Journal Of The American Association For Laboratory Animal Science[JOURNAL]
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200 papers
Best Practices for Supporting Professional Identity Formation during Laboratory Animal Medicine Residency Training.
Nowland MH, Haidet P, Stuckey H … +1 more , Whitcomb TL
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683646 · Full text
Professional identity formation (PIF) is the dynamic psychosocial process crucial to becoming enculturated into a profession. This nonlinear process starts with entrance into a training program and ideally results in the...
Professional identity formation (PIF) is the dynamic psychosocial process crucial to becoming enculturated into a profession. This nonlinear process starts with entrance into a training program and ideally results in the harmonization of norms, values, and aspirations of the person with those of the chosen field. PIF is most successful when trainees can reflect, have positive role models and mentors, and receive social validation. Those who experience lack of support or hardship during PIF are at risk of burnout and poor mental health during their careers. Medical education research indicates that residency training significantly impacts PIF. This occurs because residents' new patient care responsibilities force them to grapple with the differences between the ideal practice taught in medical school and the realities of their work lives. Emerging evidence in veterinary medical education research indicates that residents enrolled in laboratory animal medicine (LAM) residency programs experience similar tensions as they navigate relationships with stakeholders, encounter conditional valuation of their veterinary knowledge, and feel powerless to enact changes. To explore best practices for supporting PIF for developing LAM veterinarians, we performed a qualitative analysis of written comments from surveys completed by attendees at the 2022 American College of Laboratory Animal Medicine Forum meeting. Results were organized by 5 themes: (1) empowering residents to step into their authority and understand the limitations of their roles, (2) providing support for learning about the complexities of relationships within LAM, (3) serving as role models and mentors in building relationships, (4) creating opportunities to learn professional communication, and (5) advocating for the specialized and explicit value of the profession (LAM). From these results, we constructed a model that illustrates the PIF process for LAM veterinarians in training, with the goal of raising awareness of the connection between the quality of PIF and career wellness.
Effect of Mouse (Mus musculus) Sex and C57BL/6 Substrain on Sensitivity to Isoflurane and Ketamine-Xylazine-Acepromazine Anesthesia.
Tuohy KP, Tynan AR, Gerisma JN … +1 more , Marx JO
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683645 · Full text
Anesthesia is commonly performed with mice in the research setting. Standard doses of anesthetic drugs are typically recommended, without customization to strain, substrain, or sex. The purpose of this study was to evalu...
Anesthesia is commonly performed with mice in the research setting. Standard doses of anesthetic drugs are typically recommended, without customization to strain, substrain, or sex. The purpose of this study was to evaluate C57BL/6 substrain and sex differences in response to isoflurane and ketamine/xylazine/acepromazine (KXA) injectable anesthesia. Female and male C57BL/6NTac, C57BL/6J, C57BL6/6NHsd, and C57BL/6NCrl mice were sourced from 4 different vendors. Isoflurane anesthesia trials were performed with a subset of the mice (n = 24) to determine the minimum alveolar concentration (MAC). Loss of righting reflex, total loss of righting time, time to loss of pedal withdrawal reflex, and total time at surgical plane were evaluated for mice (n = 64) administered 100 mg/kg ketamine, 10 mg/kg xylazine, and 1 mg/kg acepromazine by intraperitoneal injection. Heart rate, respiratory rate, and hemoglobin oxygen saturation (SpO2) were monitored throughout each anesthetic event. Isoflurane MAC was not affected by sex or substrain. In the KXA trials, male mice exhibited a longer duration of loss of righting reflex and remained at a surgical plane of anesthesia significantly longer than the female mice. No significant differences in substrain were detected in the depth or duration of anesthesia. Evaluation of physiologic parameters revealed differences in heart rate between substrains, with C57BL/6NHsd mice exhibiting significantly lower heart rates than the other 3 substrains during both isoflurane and KXA anesthesia. C57BL/6J mice had the highest heart rates during KXA anesthesia. These heart rate differences can impact clinical monitoring practices and are important to consider when selecting strains for study models, especially for cardiovascular studies. In conclusion, the male C57BL/6 mice exhibited a longer duration of anesthesia in response to KXA, while no substrain differences were detected for anesthetic depth or duration of either isoflurane or KXA anesthesia.
Isolation, Characterization, and Epizootiology of Clostridioides cuniculi from Immunodeficient Mice with Enteric Disease.
Funk A, Crawford A, Nickerson K … +10 more , Janke L, Stringer T, Sun Y, Marsh A, Inoue M, Savage C, Emmons J, Henderson K, Tang L, Pisharath H
J Am Assoc Lab Anim Sci · 2025 May · PMID 40683644 · Full text
Mouse strains deficient in adaptive and innate immune functions, such as NSG, NSG-SGM3, and NBSGW, are highly susceptible to opportunistic infections. Over a period of 7 mo, 1,193 mice from the above 3 strains in an SPF...
