Journal Of The American Association For Laboratory Animal Science[JOURNAL]
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200 papers
Pharmacokinetics and Analgesic Efficacy of a Novel Extended-Release Buprenorphine Formulation in Mice.
Yang S, Fry CD, Durham LB … +2 more , Myers DD, Lester PA
J Am Assoc Lab Anim Sci · 2026 Mar · PMID 41833307 · Full text
Long-acting buprenorphine formulations present a remarkable refinement for the care and management of postoperative pain in rodents. We describe here the evaluation of a novel extended-release buprenorphine formulation (...
Long-acting buprenorphine formulations present a remarkable refinement for the care and management of postoperative pain in rodents. We describe here the evaluation of a novel extended-release buprenorphine formulation (Bup ER) for use in laboratory mice. The pharmacokinetics of a single subcutaneous dose of Bup ER (5 mg/kg) were characterized in male and female CD-1 mice at 0.5, 2, 4, 8, 24, 48, 72, 96, 120, and 168 hours postinjection. Plasma buprenorphine concentrations exceeded 1 ng/mL within 0.5 hours and were maintained above this threshold for up to 120 hours postadministration. The analgesic efficacy of Bup ER was assessed using a tail flick thermal nociception assay and a plantar incisional hypersensitivity model. Mice received Bup ER (5 mg/kg SC, once) or saline (subcutaneously, once) prior to tail flick nociception testing or plantar incisional surgery with corresponding mechanical (von Frey) and thermal (Hargreaves) hypersensitivity testing. Tail flick thermal nociception testing for male and female CD-1 mice indicated significant differences in maximum possible effect between Bup ER and saline groups from 0.5 to 96 hours. Mechanical hypersensitivity was not observed in male or female Bup ER-treated groups for up to 96 hours. Although thermal hypersensitivity was observed in male and female mice that received Bup ER, mice presented significantly less thermal hypersensitivity (attenuation) compared with the saline group from 1 to 48 hours. No abnormal clinical observations were appreciated. Gross findings revealed mild erythema or alopecia at the injection site, and 3 mice developed skin ulcerations that were attributed to injection technique where use of small-gauge needles led to administration into the intradermal compared with subcutaneous space. Ulcerative lesions were not observed after procedures to confirm injection site administration were implemented. Bup ER provided effective postoperative analgesia for 48-96 hours in mice and demonstrated an extended plasma concentration profile up to 120 hours for long-acting analgesia.
Maintaining Welfare While Extending Cage-Change Intervals: A Performance-Based Study in IVC-Housed Mice.
Lamacchia AP, Herrmann C, O'Brien KM … +2 more , Cadwell K, Philips BH
J Am Assoc Lab Anim Sci · 2026 Mar · PMID 41806965 · Full text
Most animal facilities schedule regular, time-dependent cage changes to manage the microenvironment within mouse cages. A 2-week cage-change frequency is accepted as the industry standard for individually ventilated cage...
Most animal facilities schedule regular, time-dependent cage changes to manage the microenvironment within mouse cages. A 2-week cage-change frequency is accepted as the industry standard for individually ventilated cages (IVCs). Experiments involving certain enteric viruses may call for longer intervals between full changes to sustain persistent infection. Cage-change frequency is tied to both increases in animal stress and labor costs. Using 8-week-old wild-type C57BL/6J mice housed in IVCs (76.03 sq. in. with approximately 75 air changes per hour), we assessed the ability to extend the full cage-change interval for cages housing either 2 males or 2 females per cage. As an alternative to full cage changes, we also assessed the effect of changing half the bedding every 14 days for cages containing either 2 female, 4 female, or 2 male mice. We monitored microenvironmental parameters (in-cage ammonia, humidity, and temperature) along with visual cleanliness scores, daily health assessments, and histopathology of nasal tissue at study endpoint to determine the maximum acceptable time between full cage changes. We found that both pair-housed males and females could be housed without bedding change for 42 days, reaching exclusion due to soiled bedding accumulation instead of ammonia threshold or animal health concern. Cages with 2 male or 2 female mice that underwent biweekly partial bedding changes could be housed without a complete cage change for 84 days. Cages with 4 female mice on biweekly partial bedding changes maintained appropriate microenvironmental parameters for 62 days. No mice, in any group, exhibited severe histopathologic evidence of ammonia-induced injury or other disease. Our results indicate that, when cage density is reduced or partial bedding changes can be completed, extending the time before full cage change did not exceed predefined action thresholds and did not produce clinically apparent illness or histologic evidence consistent with ammonia-related injury.
