Lab Animal

Delivery of gene therapy vectors targeted to any somatic cell remains a key barrier for the development of genetic medicines. While rodent models provide insights into vector biodistribution and cellular tropism, their anatomical and physiological differences from humans limit their translational potential and studies in large animal models are often required. In this study, we developed a swine reporter model (SRM-1) to evaluate both viral and nonviral vector delivery in a large animal system. The SRM-1 model harbors a Cre- and CRISPR-activated tdTomato reporter at the Rosa26 locus that allows for tracing of cell-specific delivery and expression of gene therapy vectors in vivo. To evaluate this model, we administered adeno-associated virus serotype 9 (AAV9) and lipid nanoparticles (LNPs) carrying mRNA systemically and found successful in vivo reporter activation across a variety of tissues. Intracerebroventricular (ICV) administration of LNP-Cre mRNA was also performed and demonstrated localized activation in cortical brain cells. In addition to biodistribution studies, this model has utility for testing safety and clinically relevant administration methods, surgical and non-surgical, of delivery vectors. Our findings support the SRM-1 model as a valuable tool for advancing gene therapies from preclinical testing to clinical application.

Extracellular vesicles (EVs) are critical mediators of cellular communication, with significant potential for disease diagnosis, therapeutics, and other industrial applications. However, translating EV-based innovations into real-world products faces substantial challenges, particularly concerning regulatory frameworks and scientific gaps. To address these issues, the International Society for Extracellular Vesicles (ISEV) established the Translation, Regulation, and Advocacy Committee (ISEV-TRA) to create an environment that facilitates the translation of EV research into practical societal applications. This reporet presents the results of the first survey conducted by the ISEV-TRA, assessing the degree to which EVs have been translated into society applications, awareness of EV potential, and the current use of EVs across various industry sectors. Respondents included individuals from Academia, Industry, and dual affiliation (Academia-Industry), provided an initial perspective on EV research and its translational status. The survey highlights the growing interest in EV-based products, suggesting that there is an important wave of efforts to develop these products. Several spin-outs created by academic researchers are focusing on EV-based products, a key trend in the field, while large companies are showing increasing interest in EV-based technologies. The expectations and suggestions for the newly established ISEV-TRA underscore the need for a unified approach to accelerate the translation of EV-based technologies into practical applications. The ISEV-TRA is well-positioned to play a key role by providing essential resources, organizing workshops, and promoting interdisciplinary collaboration, ultimately driving the commercialization of EV-based innovations.

BackgroundThe 21st Century Cures Act (2017) expanded FDA flexibility in applying methodological standards for drug approval. To examine trends before and after implementation, we independently reviewed all novel drugs approved between 2016 and 2024. MethodsWe constructed a database of all novel FDA approvals from January 1, 2016, through December 31, 2024. Each study linked to an approved drug (N=6,763) was cataloged by study number, sponsorship, and timing of results reporting relative to completion. ResultsSince 2016, the number of studies supporting approval has steadily declined. Beginning in 2017, the modal number of studies per approval fell to one. Industry sponsorship increased while NIH-supported studies decreased. Average time to public posting of results exceeded the one-year statutory limit. ConclusionsAfter implementation of the Cures Act, FDA approvals have relied on fewer, increasingly industry-sponsored studies. Although this may accelerate access to new therapies, it raises concerns about the strength of evidence for safety and effectiveness.

Adequate pain management is essential for ethical and scientific reasons in animal experiments and should completely cover the period of expected pain without the need for frequent re-application. However, current depot formulations of Buprenorphine are only available in the USA and have limited duration of action. Recently, a new microparticulate Buprenorphine formulation (BUP-Depot) for sustained release has been developed as an alternative product within Europe. Pharmacokinetics indicate a potential effectiveness for about 72h. Here, we investigated whether the administration of the BUP-Depot ensures continuous and sufficient analgesia in two mouse femoral fracture models and could therefore serve as a potent alternative to the application of Tramadol via drinking water. Both protocols were examined for analgesic effectiveness, side effects on experimental readout, and effects on fracture healing outcomes in male and female C57BL/6N mice. The BUP-Depot provided effective analgesia for 72h, comparable to the effectiveness of Tramadol in drinking water. Fracture healing outcome was not different between analgesic regimes. The availability of a Buprenorphine depot formulation for laboratory animals in Europe would be a beneficial addition for extended pain relief in mice, thereby increasing animal welfare.

