J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42349879
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Colitis cystica profunda (CCP) is a rare benign lesion in humans that can mimic, clinically and radiologically, a malignant neoplasm. CCP etiopathogenesis is poorly understood and believed to be due to congenital ectopia...Colitis cystica profunda (CCP) is a rare benign lesion in humans that can mimic, clinically and radiologically, a malignant neoplasm. CCP etiopathogenesis is poorly understood and believed to be due to congenital ectopia or associated with chronic inflammation. Despite sporadic reports of CCP in animals, there are no established animal models for the study of this disease. Here, we briefly review CCP in humans and animals with a discussion of the possible etiopathogenesis and potential animal models.
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42349877
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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 th...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.
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42336358
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Sanitation frequencies for rat caging in the research setting are largely based on recommendations from the Guide for the Care and Use of Laboratory Animals and extrapolated from mouse studies evaluating extended cage-ch...Sanitation frequencies for rat caging in the research setting are largely based on recommendations from the Guide for the Care and Use of Laboratory Animals and extrapolated from mouse studies evaluating extended cage-change intervals and different bedding types. This study sought to develop evidence-based recommendations for rat husbandry practices by comparing the impact of paper pulp cellulose (PPC) and corncob (CC) bedding on IVC microenvironments over a 7-, 14-, and 21-day cage-change frequency. Ammonia levels, urine latrine sizes, and overall health of the animals were evaluated over this time. At days 7, 14, and 21 results demonstrate mean ammonia levels of 59.2, 118.4, and 114 ppm for PPC and 7.3, 79.9, and 104.3 ppm for CC as well as average latrine sizes of 2.8, 21.4, and 37.2 cm2 for PPC and 40.5, 185, and 283 cm2 for CC, respectively. A cost-savings analysis compared annual personnel labor costs associated with various cage-change frequencies as well as cost differences in bedding type. This analysis demonstrated that 14- and 21-day intervals and the switch from CC to PPC bedding both provide cost savings benefits.
Koo BS, Nederlof RA, Jeon E
… +4 more, Bae GS, Kim DS, Hong JJ, Bakker J
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42320893
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The amount of biologic data produced by biomedical research has increased significantly in both volume and complexity in recent years. Advances in computational power have increasingly enabled the use of machine learning...The amount of biologic data produced by biomedical research has increased significantly in both volume and complexity in recent years. Advances in computational power have increasingly enabled the use of machine learning (ML) to analyze and predict patterns from large-scale, complex biologic datasets. In nonhuman primate (NHP) infectious disease models, such high-dimensional datasets containing a large number of features are often obtained by next-generation sequencing-based multiomics and immunologic analyses. As a result, ML is particularly valuable for effective analysis and predictive modeling in this context. This review demonstrates that the application of ML in NHP infectious disease models has increased over time. Ensemble methods, particularly random forest, have emerged as the most frequently used algorithms, followed by regression and clustering approaches. Logistic regression and hierarchical clustering were the most commonly applied regression and clustering methods, respectively. These techniques are primarily used for vaccine response prediction, biomarker discovery, disease progression analysis, gene and pathway identification, and immune response characterization. Despite this increasing trend, the overall adoption of ML in NHP infectious disease models remains limited, which may reflect gaps in familiarity and computational expertise among researchers. Recent advances in generative artificial intelligence and user-friendly analytical platforms are expected to improve accessibility and promote broader adoption. This review aims to support understanding and facilitate wider application of ML in NHP infectious disease models.
Petersson AJ, Särén LE, Kroon LM
… +2 more, Hallengren LC, Östman SM
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42320891
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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 suppor...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.
Benga L, Rehm A, Gougoula C
… +2 more, Bischoff S, Janssen S
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42315187
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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 holobio...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.