Mouse strains deficient in adaptive and innate immune functions, such as NSG, NSG-SGM3, and NBSGW, are highly susceptible to opportunistic infections. Over a period of 7 mo, 1,193 mice from the above 3 strains in an SPF barrier were observed with mild loose stool (LS). Affected mice had minimal weight loss and mortality. Histopathology revealed erosion of the jejunal villi with neutrophilic inflammation and Gram-positive bacterial rods adhering to the cecal mucosa with varying degrees of mucosal hyperplasia, epithelial vacuolation, and apoptosis. Anaerobic culture revealed a clostridial species that could not be speciated using standard biochemical phenotyping. Further, Clostridioides difficle and Clostridioides perfringens ELISA on intestinal contents were negative for toxins. We performed a challenge study by exposing naïve NSG mice to dirty bedding from affected cages; metagenomics on pre- and postchallenge feces identified and associated the etiopathogenesis to Clostridioides cuniculi. Whole genome sequencing and phylogenetic analysis confirmed the identity of C. cuniculi. The isolate was sensitive to trimethoprim-sulfamethoxazole (TMS). TMS was effective in abrogating signs of LS and clearing infection in mice in studies. A probe-based real-time PCR specific for C. cuniculi was established. This assay was used to screen environmental and fomite contamination and potential use in rack-level screening. We traced the source of the outbreak to a NBSGW breeding colony. However, in our observation, spontaneous C. cuniculi-induced disease was only seen in the presence of an irradiated diet in the breeding NBSGW strain and not in the breeding colonies of NSG or NSG-SGM3 strains. Interestingly, we observed that exposure to infected feces from NBSGW-induced LS in both NSG and NSG-SGM3 mice. This investigation provides insights into the etiopathogenesis and probable source of sporadic clostridial infections in immunodeficient mice and lays the groundwork for its prevention and surveillance in immunodeficient mouse colonies.
Influence of Water Delivery Method on the Gut Microbiome in Laboratory Mice (Mus musculus).
Kravitz A, Lawton S, Buckmaster CA … +3 more , Little TF, Lohse D, Hankenson FC
J Am Assoc Lab Anim Sci · 2025 May · PMID 40683643 · Full text
Nuances related to the milieu of the gastrointestinal tract have led to investigations of environmental (or extrinsic) factors, like feed sources and fluid intake, and their influences on the gut microbiome in research a...
Nuances related to the milieu of the gastrointestinal tract have led to investigations of environmental (or extrinsic) factors, like feed sources and fluid intake, and their influences on the gut microbiome in research animals. Water is typically provided to laboratory mice either by reusable water bottle (RWB), housing rack automatic water (RAW) delivery, or single-use disposable plastic pouch (DPP). In this study, the influence of differing water delivery methods on gut microbiome stability was evaluated in immunocompetent (n = 36 B6; 18 male [M]:18 female [F]) and immunocompromised (n = 36 NOG; 18 M:18 F) strains of mice. Mice were housed on a single IVC rack in sex-specific groups and provided with autoclaved caging and bedding, irradiated feed, and chlorinated, reverse-osmosis water provided by one of 3 delivery methods (8 cages per method). Access to the room was restricted to select personnel to conduct animal care and sample collection tasks. Fecal pellets (n = 2) were collected from each animal every other week, and water samples were collected weekly for analysis. Over the course of the study, bacteria were detected in 11% of the RWB samples (7 of 63) and 4% of the RAW samples (1 of 25). DPP samples were consistently free of bacterial contamination. Shotgun metagenomics and statistical analyses revealed overt shifts in gut microbiota in the majority of mice throughout the study (21 of 25 cages). Histologic examinations of organs from representative clinically normal study mice (n = 12) were unremarkable. With minimal exceptions, microbiome shifts were statistically significant across cage cohorts, despite attempts to control experimental variables. This study is the first to demonstrate that the water delivery method does not impart a significant influence on gut microbiota stability in research rodents and highlights the need to document water type, treatment, and delivery method as extrinsic factors in reporting animal studies.
Calcinosis Circumscripta with Iron Mineralization in an African Green Monkey (Chlorocebus aethiops sabaeus).
Feng J, Paraschou G, Beierschmitt A … +2 more , Kemper RT, Bolfa P
J Am Assoc Lab Anim Sci · 2025 May · PMID 40683636 · Full text
A 19-y-old, colony-born, female African green monkey (Chlorocebus sabaeus) presented for recurrent swelling measuring 11 × 5 × 4 cm on the right thigh, around the stifle, which started 5 y previous, resulting in lameness...