BackgroundCervical Lymphatic-Venous Anastomosis(LVA) holds therapeutic potential for Alzheimer disease (AD). However, a validated AD animal model for preclinical investigation remains lacking. This study aimed to establish and standardize LNVA, as a form of lymphatic-venous Anastomosis, in a murine AD model; to quantitatively assess its surgical learning curve; and to create a platform for mechanistic exploration and translational research. MethodsWe established and standardized a deep cervical lymph node-to-vein anastomosis (DC-LNVA), a specific type of lymphatic-venous anastomosis (LVA), in rodents. A two-stage training program was applied to a junior surgeon: 60 DC-LNVA procedures were performed in 30 small Sprague-Dawley rats (50-60g), followed by 20 bilateral anastomoses in 10 male 5XFAD mice. Surgical proficiency was evaluated using procedure time, UWOMSA scoring, and CUSUM analysis. Anatomical parameters were assessed with ImageJ. Anastomotic patency was confirmed via ICG lymphangiography. Intranasal Evans Blue was used to trace cranial distribution pathways. ResultsSD rats had significantly larger external jugular veins (0.376 {+/-} 0.013 mm vs. 0.228 {+/-} 0.011 mm) and DCLNs (1.359 {+/-} 0.084 mm2 vs. 0.333 {+/-} 0.022 mm2) than mice (P < 0.0001). Proficiency was achieved after 27 anastomoses in rats and 10 in mice. ICG confirmed 100% patency in 9 surviving 5XFAD mice. Evans Blue suggested a nasal-cranial pathway for tracer distribution. ConclusionWe developed and validated a cervical lymphatic-venous bypass (LVA) in transgenic AD mice. This platform complements existing loss-of-function approaches and offers a foundation for mechanistic and translational research into brain lymphatic clearance.

BackgroundOral gavage is the standard method for delivering drugs and other substances orally in rodent studies, but it can cause significant stress and risk injury. To improve animal welfare and reduce confounding stress effects, this study aimed to replace oral gavage by developing and testing a new voluntary ingestion method that is easy to adopt, minimizes stress in mice, and is suitable for a wide range of compounds. ResultsWe developed a soft agar formulation with an appealing scent and taste that mice readily consumed without fasting or restraint. We called this method "unconstrained dosing agar" (UDA). Analysis of fecal corticosterone levels demonstrated that the method is associated with low stress in the animals. After training, mice quickly consumed the agar units. Body weight gain was unaffected by the treatment. ConclusionsThis study introduces a simple, low-stress method for administering substances orally in mice. By encouraging voluntary consumption and removing the need for fasting or restraint, this method provides a practical alternative to oral gavage and could improve animal welfare and experimental consistency.

Nanoparticle-based drug delivery systems have the potential to revolutionize medicine but their low vascular permeability and rapid clearance by phagocytic cells have limited their medical impact. Nanoparticles delivered at the in utero stage have the potential to overcome these key limitations, due to the high rate of angiogenesis and cell division in fetal tissue, and the under-developed immune system. However, very little is known about nanoparticle drug delivery at the fetal stage of development. In this report, using Ai9 CRE reporter mice, we demonstrate that lipid nanoparticle (LNP) mRNA complexes can deliver mRNA for gene editing enzymes in utero after an intrahepatic injection, and can access and edit major organs, such as the heart, the liver, kidneys, lungs and the gastrointestinal tract with remarkable efficiency and low toxicity. In addition, we show here that Cas9 mRNA and sgRNA complexed to LNPs were able to edit the fetal organs in utero after an intrahepatic injection. These experiments demonstrate the possibility of non-viral delivery of gene editing enzymes in utero and nanoparticle drug delivery has great potential for delivering macromolecules to organs outside of the liver in utero, which provides a promising strategy for treating a wide variety of devastating genetic diseases before birth.

Microbiome engineering aims to develop engineered live biotherapeutic products to diagnose and treat human disease. One of the most active areas is in the engineering of modified bacteria that act as cancer therapeutics, with many products currently in clinical trials. With the emergence of any novel technologies, it is important to consult the public and end users throughout their development to address any concerns that may arise from their use. This is particularly true for therapeutics, for which it is vital that both clinicians and patients have confidence in the treatments that are available to them. Here, we surveyed a cohort of cancer patients and their relatives to gauge their knowledge of modern microbiome engineering techniques. We focus predominately on the use of bacterial eLBPs to treat cancer. Overall, most participants indicated that they would be comfortable taking cancer treatment options based on microbiome engineering technologies.