Enhancing Rodent Welfare, Cost Savings, and Efficiency: Implementation and Review of Data-Driven Improvements.
Luchins KR, Felgenhauer JL
J Am Assoc Lab Anim Sci · 2026 Mar · PMID 41786625 · Full text
At the University of Chicago, we have implemented multiple practical, data-driven 3Rs (replacement, reduction, refinement) strategies to improve rodent welfare over the past 5 years. As there are limited publications tha...
At the University of Chicago, we have implemented multiple practical, data-driven 3Rs (replacement, reduction, refinement) strategies to improve rodent welfare over the past 5 years. As there are limited publications that outline an institutional approach, this work reviews the enhancements in animal welfare and operational practices implemented in our rodent program, offering a resource and reference for other institutions. These measures encompass the use of environmental health monitoring for both colony and quarantine surveillance and housing modifications, as well as advancements in enrichment, including nesting and structural options, adoption of mouse-preferred bedding substrate, and housing room temperature modifications to better support the thermoregulatory needs of the mice. In addition, we implemented cage change modifications, which include a scent transfer and reduced cage change frequency. Finally, the use of animal handling improvements at our institution includes refined handling techniques and transport cart modifications. Ultimately, we have been successful at improving animal welfare while also implementing cost savings and efficiency improvements.
Determination of Cardiac Troponin I in Guinea Pigs (Cavia porcellus) under Different Restraint Methods and Using a Point-of-Care Assay or Laboratory Analyzer.
Day AL, Santangelo KS, Ozawa SM … +2 more , Brandão J, Sadar MJ
J Am Assoc Lab Anim Sci · 2026 Mar · PMID 41786611 · Full text
Guinea pigs are a commonly used model for laboratory research, as well as being housed in zoological institutions and kept as pets. These animals can develop cardiac disease, and additional diagnostic modalities are need...
Guinea pigs are a commonly used model for laboratory research, as well as being housed in zoological institutions and kept as pets. These animals can develop cardiac disease, and additional diagnostic modalities are needed to help expediently and accurately diagnose it. Cardiac troponin I (cTnI) is a cardiac-specific biomarker associated with myocyte damage. The objectives of this study were to (1) determine the utility of a point-of-care (POC) cTnI assay in guinea pigs via cardiac and skeletal muscle tissue homogenates serially diluted in saline; (2) compare this POC assay to a high-sensitivity assay; and (3) determine the effect of restraint method (awake, isoflurane, and ketamine-xylazine) on cTnI measurements. A total of 45 guinea pigs were used in this study. Homogenates of cardiac muscle produced detectable concentrations of cTnI, while skeletal muscle homogenates did not. There was a significant difference between the POC (cTnI median 0.000 [range 0.000-0.0450] ng/mL) and the high-sensitivity (cTnI 0.025 [range 0.010-0.042] ng/mL) assays, suggesting that the former may require its own reference interval. There were no significant differences detected among the order of treatments (P = 0.66320), the method of restraint (P = 0.2315), or the interaction between the treatments (P = 0.9755); however, there were more nonzero values obtained for cTnI 7 days after anesthesia with ketamine-xylazine. These results suggest that this POC assay may be useful in the detection of cTnI in guinea pigs using a variety of restraint methods, although a high-sensitivity assay is recommended when low concentrations or small variations in concentration need to be detected.
Enhancing Laboratory Animal Welfare through Motivational Training of Facility Personnel: A One Welfare Approach.
Franzoni Ribeiro B, Gomes de Macedo Braga LM, Zaqueu de Lima T … +7 more , Alves Santos LG, Speck da Silva ML, Barbosa Fialho Martins V, de Souza Munhoz LL, Reginato Facciotti P, Dos Santos Martins D, de Azevedo Ruiz VL
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41759942 · Full text
Measuring the effect of laboratory animal facilities employees' motivational training on laboratory animal welfare is essential to study the impact of the human factor on experimental results. To test this, 15 volunteers...