A 19-y-old, colony-born, female African green monkey (Chlorocebus sabaeus) presented for recurrent swelling measuring 11 × 5 × 4 cm on the right thigh, around the stifle, which started 5 y previous, resulting in lameness. The affected area had alopecia and crusting and felt lobulated on palpation. Radiographic evaluation revealed multiple foci of well-circumscribed, soft-tissue mineralization within the subcutis and underlying muscles. The monkey was euthanized due to poor quality of life. Postmortem exam demonstrated a yellow-to-red, friable, crepitant, nonencapsulated multilobulated mass, infiltrating skeletal muscles of the right thigh and containing multiple white hard spicules. Microscopic examination revealed abundant irregular-to-globoid amphophilic material (mineralization) in the subcutis and skeletal muscle. The mineralization was surrounded by extensive fibrous connective tissue (fibrosis), lymphocytes, macrophages, and multinucleated giant cells. Histochemical staining, scanning electron microscopy, and infrared spectroscopy determined the mineral material to be composed of calcium phosphate and small amounts of collocated iron. The findings were most consistent with a diagnosis of calcinosis circumscripta (sometimes referred to as tumoral calcinosis). Calcinosis circumscripta in African green monkeys has not previously been reported, although this condition has been reported in rhesus macaques, a common marmoset, and a cynomolgus macaque. The cause of iron mineralization in this case was unknown, and its occurrence within calcinosis lesions has not been previously documented.
A Novel 3D-Printed Mouse Model for Surgical Training: Multicenter Construct, Face, and Content Validation Study.
Celdran-Bonafonte D, Gantenbein F, Ruiz Perez D … +2 more , Rumpel R, Eva Trimmel N
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683634 · Full text
Advancements in laboratory animal training increasingly incorporate technological innovations aiming to better align training standards with the 3Rs (Replacement, Reduction, and Refinement). This trend is shifting away f...
Advancements in laboratory animal training increasingly incorporate technological innovations aiming to better align training standards with the 3Rs (Replacement, Reduction, and Refinement). This trend is shifting away from traditional reliance on live animals and cadavers toward simulation-based methods. This study introduces and assesses the validity of a novel 3D-printed rodent surgical simulator designed for the practice and training of basic rodent surgical skills. To evaluate its potential to partially replace animal use, refine rodent surgical training, and reduce the number of animals needed, a multicenter validation study across 5 European and US research academic centers was conducted. The study assessed the simulator's face, content, and construct validity, involving participants inexperienced and experts in rodent surgery. The construct validity was evaluated through task completion times and blinded quality assessments across multiple training iterations. The results revealed that inexperienced participants demonstrated significant improvements in both speed and quality of surgical tasks with repeated simulator use, eventually reaching performance levels comparable to experts' initial attempts. Expert participants consistently outperformed the inexperienced group. Face and content validity were supported by postuse surveys, with high ratings from both groups regarding the simulator's anatomic realism and its perceived usefulness for the acquisition and development of fundamental surgical skills. Overall, the findings of this study support that this 3D-printed rodent surgical simulator offers a realistic, effective, and ethically sound alternative for basic rodent surgical skills training and competency assessment.
Dietary Fenbendazole Treatment Does Not Impair Skilled Forelimb Motor Function in C57BL/6J Mice.
Fracassi M, Rodrigues da Silva T, Wilding LA … +1 more , Jones TA
J Am Assoc Lab Anim Sci · 2025 May · PMID 40683633 · Full text
Fenbendazole (FBZ) treatment for pinworm infections is generally safe and effective but not without concern for potential research complications in its application to laboratory animal colonies. Previously, dietary FBZ w...
Fenbendazole (FBZ) treatment for pinworm infections is generally safe and effective but not without concern for potential research complications in its application to laboratory animal colonies. Previously, dietary FBZ was found to impair motor performance in C57BL/6N mice, an effect that endured at least 2 wk posttreatment. These findings raised the possibility that FBZ treatment would complicate our own research on poststroke motor function in C57BL/6J mice. Here we present the results of a study that tested this possibility in the context of facility-wide FBZ treatment based on repeated measures in a skilled reaching task that is extremely sensitive to forelimb motor impairments. Mice of both sexes that were proficient in the reaching task were measured in their performance of the task in each of the 4 wk preceding, 7 wk during, and 2 wk after dietary FBZ treatment that alternated weekly between therapeutic and subtherapeutic doses. There was no indication of a notable decrement or other change in reaching performance during or after FBZ treatment (mean ± SE percent success before, during, and after treatment = 57 ± 2, 53 ± 2, and 60 ± 2; n = 20). Performance stability in FBZ-treated mice was similar to that of untreated mice. These results are significant for revealing a lack of noticeable influence of FBZ on a commonly used measure of motor function in a widely used mouse strain. The difference in FBZ effects relative to the prior study could reflect substrain-dependency (6N compared with 6J) and/or differences in motor behavioral measures.
Repeated Administration of Pharmaceutical-Grade Medium-Chain Triglycerides, a Common Pharmacologic Excipient, Confers Dose-Dependent Toxicity by the Intraperitoneal but Not Oral Route in Mice.
