Journal Of The American Association For Laboratory Animal Science[JOURNAL]
Sun
200 papers
Effects of Cage Change and Nest Transfer on Artificial Intelligence-Measured Behaviors in Male C57BL/6 Mice.
Kizielewicz N, Molk D, Camacho J … +2 more , Thuman D, Beale C
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41580214 · Full text
Cage changes can be a stressful period in a mouse's life due to the rapid change of environment. It is essential to study the behavioral effects of a cage change on mice, including drinking, eating, aggression, and sleep...
Cage changes can be a stressful period in a mouse's life due to the rapid change of environment. It is essential to study the behavioral effects of a cage change on mice, including drinking, eating, aggression, and sleep, as these can affect research variability. This study evaluated the effects of a cage change on behavior and whether transferring nesting material could mitigate the negative effects of a cage change. Using home cage monitoring with computer vision artificial intelligence, 40 C57BL/6 mice were continuously monitored for 2 consecutive cage changes. Mice received either new nesting material (control) or transferred soiled nesting material at cage change. Data were analyzed before and after a cage change and reported for at least 3 days or until baseline behavior resumed. Parameters collected included time spent drinking, eating, sleeping, and aggression. Two hours after a cage change, drinking and eating significantly increased, and sleep significantly decreased compared with pre-cage change values. Long-term effects ranged from decreased sleep in the first 24 hours to decreased eating for 3 days post-cage change. Total distance traveled was increased up to day 4 post-cage change, and rearing time was increased for 3 days after a cage change. All significant behaviors gradually stabilized by day 5. Transfer of old nesting material had no significant impact at any time point. These results show that there are both long-term and short-term effects of a cage change, and nest transfer may not influence these parameters in C57BL/6 mice.
Total Intravenous Anesthesia with Propofol Effectively Provides a Light Anesthesia Plane in Cynomolgus Male Monkeys (Macaca fascicularis) Undergoing Nociceptive Heat Stimulation.
Zhang M, Schwartz K, Klukinov M … +9 more , Fisher KM, Darian-Smith C, Franco B, Crowley M, Huss M, Sharp P, Jampachaisri K, Yeomans DC, Pacharinsak C
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41564898 · Full text
Limited information exists regarding propofol's use as a total intravenous anesthesia in cynomolgus monkeys. This study investigated the continuous rate infusion (CRI) of propofol to provide light anesthesia during nocic...
Limited information exists regarding propofol's use as a total intravenous anesthesia in cynomolgus monkeys. This study investigated the continuous rate infusion (CRI) of propofol to provide light anesthesia during nociceptive testing. We hypothesized that a CRI of propofol would effectively induce light anesthesia in cynomolgus macaques during repeated weeks of C-fiber nociceptive (heat) stimulation. Four male cynomolgus monkeys were anesthetized with ketamine/dexmedetomidine (4 and 0.02 mg/kg, respectively, IM). Following intravenous catheter placement, atipamezole (0.5 mg/kg SC) was administered to reverse the effect of dexmedetomidine, and a propofol CRI (8-16 mg/kg/h) was initiated. Physiologic parameters, including systolic, diastolic, and mean arterial pressure, heart rate, respiratory rate, peripheral oxygen saturation, and body temperature, were recorded continuously. Animals were maintained with 100% oxygen via a mask and an intravenous electrolyte (Normosol-R; 5-10 mL/kg/h) infusion. Two hours after ketamine/dexmedetomidine administration, propofol doses were incrementally adjusted to elicit withdrawal reflexes using argon laser nociceptive (heat) stimulation (on digital pads of the forearms) with 5- to 15-minute intervals between stimulations. Propofol doses and physiologic parameters were recorded every 15 minutes. Following the baseline testing, the animals underwent a surgical procedure between sessions 1 and 2. Anesthesia and nociceptive stimulation were conducted over 6 nonconsecutive weeks. Test results showed that over the 6-week period the propofol doses remained unchanged, with variations not reaching statistical significance, and the physiologic parameters did not exhibit significant differences. These findings suggest that a propofol CRI of 8 to 16 mg/kg/h effectively provides light anesthesia in cynomolgus macaques during repeated nociceptive (heat) stimulation.
Assessing Ethiqa XR Sterility Past the "Beyond-Discard Date" Under Conditions of Maximum Usage.
Vorwerk H, Moody L, Singh B
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41564897 · Full text
Ethiqa XR is an FDA-indexed, extended-release, lipid-bound buprenorphine formulation providing 72 hours of opioid analgesia with a 90-day postbroach discard date. For small rodent studies, the standard vial frequently pr...