Measuring the effect of laboratory animal facilities employees' motivational training on laboratory animal welfare is essential to study the impact of the human factor on experimental results. To test this, 15 volunteers were initially recruited, with 14 completing the motivational training, and its impact on animal welfare was evaluated in 174 Swiss mice, specifically primiparous pregnant females. The mice were grouped into a control group (n = 90), observed before the motivational training, and a treated group (n = 84), observed immediately after training. Animal welfare was assessed through various measures, including nesting ability, scored from 0 to 5, time to integrate into nest test, and maternal behavior (considering rates of maternal care such as licking/grooming and staying with the pups). Each volunteer's motivational level was evaluated using the Utrecht Work Engagement Scale, PERMA (positive emotion, engagement, relationships, meaning, and accomplishment) Profiler, and The Authentic Happiness Inventory. The motivational training was based on Yale University's course "The Science of Well-Being," the book The How of Happiness, and "Motivation and Action." Results indicated that the methods used to assess mouse welfare might have been influenced by environmental differences at each research center, resulting in a lack of reproducibility. The motivational training effect varied across research centers, suggesting context-dependent outcomes potentially influenced by environmental or institutional factors for nesting scores and maternal behavior tests. However, no effect of motivational training was observed on the time to integrate into nest test, although facility-related differences were significant. The questionnaires revealed improvements in personnel well-being, although the effect on happiness was attenuated in one facility, indicating possible institutional barriers to intervention efficacy.
The Effect of Capromorelin and Extended-Release Buprenorphine on Body Weight in Guinea Pigs (Cavia porcellus).
Silvers JK, Norris SLW, Punger EM … +1 more , Chisty A
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41759941 · Full text
Guinea pigs (Cavia porcellus) are widely used in biomedical research and are sensitive to stress-induced anorexia and weight loss. Buprenorphine extended release (XR) is commonly used for analgesia in laboratory animals...
Guinea pigs (Cavia porcellus) are widely used in biomedical research and are sensitive to stress-induced anorexia and weight loss. Buprenorphine extended release (XR) is commonly used for analgesia in laboratory animals but has been associated with decreased appetite and weight loss. Capromorelin, a ghrelin receptor agonist, is FDA-approved to stimulate appetite in dogs and cats. However, its utility in mitigating opioid-associated weight loss in guinea pigs has not been evaluated. This study's primary objective was to evaluate the effects of capromorelin on body weight in guinea pigs, both independently and in conjunction with buprenorphine XR administration, and whether oral capromorelin mitigates the weight loss associated with buprenorphine administration. A secondary objective was to evaluate habituation to voluntary consumption of an oral delivery puree and continued consumption of the puree with capromorelin added. Forty-eight female guinea pigs were randomized into 4 groups (n = 12/group) in a 2 × 2 factorial design. Animals were acclimated for 5 days to receive oral treatments, and all received either oral capromorelin (5 mg/kg) or sham treatment daily for 3 days, combined with either a single subcutaneous dose of buprenorphine XR (0.48 mg/kg) or saline. Body weights were recorded days -7 through -3 and days 0 through 5. All animals accepted oral treatments without the need for oral gavage. Guinea pigs receiving buprenorphine XR experienced significant weight loss compared with controls and were significantly less likely to return to baseline weight. Capromorelin treatment did not significantly affect weight change, and no interaction between capromorelin and buprenorphine XR was observed. Therefore, capromorelin at 5 mg/kg once a day for 3 days did not mitigate weight loss associated with buprenorphine XR administration in guinea pigs. These findings emphasize the need for species-specific evaluation of appetite stimulants and support the value of extended monitoring following administration of long-acting analgesics.
Efficacy and Pharmacokinetics of 3 Sustained-Release Buprenorphine Formulations in Cairo Spiny Mice (Acomys cahirinus).
Hasler DE, Dunn LM, Fry CD … +3 more , Martin TL, Hish G, Lester PA
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41759919 · Full text
African spiny mice (Acomys spp.) are an emerging animal model for regeneration due to their remarkable healing capabilities. Defining characteristics of these species include fragile skin that sloughs easily and shedding...
African spiny mice (Acomys spp.) are an emerging animal model for regeneration due to their remarkable healing capabilities. Defining characteristics of these species include fragile skin that sloughs easily and shedding of the tail skin when grabbed, making handling and administration of parenteral drugs difficult in conscious animals. In addition, many studies in spiny mice involve painful procedures. To our knowledge, there are no reports regarding analgesia in Acomys spp. This prospective study aimed to assess 3 sustained-release buprenorphine formulations-lipid-bound extended-release buprenorphine (XRB), polymeric sustained-release buprenorphine (SRB), and long-acting transdermal buprenorphine (TB)-in spiny mice. Adult male and female Cairo spiny mice (Acomys cahirinus) were included and administered 1 of the 3 treatments (XRB 3.25 mg/kg, SRB 1 mg/kg, or TB 20 mg/kg). Tail flick assays to assess nociception and terminal blood collection for pharmacokinetic analysis were performed at baseline and a set timepoint following treatment administration (1, 2, 4, 8, 24, 48, and 72 hours) (n = 3 of each sex per timepoint per treatment group). Additional animals underwent repeated serial tail flick assays at 1, 2, 4, 8, 24, 48, and 72 hours following the administration of treatment or sterile saline (n = 5-8 of each sex per treatment group). XRB displayed the longest duration at which mean plasma buprenorphine concentrations were >1 ng/mL, with the drug remaining above this level for 48-72 hours, compared with 24-48 hours in spiny mice receiving TB and 8 hours in those receiving SRB. On serial tail flick assays, the mean percentage of maximum possible efficacy was highest at all timepoints up to 72 hours in the TB group, followed by the XRB group, suggestive of greater analgesic efficacy. Several spiny mice receiving SRB developed ulcerative skin lesions within 24 hours of administration, so this treatment is not recommended in Acomys without additional evaluation. XRB and TB are promising analgesic therapies in spiny mice, and treatment selection should be based on whether duration of action or ease of application is the priority.