Adler-Wachter M, Tsai JY, Schweitzer BN … +4 more , McDonough A, Barker-Haliski M, Snyder JM, Weinstein JR
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683632 · Full text
Pharmaceutical-grade medium-chain triglycerides (MCTs) are common excipients for in vivo pharmacological studies in laboratory animals and as an experimental therapeutic in certain metabolic and neurologic disorders. In...
Pharmaceutical-grade medium-chain triglycerides (MCTs) are common excipients for in vivo pharmacological studies in laboratory animals and as an experimental therapeutic in certain metabolic and neurologic disorders. In this study, we examined the tolerability of repeated administration of a pharmaceutical-grade formulation of 3 MCTs-caprylic, capric, and lauric acid-in mice via the oral and intraperitoneal routes. We administered either 8 or 4 µL of 100% MCTs or saline/gram of body weight (∼7.56 or 3.78 g/kg, respectively) twice daily for 7 d. During administration, and for 7 d after, we monitored weight change and clinical presentation. On day 14, or upon meeting euthanasia criteria, animals were sacrificed for gross necropsy, histology, and CBC. We observed significant weight loss, clinical decline, and 100% mortality in animals receiving 8 µL/g MCTs via the intraperitoneal route of administration. Gross necropsy revealed serosanguinous fluid in the thoracic cavity, dark red mottled lungs, and adhesions in the abdominal cavity. Histology confirmed inflammation of the lungs, mediastinum, and peritoneum. Mild pathology and initial weight loss (through day 3) were also present in mice receiving 4 µL/g MCTs IP. However, these animals regained weight by day 7 and exhibited no clinical decline or mortality. These adverse effects were not seen in animals receiving either 8 µL/g MCTs PO or 8 µL/g saline IP. These findings suggest that repeated intraperitoneal administration of MCTs may cause dose-dependent toxicity and mortality at high doses, but it confers no adverse effects when administered via the oral route.
Evaluation of Sentinel-Free Soiled Bedding as a Replacement for Direct Sampling in PCR Detection of Rodent Pathogens during Quarantine.
Feinberg A, Nickerson KP, Woods CL … +4 more , Reimer D, Henderson KS, Andersen RP, Singh B
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683631 · Full text
Establishing a screening method for rodent pathogens is an integral component of an institution's rodent health surveillance program. Most rodent quarantine programs use direct colony sampling (DCS) from live animals for...
Establishing a screening method for rodent pathogens is an integral component of an institution's rodent health surveillance program. Most rodent quarantine programs use direct colony sampling (DCS) from live animals for pathogen PCR testing. DCS may elicit undue stress to the animal and be time consuming, contingent on the number of quarantined animals. Sentinel-free soiled bedding (SFSB) sampling has previously been used to monitor the pathogen status of research rodents. A pilot study was conducted to determine the feasibility of an SFSB-based quarantine by comparing it to DCS for the evaluation of pet shop mice of different age ranges. Enhanced detection by SFSB for the 6- to 10-wk age range supported further investigation. The subsequent main study evaluated whether SFSB sampling is as effective as traditional DCS for detecting rodent pathogens. We hypothesized that SFSB contact media sampling is either equivalent to or more effective than DCS for detecting pathogens in quarantined mice. The study included mice imported from various institutions between October 2023 and August 2024. The DCS and exposed contact media were tested using PCR analyses. The total number of positive agent assay detections by DCS was 157, compared with 173 with the SFSB method. These results suggest that contact media sampling provides equivalent or superior detection of rodent pathogens compared with the DCS method. Although not statistically significant, it was observed that delaying sample submission decreased detection rates for 2 RNA viruses: 80% for murine astrovirus-1 (MuAstV1; 4 out of 5 samples) and 67% for genogroup V norovirus (MNV; 4 out of 6 samples). Immediate submission restored the detection rate to 100% for MuAstV1 and 91% for MNV. To conclude, SFSB rapid submission during quarantine provides a reliable and effective alternative to the traditional DCS method for the detection of rodent pathogens. This nonintrusive methodology mitigates stress during sampling while enhancing the effectiveness and sensitivity of pathogen detection.
Evaluation of 415-nm Blue Light and Hypochlorous Acid on the Rhesus Macaque (Macaca mulatta) Cranial Implant Microbiota.
Lieberman MT
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683630 · Full text
Cranially-implanted macaques are a crucial model for neuroscience research. Implant complications include abscesses, meningoencephalitis, and implant-tissue margin infections. Antimicrobial overuse has increased bacteria...
