Analgesic regimens for laboratory-housed avian species remain poorly defined, with limited pharmacokinetic data available, particularly in passerine birds. This study characterized the pharmacokinetics of extended-release (ER) meloxicam in tufted titmice (Baeolophus bicolor) following single subcutaneous dosages of 3 and 6 mg/kg. We hypothesized ER meloxicam would sustain therapeutic plasma concentrations (>3,500 ng/mL), previously established in zebra finches and larger avian species, for 72 hours. Pharmacokinetic analysis revealed significantly higher Cmax and faster clearance at 6 mg/kg compared with 3 mg/kg. Although therapeutic plasma levels (>3,500 ng/mL) were observed at 1 hour postadministration, concentrations decreased below previously established therapeutic thresholds by 4 hours postinjection at both dosages. Histopathologic examination revealed no significant drug-related adverse effects. These findings suggest subcutaneous administration of ER meloxicam at 3 and 6 mg/kg does not sufficiently prolong therapeutic analgesia in tufted titmice, with a shorter therapeutic duration of action than previous findings with intramuscular meloxicam in small passerines.
Japanese macaques ( Macaca fuscata ) are used in biomedical research where frequent, small-volume blood sampling for monitoring the animal’s health may be required. Femoral blood collected under anesthesia is the standard for obtaining CBC analyses from nonhuman primates to assess their health. However, anesthetizing animals to obtain these collections may not be ideal due to adverse impacts of frequent anesthesia. Cage-side blood sampling from the pinna of the ear is a convenient and less invasive method for blood collection without anesthesia. However, it is unknown whether hematologic parameters from blood collected from the pinna are representative of femoral blood collections. The objective of this study was to determine whether hematologic parameters obtained from blood collected from the pinna of the ear can be used as a surrogate for hematologic parameters from blood collected from the femoral vein in Japanese macaques. Ten male Japanese macaques were trained to present their pinnae for blood collections without anesthesia, after which the macaques were anesthetized for pinna and femoral blood sampling for comparison. Anesthesia, rather than blood sampling site, was responsible for statistically significant differences in leukocyte parameters between pinna and femoral blood samples. In contrast, differences in erythrocyte and platelet parameters between pinna and femoral blood were driven by the collection site, with anesthesia contributing to a lesser degree. While statistical differences were identified, the clinical relevance of these differences was minimal. Taken together, this study indicates that cage-side pinna blood samples collected from conscious Japanese macaques are different than femoral blood samples collected under anesthesia but are suitable for frequent hematologic monitoring.
Considering animal welfare in research is an important part of ethical professional practice. However, not all animal species are covered by welfare legislation, resulting in less consideration for currently unprotected groups. While ethical arguments for protecting animal welfare are commonly debated, practical arguments have received less attention. Here, we review literature from vertebrate laboratory animals, demonstrating practical benefits to welfare consideration by highlighting the links between animal welfare and (1) improving scientific outcomes; (2) maintaining public support for research; and (3) reducing occupational stress. We then extend these practical arguments to the invertebrate research context. Using mammals as the focal taxa for vertebrates and insects as the focal taxa for invertebrates, we show how research suggests that researchers working with some invertebrate taxa may similarly benefit from the consideration of animal welfare. Together, this literature provides evidence that considering animal welfare may facilitate scientific progress across taxa. We close with practical guidance for researchers working with plausibly sentient taxa on how to incorporate animal welfare considerations into their scientific practice.
Accurate urine collection is essential for preclinical studies involving metabolism, toxicology, and disease modeling. However, conventional methods such as metabolic caging and manual restraint are often invasive, labor intensive, prone to contamination, and not scalable for large cohorts, while also raising animal welfare concerns. This study presents a noninvasive and practical technique for collecting spot urine samples from healthy and tumor-bearing mice developed as a refinement to existing collection approaches. The method involves positioning the mouse in a natural voiding posture by allowing the hindlimbs to hang freely while the forelimbs grip a wire bar feeder, thereby stabilizing the animal and reducing excessive movement. Gentle abdominal pressure is applied only when needed. The method was validated in 80 C3H/HeJ and athymic nude mice, including both healthy and tumor-bearing (fibrosarcoma or prostate cancer [PC3]) models. Using this approach, spot urine volumes ranging from 13 to 200 µL were reliably collected from all mice, with each successful collection completed within 1 minute. Urine was successfully collected on the first attempt in ∼70% of cases. The mean urine yield was 51.7 ± 38.9 µL for healthy females, 53.7 ± 28.5 µL for healthy males, 50.8 ± 20.2 µL for tumor-bearing females, and 52.2 ± 28.1 µL for tumor-bearing males, with no statistically significant difference (P > 0.05) in urine volume distributions between groups. No visible fecal or particulate contamination was observed during sample collection. The collected volumes are sufficient for a wide range of molecular and metabolic analyses, ensuring the method's applicability in diverse research settings. Unlike other techniques that involve excessive handling, this method requires no restraint devices, making it well suited for large cohort studies and repeated sampling. The proposed technique represents a practical refinement in preclinical research by offering an optimal balance between sample quality, animal welfare, and experimental efficiency.
