovery and time to extubation. For procedures using rabbits, the addition of warmed inspired air should be considered a significant refinement that promotes normothermia during anesthesia based on consistent and improved overall body temperatures.

Simian T cell leukemia virus (STLV) is associated with lymphoma in many captive and wild Old World nonhuman primate (NHP) species and is readily transmitted by bodily fluids. The disease is best characterized in baboons with a predisposition for aged female animals. Asymptomatic infections are common; however, clinical signs may include generalized lymphadenopathy, lethargy, and anorexia. Herein, we report a case of disseminated lymphoma in a middle-aged female STLV-positive olive baboon (Papio anubis) that presented with generalized lymphadenopathy and a rapid onset of decreased visual acuity culminating in full vision loss. Postmortem examination revealed a metastatic focus of lymphoma compressing the occipital cortex and is the presumed mechanism of vision loss. To our knowledge, this is the first report of a neurologic complication associated with an STLV infection in a NHP species.

Intracardiac injection is a commonly used method to establish experimental metastases in mice, particularly in models of breast and prostate cancer. This technique enables rapid dissemination of tumor cells to the skeleton and brain but carries significant animal welfare concerns due to high rates of morbidity, including paralysis, weight loss, and multiorgan failure. This narrative review evaluates the welfare implications of the intracardiac model, synthesizing data from preclinical studies. Alternative techniques, such as intratibial, caudal artery, intracarotid, and intracranial injection, are compared in terms of procedural refinement, disease localization, survival time, and humane endpoints. These methods offer improvements in reproducibility and welfare while maintaining relevance to metastasis research. We discuss how these refinements can reduce animal burden and improve model selection in line with the 3Rs (Replacement, Reduction, and Refinement).

Schistosomiasis, a parasitic disease caused by trematodes of the genus Schistosoma, was eliminated on the island of Saint Kitts in the 1950s after an intense program that targeted the snail intermediate host and improved sanitation. However, recently, 3 cases of schistosomiasis were identified in green monkeys (Chlorocebus sabaeus) imported from Saint Kitts over a period of 5 months from December 2023 to April 2024. The 3 cases each had hepatic manifestations of the disease. In addition, one animal had disseminated disease affecting the cerebrum, cerebellum, brainstem, and lung and is the first described case of neuroschistosomiasis in a non-human primate (NHP) due to infection with Schistosoma mansoni.

The Guide for the Care and Use of Laboratory Animals specifies that sipper tubes require weekly sanitization, although reduced frequency for sterile, disposable caging components may be justified with performance-based assessments; therefore, extending bottle duration beyond 1 week, and replacing instead at a lower volume limit, may be acceptable if it does not compromise mouse health or water quality. Weekly bottle change for sterile, disposable bottles results in excessive waste of both water and plastic-bottles are typically more than half full at 7 days. A volume-based replacement schedule is a visual alternative to weekly changes for systems using sterile, disposable bottles, reducing the number of bottles processed and facilitating operations by allowing spot changes without the need to date or track bottles. Furthermore, the gravity-drip design of Innovive's Aquavive bottle minimizes contamination, suggesting that water quality and cleanliness may be maintained for longer durations. To assess the impact of a volume-based replacement schedule on mouse health and water quality, C57BL/6NCrl mice at varying housing densities were monitored for changes in animal weight and mean water consumption. At bottle replacement, packed cell volume was collected from individual mice as a marker of hydration status, and water quality was assessed by visual inspection, culture for Escherichia coli and coliform bacteria, and total microbial count. Baseline measurements were collected over 7 days, followed by a volume-based replacement period, where bottles remained on the cage until they reached 100 mL (13-47 days). No significant differences were observed in animal body weight, body condition, water consumption, or packed cell volume, regardless of cage density or the amount of time the bottle was deployed. Microbial analysis showed no bacterial growth in any bottle, and visual inspection showed no turbidity or cloudiness. Based on this information, our institution allowed prefilled disposable, acidified water bottles to be maintained well beyond 7 days, using a volume-based replacement at 100 mL.

The Jamaican fruit bat (Artibeus jamaicensis; JFB) is a natural host and current experimental model for many viruses, including Middle East respiratory syndrome virus, dengue virus, Zika virus, rabies virus, influenza virus, tacaribe virus, and most recently SARS-CoV-2, due to their unique immune systems, which allow the harboring and transmission of disease without developing significant clinical disease themselves. In these studies, disease impact can be measured using changes in serum biochemical and protein electrophoretic blood values. However, no currently established reference intervals for JFB exist. In this study, we aimed to define these baseline parameters from our closed bat colony and determine sex differences, if any. We hypothesized that many chemistry values would be similar to other species of frugivorous bats with elevated creatine kinase and glucose due to hand capture and that sex differences would be minimal. One hundred thirty-four adult bats (62 males and 72 females) were randomly selected from an apparently healthy captive population of JFB for isoflurane euthanasia and blood collection by cardiocentesis. Serum samples were routinely processed using commercially available methods. Reference intervals for the total population and both sexes were established using the Reference Value Advisor 2.1 macro for Excel and the nonparametric method in accordance with current guidelines. When compared against reference values for other frugivorous bat species, JFB most notably had increased ALT, AST, GGT, and potassium values. Higher phosphorus and ALP levels may be attributed to sampling of juveniles, while elevated creatine kinase and glucose are secondary to capture. Males had considerably higher cholesterol, while females had higher glucose and γ-globulin. This information on serum biochemical values adds to our knowledge of the normal physiologic parameters of this species and will serve as a useful guide for future studies performed on Jamaican fruit bats.

Diabetes is a global health concern, with increasing prevalence attributed to factors such as obesity and sedentary lifestyles. Nonhuman primates (NHPs), particularly rhesus macaques (Macaca mulatta), serve as valuable models for studying type 2 diabetes mellitus due to their physiologic similarities to humans. However, there are currently no established normal ranges for glycated hemoglobin (A1C) in this species. This study aimed to determine normal A1C values in healthy, nonobese adult rhesus macaques to establish a reference for future diabetes research. A total of 210 Indian origin rhesus macaques (128 males, 82 females) 5-10 years of age were sampled. A1C was measured using the A1CNow+ kit, and blood glucose levels were assessed via a point-of-care glucometer and clinical laboratory analysis. Statistical analyses were performed using R, including a Shapiro-Wilks test for normality, regression analyses, and correlation coefficients. The mean A1C value was 5.92% (range, 4.4%-9.9%), with males exhibiting a mean of 6.07% and females 5.69%. No significant correlations were found between A1C and blood glucose levels, weight, body condition score, or age. However, males had significantly higher A1C levels than females (P = 0.004). Excluding outliers revealed a significant interaction between sex and weight (P = 0.03). The established mean A1C value for healthy adult rhesus macaques is higher than previously reported values for NHPs and human standards. This study provides a critical reference for A1C levels in rhesus macaques, facilitating future diabetes research and improving understanding of type 2 diabetes mellitus in both humans and NHPs.