Ethiqa XR is an FDA-indexed, extended-release, lipid-bound buprenorphine formulation providing 72 hours of opioid analgesia with a 90-day postbroach discard date. For small rodent studies, the standard vial frequently provides more drug than can be used within the 90-day labeled discard date, which can limit cost-effectiveness for researchers. This study evaluated whether sterility could be preserved for an additional 90 days beyond the labeled discard date through monthly testing for bacterial and fungal contamination, in addition to the presence of endotoxins. Twice weekly, each vial was wiped with 70% isopropyl alcohol, and a 20-gauge needle was inserted and then withdrawn, with samples removed from the vials at time points up to 180 days. All vials consistently remained free of bacterial, fungal, and endotoxin contamination throughout the study period and were sterile up to the final assessment at 180 days postbroaching. The concentration or efficacy of Ethiqa XR were not evaluated during this study.
Rehoming Laboratory Rats: Exploring Perceptions of Rehomers, Animal Technicians, and Biomedical Researchers.
Greenan G, Quigley C, Vinuela-Fernandez I … +1 more , Menzies J
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41519500 · Full text
Humans work with animals in many different ways. In some contexts, animals are allowed to 'retire' and be rehomed in sanctuaries or private homes when they are no longer able or needed to work. Similarly, laboratory anim...
Humans work with animals in many different ways. In some contexts, animals are allowed to 'retire' and be rehomed in sanctuaries or private homes when they are no longer able or needed to work. Similarly, laboratory animals can be rehomed at the end of a study. However, there is relatively little research on stakeholders' perceptions of rehoming. We explored the views of three key groups: the people who adopt these animals, the animal technicians who care for these animals prior to rehoming, and the researchers who are normally responsible for most of the interactions between people and these animals. To do this, we carried out a thematic analysis of semistructured interviews. Our aim was to obtain insights that could inform reflection and guide future research priorities around rehoming programs. Our study demonstrated support for laboratory rat rehoming in all stakeholder groups. Rehomers' and technicians' comments focused chiefly on the potential benefits of rehoming to the animal and benefits to institutional openness. Researchers made similar comments, but these were tempered by concerns around the welfare of the animals after rehoming, the fate of animals that cannot be rehomed, rehomers' health and wellbeing, and the potential risks associated with the transparency of individual's and the institution's use of animals in research. We discuss these themes in the context of the ethics of laboratory animal use, manifesting a culture of care, and challenges around enhancing institutional openness on animal research.
Social Housing of Postoperative Animals to Support Animal Welfare.
Darbyshire A, Beninson J, Dyson MC … +10 more , Ferguson L, Freebersyser J, McFadden M, Mitchell J, Petervary N, Pritt S, Stokes WS, Taylor JM, Vemulapalli TH, Pritchett-Corning KR
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41500529 · Full text
Single housing of animals, or social isolation, is a known stressor for many species. Generally, laboratory animals are housed in social groups as a default to support their behavioral welfare. In some research protocols...
Single housing of animals, or social isolation, is a known stressor for many species. Generally, laboratory animals are housed in social groups as a default to support their behavioral welfare. In some research protocols, investigators may request exemptions from social housing policies after surgical procedures due to concerns that cohoused animals may damage implanted devices, remove each other's wound closures, or cause other stress or injury that may interfere with the study. However, the practice of singly housing postoperative animals may result in greater stress for animals and unintended consequences for research being conducted. Therefore, the IACUC or relevant ethical body should judiciously consider any request for single housing and require adequate justification for making this exception. This review discusses the social nature of some common research animals, the research effects of single housing, the regulatory requirements for social housing, and successful cases of socially housing postoperative and/or instrumented animals in the research setting with the goal of promoting social housing of postoperative animals.
Prevalence of Large Academic Research Institutions and NCI Designated Cancer Centers with Corynebacterium bovis Infections among Immunodeficient Mice in the United States from 2015 to 2023.
Haverkate MR, Deb A, Fink MK … +5 more , Habenicht LM, Derek FL, Nicklawsky AG, Leszczynski JK, Manuel CA
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41500527 · Full text
Corynebacterium bovis is an opportunistic bacterium that infects the skin of immunodeficient mice used in biomedical research. C. bovis was first deemed clinically significant in the mid-1990s. To date, only limited data...