Cranially-implanted macaques are a crucial model for neuroscience research. Implant complications include abscesses, meningoencephalitis, and implant-tissue margin infections. Antimicrobial overuse has increased bacterial resistance, risking macaque health and complicating treatment of infections. This project aimed to assess the antimicrobial effects of blue light (∼415 nm) and hypochlorous acid (HOCl) treatment of cranial implant margins. Blue light exerts antibacterial effects via the induction of reactive oxygen species. We hypothesized that exposing cranial implant margins to a commercially available blue light device followed by HOCl treatment would improve clinical appearance and decrease bacterial burden as assessed by aerobic/anaerobic culture and tissue margin microbiota analysis (decreased α and β diversity and altered taxonomic composition). Eight rhesus macaques were exposed to 6 min of blue light followed by 0.024% HOCl solution three times weekly for 4 wk. Swabs for microbiota analysis and bacterial cultures were collected before and 24 h after the last treatment session. Control microbiota swabs were collected from a separate implant margin area only exposed to HOCl. All animals tolerated the blue light exposure but had varied improvement in margin clinical appearance. The most common bacteria identified on culture were Staphylococcus aureus (n = 8), β-hemolytic streptococcus (n = 8), and Corynebacterium ulcerans (n = 6). Microbiota analysis of the 16S rRNA V4 gene region demonstrated many anaerobic operational taxonomic units in addition to the aerobic species cultured, highlighting limitations of culture-based methods. All animals had unique microbiota taxonomic profiles with a mean of 84 operational taxonomic units and a median Shannon diversity index of ∼2.6. No significant differences were found between treatment groups, α diversity, or β diversity before and after the study. The effectiveness of blue light therapy likely relates to the device power and depth of penetration into the tissue margin. While safe, future work is needed to optimize the dose and delivery methods of light-based therapies.
Comparison of Intrarenal and Intravenous Injections of Sodium Pentobarbital for Euthanasia in New Zealand White Rabbits (Oryctolagus cuniculus).
LeGrand JL, Ozawa SM, Silverstein-Metzler MG … +5 more , Estes JM, Moiseiwitsch NA, Stephens JQ, Atkins HM, Petritz OA
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683629 · Full text
Peripheral venous access in rabbits can be difficult to obtain. When failure occurs, there is a dire need for alternative vascular access routes to be available. The AVMA categorizes intrarenal injection of pentobarbital...
Peripheral venous access in rabbits can be difficult to obtain. When failure occurs, there is a dire need for alternative vascular access routes to be available. The AVMA categorizes intrarenal injection of pentobarbital as acceptable with conditions for euthanasia. Animals must be in an unconscious state, and only minimal studies using intrarenal administration have been reported. A total of 53 rabbits were used to conduct 3 separate analyses to assess and measure the efficacy, efficiency, and validity of the intrarenal route for euthanasia in New Zealand White rabbits by assessing the time to cardiopulmonary arrest (TCPA). Animals were sedated with 40 mg/kg ketamine and 50 μg/kg dexmedetomidine intramuscularly into the lumbar muscles, and timing started at the beginning of the injection and ended when cardiac and respiratory arrest were observed. Cardiac and respiratory arrest following intravenous injection of pentobarbital was significantly quicker (cardiac, 6 to 24 s, median 9 s; respiratory, 6 to 19 s, median 9 s; P < 0.001) than for the intrarenal route (cardiac, 40 to 900 s, median 411 s; respiratory, 23 to 900 s, median 120 s; P < 0.001), with no negative animal reactions observed during euthanasia injection performance. Four animals did not achieve TCPA within 15 min after administration. Although TCPA was longer with intrarenal compared with intravenous euthanasia (P < 0.001), this study demonstrates that the intrarenal approach under anesthesia is a feasible alternative to the intravenous approach, as it can be reliably performed without observed animal distress or alterations in organ pathology. The overall information from this study can help guide both laboratory and practicing clinicians considering this technique. Still, factors such as variable times to cardiopulmonary arrest and technical skill should be considered.
Comparison of Dexmedetomidine/Morphine and Xylazine/Morphine as Premedication in Isoflurane-Anesthetized Sheep.
Akaraphutiporn E, Bunnag P, Limprasutr V … +6 more , Rattanapinyopituk K, Durongphongtorn S, Pablo LS, Sharp P, Pacharinsak C, Wangdee C
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683628 · Full text
In this study we investigated the sedative, anesthetic, and pulmonary histopathologic effects of dexmedetomidine/morphine (DM) and xylazine/morphine (XM) in sheep. We hypothesized that DM would provide profound sedation...