Environmental health monitoring (EHM) has gained attention as a sensitive, animal-free alternative to soiled bedding sentinel (SBS) programs for microbiologic surveillance in laboratory animal facilities. Although several EHM approaches have been validated in facilities using IVC systems, empirical evidence supporting room and equipment monitoring (REM) remains limited, particularly in open-top housing environments. This study evaluated the feasibility and practical applicability of environment-derived dust-based REM in an open-top housing facility using open-top cages and open racks. Microbial capture at room exhaust outlets was first assessed by culture-based analysis of exhaust prefilters in mouse, rat, and rabbit rooms. In parallel, exhaust louver-derived dust (ELD) was collected from downstream exhaust duct louvers and analyzed by PCR. To enable more frequent and standardized sampling, floor-derived dust (FDD) was collected using robotic cleaning devices and subjected to PCR analysis. The impact of robotic cleaning on environmental hygiene and welfare was evaluated using ATP-based cleanliness testing and noise measurements. Environmental microorganisms were consistently captured on exhaust prefilters, including in rooms without animals. PCR-based testing successfully detected microbial nucleic acids in both ELD and FDD samples across multiple facility zones, demonstrating the feasibility of REM in an open-top housing system. Robotic-based dust collection provided sufficient material for repeated testing under routine facility operation, without compromising environmental cleanliness or exceeding acceptable noise levels. These findings suggest that environment-derived dust-based REM can be implemented as a facility-level surveillance approach in open-top housing facilities, offering an animal-free, time-integrated monitoring strategy aligned with the principles of the 3Rs (Replacement, Reduction, and Refinement).
Dental radiology is a valuable diagnostic tool commonly used during comprehensive oral health assessments and treatments (COHAT) and oromaxillofacial surgical procedures in companion animals and humans. However, standardized techniques for dental radiography in rhesus macaques (Macaca mulatta) remain underdeveloped. This study aimed to establish practical and reproducible methods for obtaining high-quality dental radiographs in rhesus macaques using the handheld X-ray system. Initially, anatomic landmarks, optimal X-ray beam, and sensor angles were determined using a preserved rhesus macaque skull. These techniques were subsequently applied to 12 anesthetized rhesus macaques for dental radiographic assessment and presurgical planning. Radiographs were successfully obtained for maxillary and mandibular incisors, canines, premolars, and molars. In addition, several examples of common dental pathologies, including periodontal disease, root resorption, and tooth fractures, were documented. This study provides detailed techniques for dental radiography in rhesus macaques, demonstrating its utility as a diagnostic adjunct for identifying dental pathology and planning oromaxillofacial surgical procedures. The use of dental radiographs enhances diagnostic accuracy, improves surgical outcomes, and contributes to the overall welfare of rhesus macaques in research and clinical settings. These findings establish a foundation for the broader application of dental radiology in nonhuman primates and underscore its importance in advancing veterinary care.