Corynebacterium bovis is an opportunistic bacterium that infects the skin of immunodeficient mice used in biomedical research. C. bovis was first deemed clinically significant in the mid-1990s. To date, only limited data are available on the prevalence of this infection among research institutions in the United States. Here we define prevalence as the proportion of institutions that have C. bovis-infected mice in their care. To determine the national prevalence of C. bovis infections, we performed a survey of animal resource program directors and veterinarians at the NIH top 50 funded academic institutions and all Designated Cancer Centers of the National Cancer Institute. This survey was initially performed in 2015 and then expanded and repeated in 2023. Survey questions assessed institutional C. bovis status (positive, negative, or unsure), surveillance practices, and attempts to establish C. bovis-free colonies through bioexclusion. Responses were obtained from 81 institutions in 2015 and 85 in 2023, achieving 100% participation in both years. Between 2015 and 2023, C. bovis-positive status declined slightly (49% to 45%), negative responses dropped more sharply (38% to 22%), and uncertainty increased (12% to 33%), resulting in an overall shift in response distribution (P = 0.002). Despite the increased uncertainty, 69% (59/85) of all institutions in 2023 performed active surveillance for C. bovis in some form. Similarly, of institutions that self-report as having C. bovis-infected mice, 84.2% (32/38) performed C. bovis surveillance, and 78.9% (30/38) have used bioexclusion techniques. Overall, 71.7% (61/85) of institutions recognize C. bovis as an actionable pathogen. Conversely, between 20% and 28% (17 and 24/85) of institutions in 2023 did not see C. bovis as an actionable pathogen and, if present, chose to tolerate it.
Effects of Scruff Restraint and Handling-Tail and Tunnel-on Plasma Corticosterone in Female BALB/c Mice (Mus musculus).
Otsuka J, Wagai G, Togao M … +3 more , Ohta-Takada Y, Ando M, Kawakami K
J Am Assoc Lab Anim Sci · 2026 Jan · PMID 41500526 · Full text
Tunnel handling is a widely recommended, less-aversive method for improving laboratory mouse welfare by reducing handling-induced anxiety. While its effects on behavioral tests and physiologic outcomes have been reported...
Tunnel handling is a widely recommended, less-aversive method for improving laboratory mouse welfare by reducing handling-induced anxiety. While its effects on behavioral tests and physiologic outcomes have been reported, little is known about its impact on stress responses to brief restraint procedures commonly used in daily health checks and experimental work. This study aimed to investigate whether tunnel or tail handling influences the physiologic stress response of mice following a brief scruff restraint. Female BALB/c mice were assigned to one of 4 groups combining 2 handling methods (tail or tunnel) with or without a 10-second scruff restraint. Both single and repeated restraint procedures were evaluated separately. Voluntary interaction with the handling device was used to assess the suitability of the handling method. Plasma corticosterone (pCORT) concentrations were measured 20 minutes after restraint to evaluate the physiologic stress response. Tunnel-handled mice showed longer voluntary interaction times than tail-handled mice, indicating reduced handling aversion. Scruff restraint increased pCORT concentrations in both tail- and tunnel-handled mice. However, the handling method did not significantly affect pCORT concentrations following either single or repeated restraint. These findings suggest that the handling method has minimal impact on physiologic stress following brief restraint, supporting the use of less-aversive handling techniques without concern for confounding stress effects.
Myocardial Fibrosis Caused by Angiotensin II Implant in Rabbit Atherosclerosis Model Induced by High Cholesterol Diet.
Gomes D, Kizielewicz N, Morris J … +7 more , Beale C, Mauskapf A, Jaffer FA, Miller AD, Gu JY, Lester P, Yang J
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41468979 · Full text
Rabbits are widely used in biomedical research as models for atherosclerosis with disease induction achieved through a high-cholesterol diet, transgenic approaches, or spontaneous development with aging. At our instituti...
Rabbits are widely used in biomedical research as models for atherosclerosis with disease induction achieved through a high-cholesterol diet, transgenic approaches, or spontaneous development with aging. At our institution, New Zealand White rabbits were induced to develop atherosclerosis via a high-cholesterol diet followed by arterial balloon injury. This model was established to support intravascular molecular imaging studies aimed at tracking atheromatous plaque progression in vivo. To accelerate plaque development, a subcutaneous osmotic pump delivering angiotensin II at 50 ng/kg/min was implanted. While this method enhanced disease progression, unexpected clinical complications were observed. In this retrospective case report, we reviewed clinical records from 54 rabbits over a 2-year period. Clinically, most study animals showed different levels of inappetence. Three presented respiratory symptoms including cyanosis, dyspnea, or tachypnea, while another 3 exhibited neurologic signs such as altered mentation and paralysis. Eight rabbits (14.8%) were euthanized due to severe clinical signs. Necropsy findings in the affected animals commonly revealed pleural and/or peritoneal effusion; one case included chyloabdomen, a condition not previously reported in rabbits. Of these, 7 had myocardial degeneration and fibrosis. These findings suggest that angiotensin II infusion in this rabbit model of atherosclerosis may induce myocardial fibrosis as a significant adverse effect. This report highlights potential complications associated with the model and provides guidance for clinical monitoring, diagnosis, and management in future studies.