Assessing Local Anesthesia in Octopus bimaculoides to Provide Analgesia.
Copio JN, Schulz NG, Ragsdale CW … +5 more , Cerreta AJ, Ostdiek AM, Luchins KR, Langan GP, Mailhiot D
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41759917 · Full text
Despite the substantial growth of cephalopod research over the past 15 years, effective pain management for these animals remains largely unstudied, and no US federal regulations currently address cephalopod analgesia. T...
Despite the substantial growth of cephalopod research over the past 15 years, effective pain management for these animals remains largely unstudied, and no US federal regulations currently address cephalopod analgesia. This 2-phase study evaluated the feasibility and efficacy of lidocaine, bupivacaine, and extended-release bupivacaine injections for producing analgesia in juvenile Octopus bimaculoides in an established model of arm regeneration. Phase I served as a pilot to assess adverse effects, practicality, and histopathologic consequences of drug administration. Forty-nine animals were randomized to the saline control or treatment groups. Phase II assessed lidocaine, bupivacaine, and saline in an additional 34 animals, using behavioral metrics at multiple time points, including a posture and gait analysis during a walking assessment and mechanical allodynia evaluation via the von Frey filament test. Health indicators, such as weight change and respiratory rate, were also monitored. Finally, wound healing and arm regeneration were followed with photo documentation. Although all animals displayed statistically significant changes in arm posture and gait immediately postsurgery, these changes invariably resolved within 72 hours irrespective of treatment group. Moreover, health and regenerative outcomes did not differ significantly among the treatment groups. The failure of local anesthetic efficacy highlights the need for alternative analgesic regimes for octopus research.
Standardizing Perioperative Heat to Improve Mouse (Mus musculus) Recovery.
Popadich AJ, Mishra B, Oldham SN … +5 more , Hwang SK, Luo X, Ramirez JA, Straley EE, Kastenmayer RJ
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41707678 · Full text
Maintaining the core body temperature of anesthetized rodents is essential because of the depression of physiologic homeostasis caused by anesthetics. The maintenance of core body temperature is influenced by the ability...
Maintaining the core body temperature of anesthetized rodents is essential because of the depression of physiologic homeostasis caused by anesthetics. The maintenance of core body temperature is influenced by the ability of the heating device to provide sufficient heat, the presence of material that might alter heat transfer, and the administration of heat in the period surrounding anesthesia. In this study, optimal heat transfer from 4 unique heating devices, with or without insulating drapes, was determined initially with an inert model. Optimal animal recovery, as evaluated by recovery to baseline activity and normothermic temperature of postoperative animals implanted with an intrabdominal thermometer and monitored with a digitally ventilated caging, was achieved by a device that provided consistent electrically supplied heat at 40 °C throughout the perianesthesia period including 35 minutes before isoflurane anesthetic induction. Animals without preoperative heating required at least 24 hours to return to normal core temperature and normal circadian activity levels.
A Comparative Analysis of the Genetic Structures of Rhesus Macaques (Macaca mulatta) Kept in Enclosure-Based Systems and Semi-Natural Settings.
Kanthaswamy S
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41698678 · Full text
This study compares 2 rhesus macaque populations, one captive (the California National Primate Research Center [CNPRC]) and one seminatural (the Cayo Santiago [CS] population), to evaluate the impact of colony management...