Sedation in nonhuman primates (NHPs) is commonly achieved with ketamine (KET), which provides short-term (less than 30 minutes) sedation but is associated with undesirable side effects such as twitching, increased jaw tone, and hypersalivation. This study investigates the use of dexmedetomidine (DEX) in cynomolgus macaques (Macaca fascicularis) as a potential alternative or adjunct sedative. Four experiments were conducted to determine: (1) the safety and efficacy of DEX as a sole sedative; (2) optimal dose combinations of DEX and KET; (3) a comparison of DEX/KET sedation outcomes to historical KET-only sedation data; and (4) a comparison of the sedation duration of DEX/KET combinations to KET alone. First, we evaluated escalating doses of DEX (0.02-4.04 mg/kg), and in 11 of 14 attempts, animals remained rousable and maintained posture for up to 90 minutes. Then, we used a fixed DEX dose (0.75 mg/kg) combined with escalating KET doses (1.0-2.252 mg/kg) to reduce overall KET exposure and successfully achieved 90 minutes of sedation. We then compared DEX/KET sedation outcomes to prior KET-only sedation records, revealing fewer instances of emesis, less food waste, and improved repairing success with DEX/KET. Finally, KET alone (10 mg/kg) or a DEX/KET combination (0.75 mg/kg DEX and 2.25 mg/kg KET) was evaluated for routine colony management procedures without atipamezole (ATI) reversal. The DEX/KET group exhibited significantly longer sedation durations with reduced hypersalivation and vomiting compared with the KET-only group. These experiments demonstrated that DEX alone was insufficient for sedation in macaques at the tested doses and had no adverse outcomes at significantly higher doses than previously reported. We recommend a DEX/KET dose of 0.75 mg/kg DEX and 2.25 mg/kg KET to provide sedation and reduce side effects (vomiting, food waste).
The use of laboratory opossums (Monodelphis domestica) in biomedical research has increased since the 1980s, when the first colonies were established in the United States, due to their relatively low maintenance requirements and cyclical breeding patterns resulting in reproductive efficiency. Despite their growing use, reproductive disorders in this species remain poorly characterized. A 2.5-year-old female laboratory opossum was euthanized for humane reasons after presenting lethargy, inappetence, and a severely distended abdomen. Gross necropsy revealed marked uterine enlargement. Cytologic evaluation demonstrated the presence of septic endometrial fluid, and aerobic bacterial culture yielded heavy growth of Escherichia coli and Stenotrophomonas maltophilia. Histopathologic examination confirmed suppurative endometritis (pyometra) with concurrent pyosalpinx and endometrial adenocarcinoma. Subsequently, 3 additional cases of pyometra were identified within the same colony, prompting further evaluation. These 4 affected animals (ages 2.1-2.52 years) were all from the PBP strain and demonstrated consistent clinical and reproductive features. Common findings included infertility or reduced reproductive success, abdominal distension, lethargy, and lumbosacral alopecia. To assess the novelty of this finding, a comprehensive literature search was conducted using Google Scholar, PubMed, ScienceDirect, and Web of Science, with keywords related to laboratory opossums, marsupials, and reproductive pathology. No prior reports describing histopathologic features of pyometra or associated neoplasia in M. domestica were identified. This case series suggests that pyometra may represent an underrecognized reproductive condition in laboratory opossums, potentially associated with age, reproductive history, and strain-specific factors. Recognition of these clinical patterns is important for colony health monitoring, reproductive management, and minimizing potential confounding effects on research outcomes.
Orthotopic tumor models are critical to the development of new cancer therapies, as they have the greatest potential to mimic human cancer progression. However, such models are often underutilized due to practical challenges. These challenges include the need for specialized surgeries and the presence of complicating symptoms, such as ascites fluid accumulation in ovarian cancer and liver disease models, as well as ulceration of breast tumors growing in the mammary fat pad. An adaptable, quantitative animal health assessment system that employs simple, noninvasive visual measurements can enable researchers to realize the full potential of these models while safeguarding humane endpoints. The goal of this work was to establish health-scoring systems for translationally relevant ovarian (ID8-Defb29/Vegf-A) and breast cancer (triple-negative 4T1) models. We developed a tractable health assessment system by monitoring a combination of activity and responsiveness, hair coat condition, respiratory function, changes in body weight, posture, gait, tumor size (where measurable), and extent of ulceration, and scoring each parameter on a simple numerical scale. The scores at which euthanasia or other interventions were required were estimated and then adjusted based on clinical assessment by a team of researchers and veterinarians. These semiquantitative health-scoring systems were applied to survival experiments, in which mice were euthanized at a predetermined score or upon meeting a superseding health criterion, to confirm their applicability and effectiveness in maintaining humane endpoints. The scoring systems presented are intended to build on previously established generic tumor model scoring systems that do not account for the particular phenotypes present in orthotopic breast and ovarian cancer models.
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.
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.
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.
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.
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/cm 2 ) using Hygicult TPC contact agar. Prespecified action thresholds were ATP ≤100,000 RLU and TPC ≤45 CFU/cm 2 . 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/cm 2 ). 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.
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.
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.
