The domestic supply of nonhuman primates (NHPs) in the United States is not adequate to meet needs for biomedical research, and many NHP research programs rely on imported animals. Since 2020, several disruptions in supply have led importers to purchase NHPs from different foreign sources. This analysis reviews Centers for Disease Control surveillance data to characterize trends in age, weight, and health status in imported NHPs over a 10-year period with the goal of better understanding how changes in supply might affect the health status of imported NHPs. We used linear and binomial regression to explore relationships between shipment characteristics and health status. The source countries of imported NHPs shifted dramatically during the study period, with the majority of animals initially coming from China, then Cambodia, and then Mauritius. Median age and weight declined steadily for most of the study period but have begun to rebound in recent years. Predictors of illness and death in quarantine included lower median shipment weight, larger shipment size, and either China or Vietnam as the source country. The results of this analysis suggest that recent changes in supply may have contributed to an increase in adverse health events in quarantined NHPs. Having a more substantial domestic supply of NHPs for research may help to address these concerns. Until more stable sources of NHPs can be identified, import quarantine remains essential to protect the health of NHP workers.
Animal use in biomedical research continues to present ethical issues regarding justification, care, and welfare. There are differing viewpoints for the continued use of animals in research, testing, and training, and the public can easily search for viewpoints that support a single perspective but rarely are provided with a balanced discussion. An issue of the American Medical Association Journal of Ethics (September 2024, vol. 26, no. 9) exemplifies this problem by providing many views opposing the continued use of animals in research without allowing or providing input from those in the laboratory animal science profession. As a result, many of the views represented in the journal misrepresent important considerations that currently exist when considering the ethical use of animals in research. If a more diverse set of experts, including those with knowledge of laboratory animal medicine, governance, application of the 3Rs, and nonanimal alternatives, were invited into the discussion, we believe that a more accurate perspective of this issue could have been presented. Such diverse viewpoints would have fostered a better atmosphere that more accurately reflects the current reality of how animal use in research is considered by IACUCs. A better understanding of differing perspectives, and with further opportunity for respectful dialogue, could more effectively move this issue forward.
Frequent sanitation of rodent cage accessories is labor-intensive and costly. The Guide for the Care and Use of Laboratory Animals recommends changing tops every 2 weeks but allows performance-based intervals when supported by data. This study evaluated whether mouse wire-bar lid sanitation intervals can be extended to 8 weeks without increasing organic or microbial load. In a 10-week study across 5 cage configurations, wire-bar lids were sampled at weeks 0, 2, 4, 6, 8, and 10. Organic residue was quantified by ATP luminometry (relative light units [RLUs]) and viable bioburden by total plate count (TPC; CFU/cm2) using Hygicult TPC contact agar. Prespecified action thresholds were ATP ≤100,000 RLU and TPC ≤45 CFU/cm2. All values remained below thresholds; ATP was consistently <5% of the action level and TPC maxima <40% of the action level. Two one-sided tests on log-transformed data demonstrated biologic equivalence between week 8 and week 2 across all configurations, with 90% CIs fully within prespecified margins (±10,000 RLU; ±4.5 CFU/cm2). Under these conditions, extending the wire-bar lid sanitation interval to 8 weeks was feasible without evidence of increased organic load or bioburden. Based on facility census and time-and-motion data, the change is projected to save ∼22,075 kWh/y of energy, 166,270 L/y of water, and ∼1,125 labor hours (≈0.54 full-time equivalent). These findings provide site-specific validation supporting performance-based sanitation intervals for wire-bar lids. Implementation should remain performance-validated and site-specific. Future studies may assess other cage components and microenvironmental parameters to support performance-based intervals across the home-cage system.
Living entities, inlcuding laboratory animals, are composed of the host and its associated microbial communities and defined as holobionts. The host genotype and its microbiome drive together as a metagenome, the holobiont phenotype, with the microbiome itself as a well-recognized source of phenotypic variation. Multiple environmental (diet, light/dark cycles, etc.) as well as host-related factors (genotype, maternal effect, etc.) not only influence the animal experimental phenotype but also contribute to the shaping of the microbiome, raising the question of whether the microbiome of experimental animals represents an extrinsic, intrinsic, or intermediate influence. Currently, there is sufficient evidence that microbial communities at different body sites are shaped by distinct endogenous and exogenous factors, indicating that the host does not leave its microbial status to chance but instead actively modulates it through host-specific mechanisms, despite extrinsic influences. This leads to a microbiome that reflects a 'fingerprint' of its own endogenous and exogenous influences. This suggests that the microbiome of experimental animals is an intermediate factor with both intrinsic and extrinsic components and underscores the importance of refining the selection of the appropriate metagenome for each specific rodent experiment.
A 2-year-old female Sprague-Dawley rat (Rattus norvegicus) presented with mild vaginal bleeding and no additional clinical signs. Physical examination revealed a firm intra-abdominal mass and unilateral renal enlargement. Diagnostic evaluation including CBC, serum chemistry, and CT identified neutrophilia, metabolic abnormalities, and a large abdominal mass causing displacement of abdominal organs. Differential diagnoses included urinary tract infection, reproductive tract disease, and neoplasia. Due to poor prognosis, humane euthanasia was performed. Necropsy and histopathology revealed uterine adenocarcinoma with pulmonary metastasis. Splenomegaly was also identified, consistent with disseminated large granular lymphocyte leukemia involvement. This case demonstrates that subtle clinical abnormalities in aged laboratory rats may represent severe disseminated neoplastic disease.