In this study we investigated the sedative, anesthetic, and pulmonary histopathologic effects of dexmedetomidine/morphine (DM) and xylazine/morphine (XM) in sheep. We hypothesized that DM would provide profound sedation and better maintain physiologic parameters under anesthesia than XM in sheep undergoing laparoscopic surgery. Nineteen male sheep were premedicated with either DM (dexmedetomidine [0.006 mg/kg] and morphine [0.3 mg/kg]) or XM (xylazine [0.1 mg/kg] and morphine [0.3 mg/kg]). After DM or XM administration, 3 blinded veterinarians evaluated sedation scores (0 [no sedation], 1 [mild], 2 [moderate], 3 [severe]). Sheep were induced with intravenous tiletamine/zolazepam, intubated, and maintained with isoflurane in 100% oxygen. Anesthetic parameters were monitored for 60 min, including heart rate, respiratory rate, indirect blood pressure, oxygen saturation, end-tidal carbon dioxide, body temperature, arterial blood gas analysis, and isoflurane requirement. At the end of the procedure, the sheep were euthanized, and lung pathology (pulmonary edema) was assessed. The results showed that the sedation scores did not differ between DM (0.8 [0.4 to 1.0]) and XM (1.0 [1.0 to 1.0]). In addition, the anesthetic parameters were comparable between the groups, but the DM group exhibited a higher heart rate than the XM group. Finally, marked pulmonary changes, consistent with pulmonary edema, were observed in the XM group. In conclusion, DM and XM provided similar sedation and physiologic stability under isoflurane anesthesia, but DM may help minimize bradycardia and was associated with less evidence of pulmonary edema.
Optimization of Ketamine/Xylazine Anesthesia in Geriatric Mice.
Beecy S, Meuse D, Kizielewicz N … +2 more , Beale C, Molk D
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683626 · Full text
Aged mice are becoming increasingly important models for human senescence. Many studies require anesthesia. Standard rodent ketamine/xylazine injectable regimens have been associated with increased incidences of death, u...
Aged mice are becoming increasingly important models for human senescence. Many studies require anesthesia. Standard rodent ketamine/xylazine injectable regimens have been associated with increased incidences of death, unreliable surgical planes, and prolonged recoveries in geriatric mice. We hypothesized that the addition of atipamezole reversal and higher doses of ketamine or xylazine would result in a more reliable surgical plane of anesthesia and quicker recovery in geriatric mice without increasing mortality. Mice (n = 6 per group) were subjected to one of 3 anesthetic regimens: 100 mg/kg ketamine and 10 mg/kg xylazine without reversal (Standard); 150 mg/kg ketamine and 10 mg/kg xylazine with 1 mg/kg atipamezole reversal (High Ketamine); or 100 mg/kg ketamine and 15 mg/kg xylazine with 1 mg/kg atipamezole reversal (High Xylazine). While anesthetized, righting reflex, pedal withdrawal reflex, heart rate, respiratory rate, arterial oxygen saturation (SpO2), and temperature were recorded. While both experimental groups provided a more consistent surgical plane of anesthesia, the High Ketamine group had both the longest anesthetic period and the highest mortality (33.3%). The High Xylazine group had moderate mortality (16.6%) and a comparable anesthetic period to the Standard regimen, along with a superior SpO2 to both groups. Atipamezole reversal led to a faster return of righting reflex and an increase in SpO2 but did not affect the total length of recovery compared with the Standard group that did not include a reversal agent. Overall, the High Xylazine group provided a more reliable surgical plane to the Standard group in geriatric mice but increased mortality (16.6%), and the addition of atipamezole as a reversal agent did not significantly change the length of recovery. The information gained from this study can help guide decisions regarding the use of ketamine and xylazine in geriatric mice for surgical procedures or lengthy procedures for which redosing might be necessary.
Identification and Treatment of a Storage Mite Infestation in Rats (Rattus norvegicus).
Lazo J, Hanson WH
J Am Assoc Lab Anim Sci · 2025 May · PMID 40683625 · Full text
Storage mites are environmental pests that commonly invade hay, grain, or stored food. While generally regarded as harmless, they have been reported to elicit allergic reactions in both humans and animals. Although stora...
Storage mites are environmental pests that commonly invade hay, grain, or stored food. While generally regarded as harmless, they have been reported to elicit allergic reactions in both humans and animals. Although storage mites are considered environmental contaminants, this case report describes an infestation of storage mites on rats (Rattus norvegicus) in a laboratory animal facility. Despite traditional diagnostic methods initially revealing negative results, mites were consistently observed under repeated direct microscopic examinations of the animals. Eventual positive pelage tapes confirmed the presence of the ectoparasites and identified them as mold or cheese mites (Tyrophagus brevicrinatus or Tyrophagus putrescentiae) via Sanger sequencing. To our knowledge, this report is the first to implement permethrin-soaked cotton balls for the successful treatment of mold mites in an entire rat colony. Furthermore, considering the initial negative diagnostic results, this report emphasizes the pelage tape method as highly susceptible to false negatives.
Baseline Characterization of Swine Leukocyte Antigen Diversity in GFP-Expressing Domestic Swine.
Furrukh A, Javed H, Whitworth K … +4 more , Steen L, Ho CS, Ayyad MF, Rajab TK
J Am Assoc Lab Anim Sci · 2025 Jun · PMID 40683624 · Full text
Yorkshire piglets serve as valuable animal models in biomedical research, including partial heart transplantation research. This study characterizes the swine leukocyte antigen (SLA) diversity within a cohort of 16 Yorks...