Cooperation in social species is shaped by ongoing social relationships, partner choice, and group interactions, demanding experimental systems that preserve the social context in which these behaviors unfold. Here we introduce the e-Seesaw, a wireless system for automated liquid reward delivery designed to support home-enclosure experiments on reward access distribution in common marmosets (Callithrix jacchus) with minimal human intervention. The apparatus combines a modular peristaltic pump with a Bluetooth-controlled trigger, allowing spatial separation between the site of action and the site of reward delivery while preserving group housing. We provide detailed design files, software, and assembly instructions to support reproduction and adaptation. In a proof-of-concept deployment across seven families, animals readily engaged with the device, producing a median of ~87 trigger activations per session. Engagement was concentrated early within sessions and remained largely stable across repeated deployments, including under increased action-reward separation. These results established the e-Seesaw as a flexible and reproducible platform for automated reward-delivery experiments in animals tested within their social groups, while reducing human involvement and avoiding fixed dyadic testing.

Currently, there is not any method for efficient and targeted delivery of gene therapies using viral vectors to the native kidneys. Adeno-associated viruses (AAV) are limited by hepatotoxicity and poor kidney tropism. This study aimed to develop a minimally invasive approach that overcomes both challenges. We evaluated in pigs a technique leveraging external perfusion systems to transiently isolate native kidney vascularization. Using a percutaneous femoral approach, fluoroscopy-guided catheterization of the kidney artery and vein enabled the establishment of a temporary isolated kidney perfusion circuit permitting native kidney in-situ perfusion. AAV delivery was then assessed by detecting construct encoding Td-Tomato protein, its mRNA and fluorescence 6 days after the perfusion. The method was achieved with two different external perfusion systems and was not associated with procedure related mortality or any major complication. Td-Tomato was detected in the perfused kidney without a significant detection in the liver which showed no inflammatory infiltrates. We developed, in pigs, a minimally invasive method permitting in-situ native kidney perfusion that enables kidney-targeted AAV delivery. Besides, it limits liver off-target transduction, potentially reducing its main side effect, hepatotoxicity, when AAV is systemically injected. It offers fast-track translational possibilities for developing kidney-targeted gene therapies. Finally, it may permit additional non-AAV therapeutics for patients with kidney diseases.

BackgroundThe main strategy to contain the current SARS-CoV-2 pandemic remains to implement a comprehensive testing, tracing and quarantining strategy until vaccination of the population is adequate. MethodsTen dogs were trained to detect SARS-CoV-2 infections in beta-propiolactone inactivated saliva samples. The subsequent cognitive transfer performance for the recognition of non-inactivated samples were tested on saliva, urine, and sweat in a randomised, double-blind controlled study. ResultsDogs were tested on a total of 5242 randomised sample presentations. Dogs detected non-inactivated saliva samples with a diagnostic sensitivity of 84% and specificity of 95%. In a subsequent experiment to compare the scent recognition between the three non-inactivated body fluids, diagnostic sensitivity and specificity were 95% and 98% for urine, 91% and 94% for sweat, 82%, and 96% for saliva respectively. ConclusionsThe scent cognitive transfer performance between inactivated and non-inactivated samples as well as between different sample materials indicates that global, specific SARS-CoV-2-associated volatile compounds are released across different body secretions, independently from the patients symptoms. FundingThe project was funded as a special research project of the German Armed Forces. The funding source DZIF-Fasttrack 1.921 provided us with means for biosampling.

Background/ObjectivesThe integration of large language model (LLM)-based AI tools into veterinary clinical practice is rapidly increasing; however, no systematically derived taxonomy of veterinary AI query patterns has been established. This study aimed to develop and refine an exploratory taxonomy of veterinary AI query patterns across clinical stages through a structured expert-panel review process. MethodsAn exploratory cross-sectional expert panel study was conducted. 5,372 real-world query logs from a veterinary clinical AI chatbot deployed over eight months were analyzed using AI-assisted inductive coding to derive an initial taxonomy. The taxonomy was refined through literature review and subsequently reviewed by an expert panel of 38 veterinary professionals via structured online survey across five clinical stages. ResultsA taxonomy of 3 categories and 21 subtypes was established: Clinical Support Queries (Types A-H), Evidence-Based Research Queries (Types I-L), and Terminology and Drug Reference Queries (Types M-U). Type B (Differential Reasoning) had the highest overall frequency (57/188 first-choice responses), while Type D (Clinical Decision Support) was dominant immediately post-consultation (55.3%). Veterinary professionals with [&ge;]10 years of experience showed a higher frequency of Type G (Evidence Search) preference than those with <10 years of experience (18 vs. 4), while university-affiliated professionals demonstrated a distinct pattern dominated by Type G. ConclusionsTo our knowledge, no published study has previously established a veterinary-specific, clinical-stage-sensitive exploratory taxonomy of AI query patterns; this study addresses that gap. The findings provide a foundational framework for designing context-aware, stage-adaptive veterinary AI systems and benchmark evaluation tools.