Decidual Cell Reaction and Endometritis in a Guinea Pig.
Gozalo AS, St Claire MC, Elkins WR
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41468976 · Full text
A female, research-naive, strain 13 guinea pig with no previous significant health history was noted to have a persistent vaginal discharge. On physical examination a soft mass was noted in the lower abdomen accompanied...
A female, research-naive, strain 13 guinea pig with no previous significant health history was noted to have a persistent vaginal discharge. On physical examination a soft mass was noted in the lower abdomen accompanied by a serosanguineous vaginal discharge. Due to a poor prognosis, the animal was euthanized. At necropsy, the left uterine horn was markedly enlarged and contained a large amorphous mass. Light microscopy examination showed that the mass had dense areas containing stromal cells surrounded by connective tissue, congested blood vessels, areas of necrosis, hemorrhage, and occasional cyst formation. In some areas numerous bacteria, both rods and cocci, were noted and the uterine wall showed increased thickness caused by a polymorphonuclear cell inflammatory infiltrate. Bacteriological culture and isolation from the vaginal discharge revealed a mixed infection with Escherichia coli, Bacteroides fragilis, Proteus mirabilis, Enterococcus spp., and α-hemolytic Streptococcus spp. while culture and isolation from the uterus revealed a mixed infection with E. coli, Pseudomonas aeruginosa, B. fragilis, and Globicatella sanguinis. The pathology findings were consistent with decidual cell reaction and endometritis. Vaginal bleeding is not a common clinical sign in decidual cell reaction and usually does not require treatment since the lesion in many cases resolves on its own by apoptosis and resorption. However, in this case, systemic antibiotics may have been beneficial to treat the endometrial infection. These findings suggest that decidual cell reactions may occur accompanied by, or as a result of, intrauterine infections in guinea pigs. The potential role of bacteria in decidual cell reaction should be further explored in guinea pigs.
Case Report: Malignant Interstitial Cell Tumor with Pulmonary Metastases in an Aging Naïve Fischer 344 Rat.
Reineking W, Schwartz K, Mocarski E … +1 more , Vilches-Moure JG
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41456862 · Full text
Fischer 344 rats are a well-characterized laboratory animal. Of note, their popularity as a research model declined due to the high incidence of spontaneous tumor development in the strain. Among these tumors, testicular...
Fischer 344 rats are a well-characterized laboratory animal. Of note, their popularity as a research model declined due to the high incidence of spontaneous tumor development in the strain. Among these tumors, testicular interstitial cell tumors (ICTs) are frequently observed. We describe here three aged male Fischer 344 rats that were submitted for diagnostic pathology due to an increase in morbidity (increased respiratory effort, general malaise, and weight loss) in the research cohort. In all animals, there was bilateral enlargement of the testes. On the cut surface, multiple well-demarcated masses were compressing and replacing the original testicular tissue. Histologically, these masses were identified as ICTs. The tumors were composed of 3 distinct cell types that correlate with varying degrees of interstitial cell maturation. In one rat, intravascular pulmonary metastases were observed, which resembled the ICT cells morphologically. Malignant ICTs are an unusual finding despite the very high incidence of ICTs in Fischer 344 rats. Our assessment suggests that there are no morphologic criteria that reliably predict malignant and metastatic behavior of ICTs in F344 rats, highlighting the need for clinical monitoring of animals for which castration is chosen as a treatment.
Gastrointestinal Intraluminal pH of Non-Fasted Mice (Mus musculus) of Various Strains and Vendors Including Germ-Free and Streptomycin-Treated Mice.
Jensen FCA, Birch JS, Gram A … +2 more , Hansen CHF, Nielsen DS
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41448591 · Full text
Mice are a valuable tool for preclinical research, enabling the investigation of fundamental questions about disease mechanisms, drug delivery, and pharmacokinetics. Intestinal pH influences drug delivery and pharmacokin...