Justo AA, Sanches MC, Sladky KK
… +2 more, Lima CFM, Carregaro AB
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42307566
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This prospective, randomized, complete crossover study evaluated the psychometric properties of a behavioral sedation scale in 8 adult green iguanas (Iguana iguana) following intramuscular administration of midazolam (2...This prospective, randomized, complete crossover study evaluated the psychometric properties of a behavioral sedation scale in 8 adult green iguanas (Iguana iguana) following intramuscular administration of midazolam (2 mg/kg) or saline. Each animal underwent both treatments with a washout period of 7 days. Sedation was assessed in real time using a previously described behavioral scale comprising eye opening, head height, muscle tone, handling, and body righting reflex, with total scores ranging from 1 to 14. Assessments were performed at baseline and at multiple time points up to 360 minutes postinjection. Construct validity was assessed by comparing sedation scores over times, and internal consistency was calculated using the Cronbach α coefficient. A total of 23 videos were used to evaluate intra- and interrater reliability by 2 blinded, untrained observers experienced in lizard anesthesia. Midazolam significantly increased sedation scores compared with baseline from 10 to 120 minutes postinjection (P = 0.015 to P < 0.001), and scores were higher in midazolam-treated iguanas than in controls up to 300 minutes (P = 0.007). Internal consistency was excellent (Cronbach α = 0.835). Intrarater reliability was very good for total scores (intraclass correlation coefficient > 0.98) and individual items (weighted κ > 0.80). Interrater reliability ranged from poor to very good, with wide confidence intervals (95% intraclass correlation coefficient, 0.18-0.95), and disagreement between observers exceeded 1 point in 47.8% of videos. Strong correlations were observed between real-time and video-based scores (Spearman rs ≥ 0.9). These findings indicate that the scale effectively discriminates sedation and demonstrates strong internal consistency and repeatability; however, variability between observers suggests that training may be required to optimize its clinical application.
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42307561
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Within a 2-year period, 5 adult, single-housed, northern tree shrews (Tupaia belangeri) presented for a range of clinical signs including lethargy, hindlimb lameness, decreased visual acuity, polyuria, and polydipsia. Di...Within a 2-year period, 5 adult, single-housed, northern tree shrews (Tupaia belangeri) presented for a range of clinical signs including lethargy, hindlimb lameness, decreased visual acuity, polyuria, and polydipsia. Diagnostic findings, including point-of-care blood glucose and ketone measurements, urine dipstick analysis, insulin, fructosamine, and glycosylated hemoglobin levels, and gross and histopathologic lesions, were consistent with a diagnosis of type 2 diabetes mellitus. Although spontaneous diabetes mellitus has been reported in other members of the order Scandentia, to our knowledge, this represents the first published case series describing naturally occurring type 2 diabetes mellitus in the northern tree shrew.
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42307557
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Anesthesia-induced lens opacity has been reported in rats and mice and is characterized as acute and reversible. In ophthalmologic research, lens opacity often interferes with the accurate acquisition of ocular data. In...Anesthesia-induced lens opacity has been reported in rats and mice and is characterized as acute and reversible. In ophthalmologic research, lens opacity often interferes with the accurate acquisition of ocular data. In this study, we investigated the usefulness of alfaxalone, an anesthetic known for its favorable safety profile, for prevention of anesthesia-induced lens opacity in rats. First, anesthetic protocols using alfaxalone were screened to identify those suitable for the study. Then, the induction profiles of transient lens opacity following intraperitoneal administration of alfaxalone-butorphanol and alfaxalone-midazolam-butorphanol were evaluated, and the findings were compared with those obtained for ketamine-xylazine, which is known to induce lens opacity. Lens opacity induced by alfaxalone-based anesthetic combinations was significantly milder than that induced by ketamine-xylazine. Alfaxalone-based anesthetic combinations suppressed reflex responses, and alfaxalone-midazolam-butorphanol provided sufficient depth and duration of anesthesia for morphology-based assessment of the eye, although the depth of anesthesia was lower than that achieved with ketamine-xylazine. In conclusion, the combination of alfaxalone, midazolam, and butorphanol may represent a promising anesthetic option for ophthalmologic studies in rats.
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42307556
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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...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.
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42307535
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Studies involving rodent models of acute lung injury infrequently use oxygen saturation to characterize lung injury, even though it is the principal standard by which physiologic lung dysfunction is measured in humans. A...Studies involving rodent models of acute lung injury infrequently use oxygen saturation to characterize lung injury, even though it is the principal standard by which physiologic lung dysfunction is measured in humans. Assessing the clinical progression of lung injury in rodent models presents challenges due to their small size and limited ability to correlate physiologic outcomes with human disease. Furthermore, traditional methods for assessing lung injury rely on invasive techniques, including leukocyte quantification in lung tissue, analysis of bronchoalveolar lavage fluid, and histopathologic evaluation, most of which require euthanasia and preclude longitudinal assessments in the same animal. While body weight is a commonly used indicator of morbidity, additional noninvasive metrics such as pulse oximetry, heart rate, and respiratory rate may offer deeper insights into host responses. Here, we used the MouseOx Plus in conscious mice with a lipopolysaccharide (LPS)-induced lung injury to monitor cardiopulmonary parameters and determine whether there is a correlation between peak hypoxemia, body weight, and heart rate with the severity of the lung injury as defined by histologic assessment. We also evaluated the use of anesthesia to immobilize animals for collecting cardiopulmonary data, as is commonly done, and found that arterial saturation measurements were not significantly different in awake compared with anesthetized animals. However, body weight recovery was significantly decreased in anesthetized groups on days 4-5. Together, these data support the use of conscious pulse oximetry as a refinement method that noninvasively increases the rigor of the clinical data collected in mice with LPS-induced lung injury.