This study compares 2 rhesus macaque populations, one captive (the California National Primate Research Center [CNPRC]) and one seminatural (the Cayo Santiago [CS] population), to evaluate the impact of colony management on genetic structure. While the CNPRC houses its 4,000-plus animals in different housing enclosures, CS has a seminatural, free-ranging population of ∼1,900 individuals. Pedigrees of 3,679 animals at the CNPRC and 2,147 animals at CS were analyzed to assess cross-generational genome uniqueness (GU), inbreeding coefficients, mean kinship (MK), founder equivalents, and founder genome equivalents. An estimated 30% of the 409 CS founders contributed to the present population, compared with <10% of the 2,980 founders and subsequently introduced animals at the CNPRC. Differences in pedigree structure and potential inbreeding risk, particularly at the CNPRC, indicate a more genetically subdivided population there than at CS. The CNPRC also exhibited a lower GU than CS, whereas the MK of both colonies showed a similar upward trend over the study period (2000-2024). Also revealed are significant differences in reproductive activity, lifespan, and the number of families per individual between the 2 colonies. There are challenges in maintaining captive-bred colonies, such as the CNPRC, where restricted gene flow and inbreeding lead to dramatic declines in genetic variability. Strategies such as equalizing reproductive success, implementing cross-fostering programs for infants, and introducing new animals are insufficient to combat inbreeding, genetic subdivisions, and the loss of founder representation. Findings highlight the need for ongoing monitoring of inbreeding coefficients, GU, and MK to safeguard genetic integrity and ensure the long-term viability of captive-bred colonies. The analysis also offers insights for managing these colonies, highlighting MK as a key metric for preserving genetic diversity because it integrates founder representation, drift, and inbreeding into a colony-wide measure that directly informs colony management decisions.
Paired versus Single Housing of Ferrets (Mustela putorius furo) Does Not Influence Experimental Outcomes of Influenza A Virus Pathogenesis Studies.
Belser JA, Kieran TJ, Truelove MA … +3 more , Daggett G, Jean SM, Maines TR
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41698665 · Full text
Social housing of animals is well recognized as a fundamental element in providing for the well-being of social animals during laboratory research activities but is contraindicated in some experimental designs. To ascert...
Social housing of animals is well recognized as a fundamental element in providing for the well-being of social animals during laboratory research activities but is contraindicated in some experimental designs. To ascertain if social housing represented a potential confounder in studies determining influenza A virus (IAV) pathogenicity conducted in the ferret model, we analyzed data from ferrets inoculated with 56 distinct IAV strains, where animals were housed either singly or in pairs postinoculation. Parameters examined included frequency of lethal outcomes, timing and magnitude of clinical signs (weight loss and fever), and magnitude and kinetics of viral shedding in the upper respiratory tract. Statistical differences between IAV-inoculated ferrets housed in either setting were not consistently detected among any parameters examined, supporting that data from ferrets inoculated with a diverse range of avian- and mammalian-origin IAV housed singly or in social pairs may be combined and analyzed without confounding based on this variable. This study supports the utility of performing retrospective analyses to ensure results obtained from in vivo experimentation are interpreted to the highest standard possible. Further, it aligns with ethical obligations of researchers who perform in vivo experimentation to ensure these studies are designed to meet both animal welfare considerations and research goals.
Analysis of Gross and Histopathologic Changes from Repeated Celiotomies in African Clawed Frogs (Xenopus laevis).
Mailhiot D, Turcios R, Remmers G … +5 more , Brazzell J, Langan GP, Clancy BM, Kries K, Luchins KR
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41692417 · Full text
Repeated survival surgical oocyte collection in African clawed frogs (Xenopus laevis) is commonly performed to access high-quality, viable oocytes for research procedures and to reduce the number of animals used in resea...
Repeated survival surgical oocyte collection in African clawed frogs (Xenopus laevis) is commonly performed to access high-quality, viable oocytes for research procedures and to reduce the number of animals used in research. Despite this common practice, there is no evidence-based limit for the total number of survival celiotomies that can be performed. To provide an improved reference, a retired colony of experimental frogs (n = 31) was euthanized for gross and histopathologic evaluation and then compared with 4 experimentally naive age-matched controls (n = 4). Experimental animals underwent 4-11 celiotomies (average 6 ± 2) and were between 180 and 1,646 days (average 448 ± 245.2 days) from their last surgery. Body weight, residual skin, and coelomic wall sutures were counted. Surgically incised skin and coelomic wall musculature were collected for histopathology. A cumulative skin score and a coelomic wall score were developed to reflect all histopathologic evidence of acute and chronic inflammation. The cumulative skin score was significantly predicted by the number of surgeries (P = 0.003), but not predicted by the number of skin sutures remaining (P = 0.14). The coelomic wall score was significantly predicted by the number of coelomic sutures placed (P < 0.001) and the number of surgeries (P < 0.001). Neither one of the histopathology scores correlated to the number of days since the last surgery (P > 0.2). As one would expect, increasing the number of surgeries and coelomic sutures correlated with the histopathologic finding of a chronic inflammatory process in the skin. Although a specific recommendation for a maximum number of surgeries could not be discerned, this study provides an improved reference for Xenopus survival surgical oocyte collection underscoring the recommendation to use absorbable sutures within the body cavity and to remove all external nonabsorbable sutures 10-14 days postoperatively.