Mice are a valuable tool for preclinical research, enabling the investigation of fundamental questions about disease mechanisms, drug delivery, and pharmacokinetics. Intestinal pH influences drug delivery and pharmacokinetics of orally administered compounds. However, little is known about variations in pH along different sections of the mouse gastrointestinal tract. We therefore compared pH in 7 gastrointestinal tract sections of 48 male and female BALB/c, C57BL/6, and NMRI mice from 2 different vendors, as well as 8 streptomycin-treated and 8 germ-free BALB/c male and female mice from one vendor. The pH in the duodenum and cecum varied between strains and vendors. Relative to untreated barrier-bred mice, streptomycin-treated mice had significantly higher pH in the jejunum, and germ-free mice had significantly higher pH in the jejunum, cecum, and proximal colon, underlining the role of gut microbes in regulating pH levels throughout the gastrointestinal tract. In conclusion, we show that mouse strain, vendor, and microbial presence, but not sex, influence gastrointestinal pH in mice. Given the importance of gastrointestinal pH for pharmacokinetics, drug delivery systems, and gastrointestinal microbial behavior, these data will provide an important foundation for the choice of mouse models for research involving the gastrointestinal tract.
Supplemental Oxygen Prevents Hypoxemia in Pigs (Sus domesticus) Chemically Restrained with Ketamine, Dexmedetomidine, and Diazepam.
Reis AN, Sanches MC, Henriques MA … +5 more , Pizzaia JN, Rusch E, Muro BBD, Garbossa CAP, Carregaro AB
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41412159 · Full text
The study described here evaluated the efficacy of supplemental oxygen in preventing hypoxemia (pO2 < 80 mm Hg) in pigs chemically restrained with ketamine, dexmedetomidine, and diazepam. Twenty gilts (154.5 ± 4.8 kg, 25...
The study described here evaluated the efficacy of supplemental oxygen in preventing hypoxemia (pO2 < 80 mm Hg) in pigs chemically restrained with ketamine, dexmedetomidine, and diazepam. Twenty gilts (154.5 ± 4.8 kg, 250 ± 2 days old) received a combination of ketamine (2 mg/kg), dexmedetomidine (10 µg/kg), and diazepam (0.1 mg/kg) via the auricular vein. Following induction, animals were positioned in right lateral recumbency and assigned to receive either ambient air (ambient air group, n = 10) or 100% oxygen at 5 L/min via a nasal cannula inserted 16 cm into one nostril (oxygen group, n = 10). Heart rate, peripheral oxygen saturation, and rectal temperature were monitored every 5 minutes. Arterial blood samples were collected at 5, 15, and 30 minutes to assess blood gas and electrolyte parameters. Induction time, time to sternal recumbency, time to standing, and recovery quality were also recorded. All gilts in the ambient air group developed hypoxemia, whereas those in the oxygen group maintained pO2 > 80 mm Hg. Peripheral oxygen saturation values were consistently higher in the oxygen group, whereas HR, respiratory rate, and temperature did not differ significantly between groups. Induction and recovery times, as well as recovery quality scores, were also similar between groups. Intranasal oxygen supplementation at 5 L/min effectively maintained arterial oxygenation and prevented hypoxemia in gilts anesthetized with the ketamine-dexmedetomidine-diazepam combination.
Pharmacokinetics of a Transdermal Buprenorphine Topical Solution in the Cynomolgus Macaque (Macaca fascicularis).
Santoro EL, Fortman JD, Messenger KM … +2 more , Enomoto H, Halliday LC
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41412155 · Full text
Pain management is an expansive and ever-evolving component of managing nonhuman primates in the research setting. Opioids are a commonly used analgesic medication and are available in a variety of formulations. A novel,...
Pain management is an expansive and ever-evolving component of managing nonhuman primates in the research setting. Opioids are a commonly used analgesic medication and are available in a variety of formulations. A novel, long-acting transdermal buprenorphine topical solution was recently approved for use in cats to provide up to 4 days of postoperative analgesia. The purpose of this study was to evaluate the pharmacokinetic profile of this transdermal formulation in cynomolgus macaques. Five male cynomolgus macaques were used in a 2-formulation crossover study to compare the pharmacokinetics of a single transdermal dose (20 mg) to a single intravenous dose of buprenorphine HCl (0.01 mg/kg). Plasma buprenorphine levels were measured for animals receiving transdermal buprenorphine topical solution at time points 0 (baseline), 1, 3, 6, 12, 24, 36, 48, 72, 96, and 120 hours postdosing. Plasma buprenorphine levels were measured for animals receiving intravenous buprenorphine at time points 0 (baseline), 2, 5, 10, 25, 45, and 60 minutes and at 3, 6, 12, and 24 hours postdosing. Animals weighing 3.55-6.2 kg reached therapeutic plasma levels, as hypothesized in the literature (0.1 ng/mL), within 1 hour of administration and maintained therapeutic levels for at least 72 hours. This study demonstrates that this novel transdermal buprenorphine topical solution can offer a refinement in pain management of nonhuman primates through a less invasive route of administration with an extended duration of action.
Refining the Guinea Pig (Cavia porcellus) Cryo-Injury Model for Cardiac Regeneration and Functional Characterization.