Yorkshire piglets serve as valuable animal models in biomedical research, including partial heart transplantation research. This study characterizes the swine leukocyte antigen (SLA) diversity within a cohort of 16 Yorkshire piglets, including 5 genetically modified to express green fluorescent protein (GFP). Employing SLA typing, we identified 25 unique SLA class I alleles (9 SLA-1, 11 SLA-2, 5 SLA-3) and 17 unique SLA class II alleles (8 DRB1, 6 DQB1, 3 DQA). Notably, an allele of SLA-1*08:XX was detected in 75% of the piglets, while haplotypes Lr-7.26 and Lr-6.12b were most frequent, occurring at 18.75%. Comparative analysis with previous studies revealed consistent genetic trends, although differences in haplotype frequencies underscore the influence of breeding practices and sample size on SLA allele and haplotype distribution. Our findings highlight the significant polymorphism in the SLA complex of Yorkshire piglets, which is relevant for their utility as preclinical models for studying transplantation outcomes. The characterization of GFP piglets provides crucial genomic data for future research in cell tracking and graft integration. While the study's relatively small cohort may limit its generalizability, it represents the first baseline SLA typing of GFP Yorkshire piglets, offering foundational insights into their genetic diversity. This work emphasizes the importance of standardized genetic mapping to enhance the reproducibility and utility of laboratory swine in biomedical research.
Double-Chambered Right Ventricle and Intraventricular Thrombosis Mimicking Double-Chambered Right Ventricle in Cynomolgus Monkeys (Macaca fascicularis).
Yoneda I, Nakayama S, Sankai T … +4 more , Ito-Fujishiro Y, Yasutomi Y, Koie H, Ageyama N
J Am Assoc Lab Anim Sci · 2025 Jul · PMID 40675602 · Full text
Reports of congenital heart disease in nonhuman primates are rare, and double-chambered right ventricle (DCRV), which is a rare congenital heart disease, in which an abnormal muscle bundle divides the right ventricle int...
Reports of congenital heart disease in nonhuman primates are rare, and double-chambered right ventricle (DCRV), which is a rare congenital heart disease, in which an abnormal muscle bundle divides the right ventricle into 2 chambers (a proximal high-pressure chamber and a distal low-pressure chamber), has not been previously reported. We diagnosed DCRV antemortem in 2 monkeys bred at The Tsukuba Primate Research Center that presented with cardiac murmurs. Subsequent diagnostic evaluation confirmed DCRV in one case, with the other diagnosed with midventricular obstruction having a pathophysiology similar to DCRV. The monkey that had DCRV exhibited a pathophysiology similar to that in humans with DCRV, while the other monkey had a condition mimicking DCRV which was due to a thrombus. We believe this to be the first report of DCRV and a rare DCRV-like pathophysiology due to a thrombus in the ventricle in nonhuman primates.
More Power for Less Money: Statistical, Power, and Cost Analyses That Account for Intracluster Correlation in Experiments with Same-Group Cage Mates.
Landes RD
J Am Assoc Lab Anim Sci · 2025 Jul · PMID 40675600 · Full text
In experiments with cohoused animals, outcome variables can become correlated among cage mates. This is called intracluster correlation. When cage mates are all of the same group, the experiment is similar to a cluster r...
In experiments with cohoused animals, outcome variables can become correlated among cage mates. This is called intracluster correlation. When cage mates are all of the same group, the experiment is similar to a cluster randomized trial in human studies. Intracluster correlation in same-group cage mate experiments is a type of pseudoreplication, and ignoring it in statistical analyses increases false-positive results. Herein, we provide a tutorial on how to account for intracluster correlation in statistical analyses. Specifically, this is done by including cage identifiers as an independent variable in a linear mixed model, a type of ANOVA. Because power analyses must be based on the planned statistical analyses, we also include effect size calculations and sample size calculations (types of power analyses) in the tutorial. Effect size and sample size calculations help assure regulatory committees, such as IACUCs, granting agencies, and journals, that experiments are properly powered. These calculations will show that designing experiments to have more cages and fewer animals per cage is more efficient than fewer cages with more animals per cage. This statistical efficiency, which means more power, can be translated into reduced animal numbers, one of the 3Rs (replace, reduce, refine) of animal research. We then perform cost analyses and show how the costs of more cages with fewer animals overall are often less expensive than the costs of fewer cages with more animals overall. Altogether, accounting for intracluster correlation in the experiment design and analysis of same-group cage mate experiments results in fewer statistical errors, reduced costs, and fewer animals. Finally, analyses are demonstrated using JASP, a free, open-source, user-friendly statistical software, and provide R and SAS code to perform the analyses.
Effect of Anesthesia on Hematologic Parameters of Female Domestic Swine (Sus scrofa domestica).