The experimental use of antibodies that have not been validated for context-specific use frequently misdirects biomedical research. Experimental results that derive from the use of inadequately validated antibodies are estimated to waste over $1 billion annually in the United States alone and to consume millions of animal and human biological samples in experiments whose conclusions may be unreliable. Community validation frameworks, reporting standards, and independent characterisation initiatives have made important progress, and multi-stakeholder coordination efforts are emerging. However, the research community lacks a formally developed, consensus-based action plan that specifies what each stakeholder group should do, by when, and with what priority. We conducted a modified Delphi study with international experts representing academic researchers, scientific publishers, research funders, antibody manufacturers, and institutional research leaders to develop actionable recommendations for improving antibody validation, selection, and reporting practices. Thirty-two participants rated 33 proposed actions on effectiveness and feasibility using 9-point scales, with consensus assessed using the RAND/UCLA Appropriateness Method. Over two rounds, the panel achieved consensus on 15 items as both effective and feasible for implementation by 2030. These spanned institutional actions (training in antibody validation, integration into research integrity frameworks, support for local expertise networks), funder actions (dedicated validation budgets, grant application requirements, endorsement of community reporting standards), publisher actions (complete antibody reporting packages, clear validation standards), manufacturer actions (assignment of unique identifiers at source), and cross-stakeholder coordination (a shared roadmap for improvement). An additional 15 items were rated as effective but with uncertain feasibility, reflecting a consistent pattern in which the panel agreed on the value of proposed interventions but expressed reservations about realistic implementation timelines. One item was rejected by the panel with concerns around effectiveness and feasibility. Participants described four interconnected barriers to progress: diffuse ownership of the problem across stakeholders; market dynamics that inadequately reward antibody quality; difficulty justifying investment when returns are distributed across the research system; and coordination challenges among actors with different incentive structures. These barriers are addressable through coordinated action, and the findings complement existing technical and data-sharing initiatives by providing the structured, stakeholder-endorsed policy framework needed to translate awareness of the problem into concrete practice and policy changes.

BackgroundLong-term home-cage monitoring is essential to quantify spontaneous locomotor and social behaviors in group-housed mice, but analysis of high-density RFID tracking data remains a barrier to reproducibility. New methodsWe developed IntelliProfiler 2.0, a fully R-based pipeline tailored to the eeeHive 2D floor-mounted RFID array. The workflow performs data import from text logs, preprocessing, coordinate reconstruction, missing-value handling, feature extraction, statistical testing, and visualization in a single environment. Behavioral metrics include travel distance, close contact ratio (CCR), and a newly implemented inter-individual distance metric. ResultsIn four-day recordings of group-housed C57BL/6J mice (8 males and 8 females), IntelliProfiler 2.0 captured circadian phase-dependent locomotion and proximity patterns and reproduced sex-dependent differences consistent with prior analyses while incorporating updated hardware specifications. Radar-chart summaries enabled intuitive comparison of multidimensional behavioral profiles and inter-individual variability across light/dark phases. Comparison with existing methodsCompared with IntelliProfiler 1.0 and multi-tool workflows, IntelliProfiler 2.0 consolidates analysis into a single, script-based R pipeline, reducing operational complexity and improving reproducibility. The updated implementation supports recent manufacturer-driven changes, including antenna renumbering and multi-USB data export. ConclusionsIntelliProfiler 2.0 provides a reproducible, extensible framework for high-throughput behavioral phenotyping of group-housed mice and is scalable across hardware configurations, including simplified single-board recordings. HighlightsO_LIEnd-to-end R pipeline for eeeHive 2D floor-based RFID tracking analysis C_LIO_LIStandardized setup with comprehensive manuals and protocols C_LIO_LIInter-individual distance metric to quantify group spatial structure C_LIO_LICircadian- and sex-dependent behavioral profiling in group-housed mice C_LIO_LIRadar-charts summarize multidimensional behavioral profiles and variability C_LI