Nehring ME, von Bibra C, Geertz B … +8 more , Roessler G, Etzion Y, Castro L, Levi O, Burg S, Hiebl B, Eschenhagen T, Weinberger F
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41397434 · Full text
Guinea pigs have been a standard model in cardiovascular pharmacology and physiology research, but the advent of transgenic models has largely replaced them with mouse and rat models. However, guinea pigs remain importan...
Guinea pigs have been a standard model in cardiovascular pharmacology and physiology research, but the advent of transgenic models has largely replaced them with mouse and rat models. However, guinea pigs remain important models in cardiac electrophysiology, drug-induced arrhythmias, or atherosclerosis research, and they have recently gained importance for studying one specific research question, that is, transplantation of pluripotent stem cell derived cardiomyocytes to repair the cryo-injured heart. Their human-like cardiac electrophysiology, together with their small size that facilitates handling and housing, make guinea pigs a valuable experimental model for these studies. However, repeated open heart surgeries in guinea pigs are technically demanding and accompanied by high mortality. In this study, we retrospectively examined sequential protocol modifications and describe how protocol refinements led to improved survival rates. Cryo-injury was performed in female Dunkin-Hartley guinea pigs under general anesthesia with a liquid nitrogen-cooled probe via a lateral thoracotomy. Cells were transplanted during a second surgery 7 days later. We analyzed data from up to 558 animals to determine mortality rates and morphologic and functional parameters. Initial studies revealed a mortality rate of ∼50%. Sequential modifications led to a significant reduction, with the refined protocol achieving a perioperative mortality rate of ∼30%. The procedures were completed in <35 minutes, and survival rates for the observation period (up to 8 weeks) were 70%. Scar size was evaluated in 144 (4 weeks, n = 92; 8 weeks, n = 52) animals and showed a significant, but shallow correlation with echocardiographically determined heart function. Taken together, refined surgery protocols allow safe and reproducible cryo-injury with subsequent cell injections in guinea pigs with an improved mortality rate.
Why Is the Current Monitoring of Rodentibacter spp. Exclusively by Molecular Methods Insufficient?
Benga L, Benten WPM, Bischoff SJ … +1 more , Christensen H
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41381065 · Full text
The former [Pasteurella] pneumotropica complex has rendered until now 12 Rodentibacter species, which has implications in the monitoring of these highly prevalent laboratory rodent microorganisms. Rodentibacter spp. are...
The former [Pasteurella] pneumotropica complex has rendered until now 12 Rodentibacter species, which has implications in the monitoring of these highly prevalent laboratory rodent microorganisms. Rodentibacter spp. are known as classic opportunistic pathogens of laboratory rodents and represent noteworthy members of the oral and genital microbiome, with potential pathophysiological interferences in colonized animals. Laboratory mice and rats are predominantly colonized by host-specific Rodentibacter spp., with R. pneumotropicus and R. heylii as mouse-specific species and R. ratti, R. heidelbergensis, R. rarus, and R. trehalosifermentans as rat-specific species; however, host specificity of R. haemolyticus, currently prevalent in both species, remains to be elucidated. Nevertheless, cross contaminations with the taxa from the opposite host occurs between mice and rats. The monitoring occurs by classic culture and/or by molecular techniques, although the latter are currently available only for a few Rodentibacter taxa. Unfortunately, many current health monitoring strategies do not take into consideration the host specificities of these taxa and are often focused nearly exclusively on the molecular diagnostics of R. pneumotropicus and R. heylii, thus neglecting the remaining taxa. Until future research addresses the lack of molecular tests available for all relevant Rodentibacter spp. and a host-specific monitoring is implemented, we consider that monitoring exclusively by current molecular methods risks missing opportunistic members of this genus. Importing laboratory rodents based on health reports relying solely on molecular assays is currently associated with an increased risk of accepting Rodentibacter-positive animals.
The Use of Ampicillin-Medicated Diet to Treat Segmented Filamentous Bacteria in a Mouse (Mus musculus) Colony.
Schoenberger J, Bowers CJ, Langan GP … +1 more , Luchins KR
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41365337 · Full text
Segmented filamentous bacteria (SFB), or Candidatus savagella, are gram-positive, spore-forming, filamentous commensal bacteria that colonize the ilea of mice and rats. SFB can impact certain research studies due to thei...