White NS, Allen J, Delva-Wiley J
… +3 more, Lamont K, Lee S, Williams MD
J Am Assoc Lab Anim Sci
· 2026 Jun · PMID 42235944
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Body temperature is an important clinical parameter in mice and can help refine humane endpoints in research models. However, due to their small size, accurate measurement of body temperature in neonatal and juvenile mic...Body temperature is an important clinical parameter in mice and can help refine humane endpoints in research models. However, due to their small size, accurate measurement of body temperature in neonatal and juvenile mice presents challenges. While rectal temperature is precise, it is invasive and stressful to both neonates and dams. Infrared technologies offer a potential alternative for assessing the body temperature of young mice. This study compared traditional rectal temperature to 3 alternative noninvasive methods: a surface probe and 2 infrared-based approaches (rodent infrared and human infrared). For each alternative method, temperature was measured at 3 different anatomic locations (dorsum, abdomen, and thorax). Temperatures were measured in mice of various ages from postnatal day (PND) 2-42. Temperature measurements were obtained in awake C57BL/6J (n = 114) and BALB/cJ (n = 113) mice to establish baseline neonatal mouse body temperature as they develop thermoregulation. Two strains of mice were used to determine whether coat color impacts infrared temperature readings. Results indicate that body temperature significantly changes as mice age for both strains. Temperatures from all 3 alternative temperature methods at all anatomic locations were significantly lower relative to rectal temperature. The surface probe had little variability among anatomic locations and closely followed the trend of the rectal thermometer with an average difference of 2.1-2.22 °C lower than rectal temperature. Of the methods assessed, the surface probe was the best alternative method to rectal temperature. These results provide valuable baseline data on normal neonatal mouse body temperature for 2 commonly used strains and suggest the surface probe could provide an alternative for body temperature measurement in young mice.
Wang AI, Duong MP, Frohlich JR
… +3 more, Krueger LD, Yaksh TL, Jenné KJ
J Am Assoc Lab Anim Sci
· 2026 May · PMID 42215025
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Systemic analgesics, such as opioids and nonsteroidal anti-inflammatory drugs, may be contraindicated in certain studies due to their mechanisms of action and risk for systemic effects. Local anesthetics (LAs) are theref...Systemic analgesics, such as opioids and nonsteroidal anti-inflammatory drugs, may be contraindicated in certain studies due to their mechanisms of action and risk for systemic effects. Local anesthetics (LAs) are therefore crucial in managing postoperative pain, potentially decreasing the need for systemic analgesics. However, the utility of standard formulation LAs is limited by their short duration. This study evaluated the use of a commercially available extended-release (XR) liposomal bupivacaine (LB) in a mouse paw incisional model. Our goal was to assess whether LB attenuates postoperative mechanical hypersensitivity (MH) and thermal hypersensitivity (TH). Adult female and male C57BL/6NCrl mice were randomly assigned to one of 3 groups: (1) 5 mg/kg SC meloxicam plus 3.25 mg/kg SC XR-buprenorphine (MELOX/XR-BUP); (2) 2 mg/kg intraincisional standard bupivacaine (SB); or (3) 6 mg/kg intraincisional LB. MH and TH were assessed on days -1 (baseline), 0 (2 hours postoperatively), 1, 2, 3, and 4 using von Frey and Hargreaves testing, respectively. Hind paw incisional surgery was performed on day 0. Both the MELOX/XR-BUP and SB groups demonstrated significant attenuation of MH on all postoperative days compared with baseline, while the LB group showed significant attenuation of MH on days 1-4. In the MELOX/XR-BUP group, there was a significant reduction in TH on days 1-3. In both the SB and LB groups, there was no significant reduction in TH across all postoperative days. Together, these data suggest that a single 6-mg/kg intraincisional dose of LB in C57BL/6NCrl mice does not attenuate TH over a 4-day postoperative period but does attenuate MH on postoperative days 1-4 in our incisional model. In comparing the treatments, we conclude that the relative ability of LB to attenuate postoperative MH and TH was inferior to that of MELOX/XR-BUP and comparable to that of SB in a mouse paw incisional model.