Cuprizone in Peanut Butter: An Alternative Method of Cuprizone Administration to Model Demyelination of the Central Nervous System.
Hawker B, Chiddicks E, Flanagan J … +2 more , Connor B, McCaughey-Chapman A
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41692411 · Full text
Modeling disease in rodents is essential for preclinical research, particularly in the development of drugs and therapies. Traditional disease modeling approaches often rely on invasive and stressful procedures such as r...
Modeling disease in rodents is essential for preclinical research, particularly in the development of drugs and therapies. Traditional disease modeling approaches often rely on invasive and stressful procedures such as repeated injections and/or surgical approaches. These methods raise welfare concerns and can introduce stress-related variables that compromise model reliability. Cuprizone (CPZ) is a copper-chelating compound widely used to induce CNS demyelination in mice over a 6-week period via incorporation into ground rodent chow. However, the presumed adverse taste of CPZ reduces food intake, resulting in weight loss, inconsistent consumption, and variable levels of demyelination, complicating disease comparison. To address this, we proposed that mixing CPZ into peanut butter (CPZ-PB) would promote voluntary intake, standardize daily dosing, and minimize weight loss, while maintaining effective demyelination. Thirty mice were divided into control, CPZ-PB, or CPZ-chow groups and received treatment daily for 6 weeks. Body weight and CPZ intake were recorded daily. The effect of demyelination through mechanical allodynia was assessed via the dynamic plantar aesthesiometer. Immunohistochemical analysis of myelin proteins and astrocyte activation was conducted on the brain and spinal cord after 6 weeks of treatment. Voluntary consumption of CPZ-PB successfully ameliorated weight loss concerns and achieved consistent daily CPZ dosing. Behavioral and immunohistochemical analyses confirmed effective demyelination comparable to traditional CPZ-chow methods. This study introduces an improved CPZ administration strategy that enhances animal welfare and provides a more reliable model for demyelination research.
Pharmacokinetics and Paw Withdraw Pressure in Guinea Pigs (Cavia porcellus) Treated with Transdermal Buprenorphine.
Kozlov S, Guerrero-Martin SM, Payne G … +1 more , Kendall LV
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41692410 · Full text
The use of effective analgesia is a cornerstone of laboratory animal care, one that minimizes pain and distress while optimizing care and welfare. Guinea pigs are often used in biomedical research requiring appropriate p...
The use of effective analgesia is a cornerstone of laboratory animal care, one that minimizes pain and distress while optimizing care and welfare. Guinea pigs are often used in biomedical research requiring appropriate pain management. In this study, we evaluated the pharmacokinetics and efficacy of transdermal buprenorphine (Zorbium), a commercial product labeled for use in cats. Guinea pigs (n = 12) received a transdermal dose of buprenorphine (2.7 mg per guinea pig), an average dose of 3.4 mg/kg, applied topically to the interscapular area. Plasma concentration, paw withdraw pressure (PWP) response, sedation scores, and body temperature were collected at 0, 0.25, 0.5, 1, 2, 4, 8, 12, 24, 48, 96, and 120 hours after application. Plasma concentrations peaked at 77.8 ng/mL at 1 hour and remained greater than the targeted 1.0 ng/mL for up to 120 hours, with a half-life of 46.7 hours. PWP peaked at 24 hours with 671.2 g of pressure, remained elevated through 48 hours at 364 g, and returned to baseline by 72 hours. Sedation scores (posture, ambulation, resistance to handling) were slightly elevated at 12 hours, body weight did not significantly change, and rectal temperatures remained normal at all time points. These results suggest that transdermal buprenorphine maintains a prolonged therapeutic plasma level and is an effective analgesic for up to 48 hours in guinea pigs, with minimal side effects. This formulation is an alternative to other buprenorphine formulations that would require less handling for guinea pigs.
A Single-Operator Jugular Vein Sampling Method for Repeated Blood Collection in Conscious Rats.
Wang M, Deng J, Wen Y … +4 more , Xue Y, Xie Y, Jin Y, Li J
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41654039 · Full text
Jugular vein (JV) blood sampling is widely employed in pharmacological, toxicological, and pharmacokinetic studies due to its ability to provide large and repeatable blood volumes. However, current approaches are constra...