Deficits in social motivation are a core feature of many neurodevelopmental disorders, including autism spectrum disorders. While a range of tools have been developed to quantify social motivation in rodents, most rely on brief tests in dedicated apparatuses that can introduce stress and novelty, potentially reducing test reliability. Most current approaches are also typically not suited to studying learning across days or circadian rhythms of social motivation. To address these challenges, we developed a social operant task that can run around-the-clock for multiple days in the mouse homecage, continuously monitoring social motivation around the circadian cycle. The task consists of a custom-built automated door that was installed between two rodent homecages and configured so one mouse could trigger the door to open with a nose-poke action from within their cage. When open, the door allows for social interaction with the neighboring mouse through a perforated stainless-steel panel, which did not allow the mice to cross over into the neighboring cage. Mice opened the door multiple times each day, allowing us to quantify their amount and daily rhythms of social motivation. In our first experiment, C57BL/6J mice (both sexes) were individually housed with an empty adjacent cage for five days, after which a same-sex social partner was introduced for another nine days. Mice opened the door at significantly higher rates when the social partner was present vs. absent, confirming that mice were motivated to earn social interaction. This task also revealed a circadian rhythm to social motivation that peaked about 2 hours after the peak in their feeding rhythm. We speculate that mice first addressed their caloric needs each day before changing their priority to social behavior. Given prior literature implicating the dopamine system in social motivation, we also tested whether dopamine antagonists would block social motivation in our task in a new group of 14 mice (both sexes). The dopamine D1 receptor antagonist SCH23390 (delivered systemically at 0.3mg/kg SC) reduced social seeking without affecting locomotor activity or food intake, demonstrating a selective role for dopamine D1 receptors in social motivation. The dopamine D2 receptor antagonist haloperidol (delivered systemically at 0.3mg/kg SC) also reduced social seeking, but reduced locomotor activity and food intake as well, demonstrating a general reduction in behavior that was not specific to social motivation. Overall, our task offers a way for studying social motivation in the rodent homecage, which has advantages for studying disorders that involve both social and circadian disruptions.

We introduce LeDNA, a versatile educational toolkit designed for teaching fundamental genetics and CRISPR-Cas gene editing principles in diverse settings, regardless of existing infrastructure. Fabricated using laser-cutting techniques, LeDNA is an open-source resource suitable for students across educational levels, from high school to graduate studies. Given the transformative potential of CRISPR technology in various fields, including medicine and agriculture, a widespread understanding of its principles is essential for informed public discourse and acceptance. By providing a readily accessible and affordable tool, LeDNA aims to democratize genetics and CRISPR education globally, fostering a more informed and engaged community.

Handling-induced stress represents a major burden on laboratory mice and is heavily influenced by the handling technique. As such, tail-handling induces much higher stress than cup- or tunnel-handling, which is further aggravated by interventions, e.g. injections, which require even harsher fixation methods. Previous studies demonstrated that habituation protocols can improve animal welfare during handling and interventions. Here, we developed a medical training program and an alternative fixation method using an application tunnel in the context of a liver cancer model, where frequent intraperitoneal injections over many weeks are needed to induce tumor development. The training regimen consisted of 5 sessions over 2 weeks, which gradually introduced the animals to being touched by handlers and restrained for procedures. The training program was completed once before the start of any interventions, additional training sessions were performed biweekly during the entire course of the experiments. The animals were randomized to receive injections either in the novel application tunnel or using conventional fixation. Training effect was continuously monitored by measuring the latency to interact with the experimenter, the surface body temperature and by movement tracking. The latency to interact rapidly decreased during initial training sessions, and this effect was sustained throughout the course of treatment. Movement tracking demonstrated that mice injected inside the tunnel were more active and returned to their normal behavior after injections faster than conventionally restrained mice. Those mice also showed less signs of defecation and urination. Furthermore, the tunnel had a positive influence on the well-being of mice during blood sampling demonstrated by reduced signs of pain and faster willingness to interact with the handler after the procedure. In conclusion, habituation of the mice to the interventions with medical training and the improved handling procedure during ip injections and blood draws durably reduces stress levels and improves welfare of mice.