Beckers KF, Johnson K, Greely JW
… +2 more, Falkenstein KP, Russell-Lodrigue KE
J Am Assoc Lab Anim Sci
· 2026 May · PMID 42215023
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Pelvic organ prolapse (POP), including vaginal prolapse, is a prevalent reproductive condition in human and veterinary medicine, yet spontaneous cases are underreported in rhesus macaques (Macaca mulatta). This case stud...Pelvic organ prolapse (POP), including vaginal prolapse, is a prevalent reproductive condition in human and veterinary medicine, yet spontaneous cases are underreported in rhesus macaques (Macaca mulatta). This case study describes the clinical progression and successful surgical intervention of severe, recurrent vaginal prolapse in 2 pregnant, multiparous rhesus macaques at the Tulane National Biomedical Research Center (TNBRC). Over a multiweek period, one of the females experienced multiple prolapse episodes, including postpartum recurrence and failure of conservative management (manual reduction, suture retention techniques, and supportive care). The other female experienced multiple episodes during late gestation that continued despite conservative management. Definitive treatment was achieved through a novel abdominal approach involving uterine and cervical fixation to the rectus abdominis fascia, which resulted in anatomic correction and postoperative stability. A retrospective review of TNBRC records from 2005 to 2024 revealed 21 cases of vaginal prolapse with varied outcomes ranging from spontaneous resolution to euthanasia. Over this 20-year period, the prevalence was 4.71 per 1,000 females, with the most severe cases occurring in obese, multiparous individuals. This report demonstrates a practical and effective surgical alternative for managing severe or recurrent prolapse in rhesus macaques, particularly in reproductive-aged females where preservation of fertility and welfare is prioritized. The findings support the need for a species-specific prolapse grading system and highlight key risk factors such as parity, gestational age, infant size, and pelvic tissue integrity. These cases underline the importance of early detection, comprehensive supportive care, and individualized surgical planning in nonhuman primates, while providing a translational model for POP in women.
Han D, Lee J, Kwon H
… +6 more, Shin D, Choi B, Park Y, Kim C, Jeong BC, Park JB
J Am Assoc Lab Anim Sci
· 2026 May · PMID 42184984
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Animal experimentation is conducted under regulatory and institutional frameworks that require ethical standards, safety management, scientific validity, and compliance with relevant guidelines. Accordingly, institutions...Animal experimentation is conducted under regulatory and institutional frameworks that require ethical standards, safety management, scientific validity, and compliance with relevant guidelines. Accordingly, institutions that conduct preclinical research are responsible for providing structured training programs that prepare researchers to conduct animal experiments appropriately. However, empirical evaluations of such training programs and their outcomes remain limited. This study evaluated a comprehensive preclinical animal experimentation training program covering ethics, regulatory requirements, safety, and technical knowledge, using survey data collected from researchers who completed the program at Samsung Medical Center. The Kirkpatrick training evaluation model was applied as an analytical framework, and partial least squares structural equation modeling (PLS-SEM) was used to explore researchers' perceptions of animal experimentation conduct. The results demonstrated that the training program was associated with improved researcher perceptions, supported by acceptable reliability and validity of the measurement instrument. In particular, perceptions related to animal research ethics were significantly associated with experimental performance. An exploratory structural model was developed to identify key determinants of researcher perceptions and to support future refinement of training evaluation approaches. These findings suggest that well-designed training programs can foster ethically grounded and practically oriented attitudes among researchers, thereby strengthening accountability in animal experimentation and supporting the implementation of the Replacement, Reduction, and Refinement (3Rs) principles. This study provides evidence-based insights for institutions, training coordinators, and oversight bodies seeking to improve laboratory animal research training programs.
J Am Assoc Lab Anim Sci
· 2026 May · PMID 42184982
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Prairie voles (Microtus ochrogaster) are highly social rodents that have become a valuable animal model for studying social attachment, pair bonding, parental care, and the neurobiological mechanisms underlying social be...Prairie voles (Microtus ochrogaster) are highly social rodents that have become a valuable animal model for studying social attachment, pair bonding, parental care, and the neurobiological mechanisms underlying social behavior. In recent years, due in part to the publication of the prairie vole genome and deeper mechanistic understanding of their social behavior, prairie voles have become a more popular research model, especially for translational research. However, generating reliable and reproducible findings requires effective colony management, including thoughtful breeding strategies, consistent husbandry practices, and clear documentation. In this paper, we describe the demographic history of, and husbandry techniques employed for, our prairie vole breeding colony at the University of California, Davis from 2004 to 2020. Well-organized and transparent colony management allows for the preservation of informative behavioral traits in prairie voles and strengthens the impact of the prairie vole model across behavioral and biomedical science.