Jugular vein (JV) blood sampling is widely employed in pharmacological, toxicological, and pharmacokinetic studies due to its ability to provide large and repeatable blood volumes. However, current approaches are constrained by low convenience, safety concerns, and variable sample quality. Here, we report the development of a new single-operator JV blood sampling technique for conscious rats. By optimizing animal restraint, puncture site localization, and procedural standardization, the method significantly reduced sampling time, puncture attempts, pain-related behaviors, and hemorrhagic injury, while ensuring consistent blood yield. Compared with the conventional approach, it achieved a 100% success rate, halved the average sampling time, and maintained stable serum biochemical, coagulation, and hematologic parameters. The utility of this method was further confirmed in an intraperitoneal glucose tolerance test and a cisplatin-induced acute kidney injury model, where data consistency was preserved. This technique provides a convenient, safe, and reliable alternative for repeated blood collection in conscious rats, ensuring animal welfare and supporting the generation of high-quality data in preclinical research.
A Pharmacokinetic and Efficacy Study of FDA-Indexed Pharmaceutical-Grade Extended-Release Buprenorphine and Compounded Sustained-Release Buprenorphine in African Green Monkeys (Chlorocebus aethiops).
Brown TJ, Rudd T, diTargiani RC … +6 more , Langston JL, Myers TM, Ramos-Rivera E, Riddle LE, Field AE, McCarren H
J Am Assoc Lab Anim Sci · 2026 Feb · PMID 41638613 · Full text
Compounded sustained-release buprenorphine (SRB) has historically been used at our institution for postoperative analgesia in African green monkeys (AGMs), but it is not FDA approved and lacks species-specific data. With...
Compounded sustained-release buprenorphine (SRB) has historically been used at our institution for postoperative analgesia in African green monkeys (AGMs), but it is not FDA approved and lacks species-specific data. With the recent FDA indexing of pharmaceutical-grade extended-release buprenorphine (EXR; Ethiqa XR; Fidelis), we aimed to compare the pharmacokinetic (PK) profile using serial plasma sampling up to 96 hours and postoperative analgesic efficacy of EXR compared with SRB. A total of 10 AGMs (n = 5 per test article) received 0.2 mg/kg SC of either EXR or SRB to complete the PK study. For the efficacy study, 20 animals (n = 10 per test article) were monitored for 3 days postoperatively after EEG telemetry surgery with femoral artery catheterization for behavioral indicators of pain and adverse effects. Plasma buprenorphine levels were analyzed using liquid chromatography-tandem mass spectrometry. PK study observations included appetite, fecal output, and injection site reactions. Both formulations achieved plasma concentrations above the presumed therapeutic threshold (0.1 ng/mL) for up to 96 hours. SRB produced higher mean plasma levels at early time points (30 minutes, 4 hours), but the overall PK profiles were similar. Injection site reactions were minimal and resolved spontaneously. For the efficacy assessment, clinical observations were evaluated using a postoperative score sheet. No significant differences were observed in postoperative pain scores between groups. Both EXR and SRB at 0.2 mg/kg SC provided sustained therapeutic plasma levels up to 96 hours and were well tolerated in AGMs, with comparable efficacy in postoperative pain control. EXR offers a compliant and effective alternative to compounded SRB for analgesia in AGMs, supporting its use in laboratory settings and regulatory compliance with current guidelines.
Subcutaneous Cervical Mass in the Northern Tree Shrew (Tupaia belangeri).
O'Brien KM, Freeman LE, Esannason Munroe KD … +1 more , Gardiner KL
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41628911 · Full text
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Evaluating the Impact of Prophylactic Administration of Ivermectin on the Fecal Microbiome of Healthy C57BL/6J Mice (Mus musculus).
Pope CE, Jones RM, Rashied AA … +2 more , Nagy T, Hanson WH
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41620213 · Full text
Upon importation, laboratory mice may undergo prophylactic antiparasitic treatment during quarantine to prevent the introduction of parasites into established colonies. While quarantine protocols vary across institutions...