Segmented filamentous bacteria (SFB), or Candidatus savagella, are gram-positive, spore-forming, filamentous commensal bacteria that colonize the ilea of mice and rats. SFB can impact certain research studies due to their effect on the innate and adaptive immune system. Therefore, there is a need to eliminate SFB from some rodent colonies. Antibiotics are an effective treatment method that have been shown to be successful at eradicating this bacterium. Commonly, antibiotics are supplied to rodents via water. However, antibiotics in water have several limitations, depending on the type of water and the length of time in water, and administration is labor intensive. Therefore, this study sought to create a rodent diet containing the antibiotic ampicillin. The feed was constructed to counter an expected ampicillin concentration decrease from the pelleting process and irradiation. Mice were placed on the ampicillin feed for 4 weeks, and SFB was measured via PCR fecal analysis. After one week of feeding the ampicillin diet, all mice in the treatment group were negative for SFB. These mice remained negative for 2 additional weeks after treatment cessation. This study shows ampicillin diet is an effective method to eliminate SFB from mouse colonies.
Longevity and Catheter-Related Infection Rates in Nonhuman Primates with Chronic Indwelling Intravenous Catheters.
Lewis E, Rough MI, Roberts BF … +3 more , Costa MB, Czoty PW, Nader MA
J Am Assoc Lab Anim Sci · 2025 Dec · PMID 41349960 · Full text
In preclinical models, indwelling intravenous catheters and vascular access ports are often essential components of biomedical research aimed at modeling human disease. For instance, animal models of drug self-administra...
In preclinical models, indwelling intravenous catheters and vascular access ports are often essential components of biomedical research aimed at modeling human disease. For instance, animal models of drug self-administration are used for many reasons, including to assess abuse liability, to study physiologic and neurologic consequences of drug exposure, and to examine the efficacy of behavioral and/or pharmacological interventions. The most frequent route of drug self-administration in preclinical animal models is the intravenous route via indwelling intravenous catheters. The present study examined 23 years of drug self-administration studies in Old World macaques used in drug self-administration studies at Wake Forest University School of Medicine. The medical records for individually or pair-housed adult rhesus monkeys (n = 10 females and 172 males) and socially housed cynomolgus monkeys (n = 64 females and 92 males), all implanted with indwelling intravenous catheters and associated vascular access ports, were examined. The most frequent vein catheterized was the femoral vein, followed by the internal and external jugular vein; the least frequent was the brachial vein. The infection rates over 23 years and >500 catheters in cynomolgus and rhesus monkeys were 13.7% and 10.3%, respectively. The average catheter remained patent and implanted in the vein for 22.5 months in cynomolgus monkeys and 15.5 months in rhesus monkeys. These findings highlight significant strengths in using Old World macaques, both rhesus and cynomolgus, in long-term, longitudinal studies involving indwelling intravenous catheters.
Social Housing of Male CD-1 Mice (Mus musculus) in the Toxicological Setting: A 28-Day Social Compatibility Study of Male Mice following Oral Gavage of Theophylline.
Blakie L, Alves S, Chase FT … +2 more , Aulgur AB, Kylie J
J Am Assoc Lab Anim Sci · 2025 Nov · PMID 41285377 · Full text
Group or pair housing of social animals in laboratory settings is beneficial to animal welfare. Social housing of male mice can be difficult due to possible aggressive behaviors, leading to injury and resulting in animal...
Group or pair housing of social animals in laboratory settings is beneficial to animal welfare. Social housing of male mice can be difficult due to possible aggressive behaviors, leading to injury and resulting in animals not being able to continue in the study. Techniques used to decrease male mouse aggression and territorial behaviors have been described in recent literature, including pairing mice before sexual maturity, moving used nesting material over during cage changes, removing high-value items that can encourage territorial behaviors, and using low-stress handling techniques. Using these suggested tactics, we conducted a 28-day study determining the social compatibility of male CD-1 mice in a standard toxicological study design. Forty-eight mice, aged 5 weeks old, were equally divided into single and pair housing and were administered theophylline daily. Animals were exposed to common toxicology study procedures known to cause additional stress including repeated blood collections, daily dosing, weekly clinical observations and body weights, and terminal urine collections. Behavioral assays, including nest scores and time-to-integrate-nest-material testing, were performed weekly, and pelt scores were collected postmortem. Fecal samples were collected intermittently for fecal corticosterone metabolite analyses. No mouse pairs required separation throughout the dosing phase of study, and no significant differences were observed that would affect toxicology studies. This suggests that by using techniques to decrease agonistic behaviors, male mice can be successfully socially housed on acute and subacute toxicology studies.
The Analgesic Effect of Two Different Extended-Release Meloxicam Formulations for Attenuation of Hypersensitivity in Rats (Rattus norvegicus).