ABSTRACTBackground &amp; objectives The study had two aims. 1) Analysis of research projects done in our institution from 2014-2019 to identify products with a potential for commercialization and 2) To understand the effect of product-development variables on research projects to improve the quality of future commercialization-oriented trials.Methods 338 clinical trials were grouped into 188 projects under the headings irrigants, diagnostic devices, surgical devices, biomaterials and gels. Trials per project, capital, material costs, labour and the cycle times per trial were calculated. To understand the effect these variables, five hypotheses were generated to test whether greater number of trials, successes, higher capital, more investigators per trial and a longer trial duration will result in a product worthy of commercialization.Results 22 projects had products with a potential for commercialization. Except labour and cycle time (p&gt;0.05), all variables showed significant differences across all projects. Three products were identified as having potential for actual commercialization. It was observed that greater number of trials (χ2=4.6793; p=0.030528) and successes (χ2=20.8134; p&lt;0.00001) in a project along with a higher capital (χ2=12.2662; p=0.000461) will generate a product worthy of commercialization.Interpretation &amp; conclusions The results seem to suggest that in trials for commercialization, emphasis must be placed on implementing multiple, well-designed clinical trials on a device or product to successfully identify whether it is commercialization-worthy or not. Due attention must be given to the financial aspects of the projects as deficiencies may result in negative impact on the flow and outcomes of a clinical trial.Competing Interest StatementThis study is supported by a grant (DST/NSTMIS/05/222/2017-18) under the National Science &amp; Technology Management Information System (NSTMIS), Department of Science and Technology, Government of India. Dr Rama Raju holds a patent on a low-cost oral cancer detection device. Dr R Viswa Chandra has patents pending on a butyrate inactivated recombinant human bone morphogenetic protein-2 (rhBMP-2) gel and basic fibroblast growth factor (bFGF) impregnated collagen membranes. View Full Text

Comprehensive and spatially mapped molecular atlases of organs at a cellular level are a critical resource to gain insights into pathogenic mechanisms and personalized therapies for diseases. The Kidney Precision Medicine Project (KPMP) is an endeavor to generate 3-dimensional (3D) molecular atlases of healthy and diseased kidney biopsies using multiple state-of-the-art OMICS and imaging technologies across several institutions. Obtaining rigorous and reproducible results from disparate methods and at different sites to interrogate biomolecules at a single cell level or in 3D space is a significant challenge that can be a futile exercise if not well controlled. We describe a "follow the tissue" pipeline for generating a reliable and authentic single cell/region 3D molecular atlas of human adult kidney. Our approach emphasizes quality assurance, quality control, validation and harmonization across different OMICS and imaging technologies from sample procurement, processing, storage, shipping to data generation, analysis and sharing. We established benchmarks for quality control, rigor, reproducibility and feasibility across multiple technologies through a pilot experiment using common source tissue that was processed and analyzed at different institutions and different technologies. A peer review system was established to critically review quality control measures and the reproducibility of data generated by each technology before being approved to interrogate clinical biopsy specimens. The process established economizes the use of valuable biopsy tissue for multi-OMICS and imaging analysis with stringent quality control to ensure rigor and reproducibility of results and serves as a model for precision medicine projects across laboratories, institutions and consortia.

Guinea pigs used in our laboratory for cardiac research sometimes exhibit physical abnormalities. These issues may abate or intensify during the time they are housed in our facility. After using a guinea pig for research, experimentalists note the apparent health of an animal based on visible features and/or abnormal electrophysiology of the heart. There was an existing anecdotal observation that the health of the Guinea Pigs, and subsequently the experimental success rate, had a seasonal variation; therefore we sought to determine if there is a time of year in which our guinea pigs are more likely to be perceived as unhealthy, and whether any determined monthly pattern correlates with an experimentalists ability to complete an experimental protocol. An electronic log was created to record the perceived health of the animal and the ability to complete the experiment successfully. Irregular symptoms included, but were not limited to, severe weight or hair loss and irregularities with the heart found post thoracotomy or during baseline electrophysiological recordings of whole-heart preparations. Animals that did not exhibit significant weight or hair loss, or other ailments were considered "healthy". Overall, our results indicate that there are no monthly variations in perceived Hartley Albino guinea pig health or correlations with experimental completion rates, suggesting mild hair or weight loss that is common when shipping animals may not significantly affect the ability to conduct ex vivo whole-heart electrophysiological studies.