Carlson MM, Sciurba JD, Saunders KE … +1 more , Kopanke JH
J Am Assoc Lab Anim Sci · 2025 Jul · PMID 40675597 · Full text
Swine are commonly used in biomedical research as surgical models and in other experiments requiring the use of anesthesia. Isoflurane is a common inhalant anesthetic used in swine that has been shown to alter hematologi...
Swine are commonly used in biomedical research as surgical models and in other experiments requiring the use of anesthesia. Isoflurane is a common inhalant anesthetic used in swine that has been shown to alter hematologic parameters in other species. However, the effects of isoflurane on hematologic parameters of swine over time have not been defined. In this study, we examined the effect of isoflurane anesthesia on hematologic parameters in 29 female Yorkshire/Landrace hybrid domestic swine at 3 timepoints. A secondary objective was to compare hematologic values in isoflurane-anesthetized animals that received intramuscular tiletamine-zolazepam (TZ) or a combination of ketamine-acepromazine-hydromorphone (KAH) for induction. Swine were induced with TZ or KAH, followed by nose cone delivery of 3.5% to 5% isoflurane to facilitate endotracheal intubation, and maintained with 1.75% to 3.5% isoflurane. Venous whole blood was collected for hematologic analysis at baseline upon recumbency after intramuscular administration of TZ or KAH, and at 30 min (T30) and 60 min (T60) of isoflurane administration. There were significant decreases in red blood cell (RBC) count, hematocrit (Hct), and hemoglobin after 30 min of isoflurane anesthesia, and between 30 and 60 min of isoflurane anesthesia. Hct decreased from 35.4% at baseline to 31.8% after 30 min of isoflurane anesthesia, and 31.1% after 60 min of isoflurane anesthesia. The decrease in RBC parameters was accompanied by a significant increase in reticulocyte count at T30 and T60 compared with baseline. When comparing the TZ and KAH groups, Hct and hemoglobin were significantly lower at T30 and T60 in the TZ group, and WBC and neutrophils were significantly higher at T60 in the KAH group. These results indicate that anesthesia alters certain hematologic parameters in swine, thus veterinarians and researchers should take care to avoid misinterpretation of CBCs when blood is collected from anesthetized swine.
Refining In-Cage Enrichment for Specialized Mouse Scenarios.
Oldham S, Minton E, Ford M … +4 more , Phariss H, Luo X, Kastenmayer R, Straley E
J Am Assoc Lab Anim Sci · 2025 Jul · PMID 40675595 · Full text
Environmental enrichment is a critical component of a high-quality animal care and use program to provide opportunities for species-specific behaviors and redirect abnormal repetitive behaviors. We used a scoring system...
Environmental enrichment is a critical component of a high-quality animal care and use program to provide opportunities for species-specific behaviors and redirect abnormal repetitive behaviors. We used a scoring system to review our enrichment for singly housed mice to assess usage of supplied items. Following the confirmation of utilization of the selected enrichment, we applied the scoring system to address 2 cases of abnormal behavior. Repetitive food shredding in CD-1 mice was reduced by both manzanita sticks and running wheels; however, manzanita sticks were selected for operational ease. Focal auricular trauma associated with ear tags in BALB/c mice was decreased when gnawing items were provided, thus slowing the deterioration of ear tag condition. Scoring for all 3 studies focused on use of the enrichment, incorporation into the nest, or reduction of abnormal repetitive behavior. The development of a scoring system permits the objective assessment and selection of enrichment for unique scenarios, thus enhancing animal welfare and permitting a standardized way to evaluate enrichment for specialized projects.
Rodent Pathogen Detection via Testing of Soiled Nesting Material.
Kurtz DM, Angermeier L, Chisolm M … +4 more , Johnston M, Whiteside T, Locklear J, Shi M
J Am Assoc Lab Anim Sci · 2025 Jul · PMID 40675588 · Full text
Murine pathogens affect laboratory animal health and research outcomes, and the prevention of pathogen incursion or the elimination of pathogen outbreaks is paramount. To this end, sensitive methods for pathogen detectio...
Murine pathogens affect laboratory animal health and research outcomes, and the prevention of pathogen incursion or the elimination of pathogen outbreaks is paramount. To this end, sensitive methods for pathogen detection are continually being developed and improved. Environmental health monitoring has become a popular and sensitive method for pathogen detection. Published methods for environmental sampling include the collection and testing of exhaust air filters, exhaust air duct swabs, and swabs or filter media placement in empty cages with soiled bedding. Our study tested soiled, cotton nesting material (Nestlet™) in occupied cages for the detection of nucleic acid from certain, high-prevalence, murine pathogens. Nesting material from cages housing mice positive for mouse norovirus, Helicobacter spp., and Rodentibacter heylii consistently tested positive for these agents. In addition, nesting material from cages housing naïve mice to which soiled bedding from the infected cages was transferred tested positive for these agents more often than testing the mice directly. This study concluded that testing of particulate material (for example, dust) from soiled nesting material is a sensitive detection method for certain, high-prevalence murine pathogens.
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