Ge Y, Alamaw ED, Jampachaisri K … +3 more , Sharp P, Pacharinsak C, Huss MK
J Am Assoc Lab Anim Sci · 2025 Nov · PMID 41285370 · Full text
Meloxicam is a nonsteroidal anti-inflammatory drug (NSAID) frequently administered every 24 hours to control mild to moderate pain in rodents. Extended-release meloxicam offers a refinement of less frequent dosing and an...
Meloxicam is a nonsteroidal anti-inflammatory drug (NSAID) frequently administered every 24 hours to control mild to moderate pain in rodents. Extended-release meloxicam offers a refinement of less frequent dosing and an extended therapeutic window compared with the standard daily-dosed meloxicam formulation. The aim of this study was to compare the analgesic efficacy of 2 different extended-release meloxicam formulations to a standard meloxicam formulation in a rat incisional pain model. Adult Long-Evans rats (n = 33) were randomly assigned into one of 4 treatment groups (n = 8-9 per group): (1) saline (0.9% NaCl, 5 mL/kg, SC, once); (2) meloxicam (Melox; 2 mg/kg, SC, every 24 hours); (3) meloxicam extended-release polymer (Melox-ER; 4 mg/kg, SC, once); or (4) meloxicam extended-release suspension (Melox-XR; 4 mg/kg, SC, once). Under isoflurane anesthesia, a 1-cm longitudinal skin incision was made on the plantar hind paw 5 minutes after drug administration. Mechanical and thermal hypersensitivity assessments were performed one day before surgery (-24 hour), 4 hours after surgery (4 hour), and 3 consecutive days following surgery (24, 48, and 72 hours). Mechanical (4-48 hours) and thermal (4-72 hours) hypersensitivity were observed in the saline group. Melox-ER did not attenuate mechanical or thermal hypersensitivity at any time point. Melox and Melox-XR attenuated mechanical hypersensitivity at the 48-hour time point. No abnormal clinical signs were noted, but injection site reactions were noted in the Melox, Melox-ER, and Melox-XR groups. Further research is needed to evaluate rat meloxicam analgesic dosages for incisional pain.
Developmental Potential of In Vitro Fertilization-Derived Mouse Zygotes Following Vitrification: Effects of Superovulation Method.
Gerb SA, Agca C, Agca Y
J Am Assoc Lab Anim Sci · 2025 Aug · PMID 41270942 · Full text
Cryopreservation of pronuclear stage embryos from superovulated mice is beneficial to safeguard genetically modified (GM) mouse strains as well as the efficient production of novel GM mouse strains. C57BL/6J female mice...
Cryopreservation of pronuclear stage embryos from superovulated mice is beneficial to safeguard genetically modified (GM) mouse strains as well as the efficient production of novel GM mouse strains. C57BL/6J female mice were superovulated with either anti-inhibin serum (AIS) or equine chorionic gonadotropin (eCG), and the resulting oocytes were inseminated via in vitro fertilization (IVF) to produce pronuclear stage embryos. A subset of fresh embryos was cultured in vitro to assess their developmental potential to the blastocyst stage, and the remaining embryos derived from either AIS or eCG superovulation methods were cryopreserved via vitrification and subsequently assessed to determine both in vitro and in vivo developmental competence. The percentage of IVF-derived fresh embryos that developed to 2-cell (92.9 ± 4.1 compared with 92.4 ± 4.2) and the blastocyst stage (91.9 ± 3.84 compared with 91.8 ± 7.9) from eCG and AIS, respectively, was not different (P = 0.89). The percentage of the vitrified pronuclear embryos that were intact after warming for eCG (93.08 ± 5.96) and AIS (88.0 ± 6.63) mice was different (P = 0.039). However, the percentage of IVF-derived vitrified warmed zygotes that developed to 2-cell (82.23 ± 7.18 compared with 83.9 ± 7.22) and the blastocyst stage (71.35 ± 7.76 compared with 74.52 ± 5.57) from eCG and AIS, respectively, was not different. Vitrified pronuclear embryos produced after either AIS or eCG-administered mice were in vitro cultured to 2-cell and surgically transferred into CD-1 surrogate mothers to compare pregnancy rates and live birth rates. There were no differences in percent pregnancy rates between eCG (85.7) and AIS (85.7) superovulation methods. Similarly, there were no differences in the percentage of live offspring between eCG (27.6) and AIS (23.2) superovulation methods. This study suggests that eCG and AIS superovulation methods yield similar in vitro and in vivo embryonic development rates following vitrification, and thus, AIS may be preferred, especially for the strains with difficulty in obtaining large quantities of oocytes or embryos for the production of GM mice or genome banking.
About
- Frequency
- Sun
- Papers found
- 200
- RSS feed
- Subscribe