Upon importation, laboratory mice may undergo prophylactic antiparasitic treatment during quarantine to prevent the introduction of parasites into established colonies. While quarantine protocols vary across institutions, ivermectin is commonly used, administered either orally or topically. However, the impact of these practices on the fecal microbiome remains poorly understood, raising concerns about unintended consequences for experimental outcomes. This study investigated the effects of ivermectin on fecal microbiome composition in naïve, healthy male and female C57BL/6J mice. Animals received either ivermectin-impregnated feed (12 ppm, ad libitum for 4 weeks), weekly topical ivermectin solution (2.0 mg/kg for 4 weeks), or no treatment (controls). Fecal samples were collected for 16S rRNA-based microbiome analysis before ivermectin treatment, immediately posttreatment, and 4 weeks after treatment cessation. Weekly body weights were recorded, and histopathologic evaluation of the small intestine and colon was performed at study completion. Both oral and topical ivermectin treatments resulted in significant alterations in microbiome α and β diversity at the end of treatment, with more pronounced effects observed in female mice. Some of these changes persisted for up to 4 weeks after treatment cessation. Furthermore, the findings indicate a sex-specific effect of ivermectin on specific bacterial orders, with Bacillales predominantly affected in male mice, whereas Coriobacteriales and Bacteriodales were primarily impacted in female mice. During treatment, males receiving topical ivermectin weighed significantly less than controls, while females receiving dietary ivermectin weighed significantly more. Histopathological analysis revealed no abnormalities in intestinal tissues across all groups at 4 weeks posttreatment. These findings demonstrate that ivermectin administration induces measurable and persistent changes in the fecal microbiome of healthy mice. Researchers should consider these effects when designing experiments, and institutions must weigh the benefits of colony protection against potential microbiome-related confounding variables.
The Shifting Role of the Laboratory Animal Veterinarian: An Emerging Concern.
Basso MA, Gardiner KL, Tansey G … +2 more , Tremblay S, Winterborn A
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41620212 · Full text
The human-animal relationship is undergoing a profound cultural shift, reshaping how societies-and professionals-understand animal welfare. In biomedical research, these changing attitudes have begun to influence the rol...
The human-animal relationship is undergoing a profound cultural shift, reshaping how societies-and professionals-understand animal welfare. In biomedical research, these changing attitudes have begun to influence the role of laboratory animal veterinarians, whose work now sits at the intersection of care, ethics, and compliance. While compassion-driven caution is laudable, the growing tendency toward moral gatekeeping risks impeding ethically justified science. This piece argues for renewed partnership between veterinarians and scientists grounded in evidence, trust, and shared responsibility. Sustaining both animal welfare and scientific progress requires not greater division, but deliberate collaboration-anchored in the belief that ethical research involving animals is a moral good.
Design and Validation of an Arduino-Based, Cost-Effective Heated Anesthesia Induction Chamber for Mice.
Corea A, Tucker K, Benites CE … +2 more , Arellano C, Celdran-Bonafonte D
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41620211 · Full text
Rodents are highly susceptible to peri-anesthetic hypothermia because of their small body size, large surface area to volume/mass ratio, and anesthetic-induced thermoregulatory depression. Early heat loss during inductio...
Rodents are highly susceptible to peri-anesthetic hypothermia because of their small body size, large surface area to volume/mass ratio, and anesthetic-induced thermoregulatory depression. Early heat loss during induction is rapid and can be difficult to reverse, emphasizing the need for simple, reliable warming solutions during anesthetic induction. We designed and validated a low-cost, Arduino-controlled heated induction chamber for mice and evaluated its safety and efficacy in preventing early hypothermia. The device uses proportional integral derivative control to regulate a heated chamber floor. Bench testing quantified warm-up time, steady-state stability, and the temperature offset between the embedded thermistor and surface temperature. In a randomized, paired, repeated-measures design, 10 adult C57BL/6 mice underwent 2 experimental conditions, unheated induction compared with heated induction, followed by a standardized 10-minute anesthetic maintenance phase on a prewarmed, heated surgical monitoring platform. Core body temperature was measured with intraperitoneal radio frequency identification transponders, while rectal temperature and physiologic parameters (peripheral oxygen saturation, heart rate, respiratory rate) were recorded during maintenance. Recovery time was measured from isoflurane discontinuation until the first voluntary movement. The heated chamber reached thermal stability within 10 minutes; at steady state, a constant average surface temperature near 37.5 °C was reliably obtained. During induction, unheated controls showed a rapid decline in core temperature, while during the heated-chamber induction, they maintained normothermia. The control group did not regain baseline temperature until several minutes into the maintenance phase and stabilized at values ∼1 °C lower than those of the heated group. Both groups remained physiologically stable during anesthetic maintenance and recovered within comparable times. This cost-effective, Arduino-based chamber prevented early hypothermia without compromising physiologic stability and represents a practical refinement to improve rodent anesthetic procedures, animal welfare, and experimental reproducibility.
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