Advocating for Generalizability: Accepting Inherent Variability in Translation of Animal Research Outcomes

Advancing scientific discovery requires investigators to embrace research practices that increase transparency and disclosure about materials, methods, and outcomes. Several research advocacy and funding organizations have produced guidelines and recommended practices to enhance reproducibility through detailed and rigorous research approaches; however, confusion around vocabulary terms and a lack of adoption of suggested practices have stymied successful implementation. Although reproducibility of research findings cannot be guaranteed due to extensive inherent variables in attempts at experimental repetition, the scientific community can advocate for generalizability in the application of data outcomes to ensure a broad and effective impact on the comparison of animals to translation within human research. This report reviews suggestions, based upon work with National Institutes of Health advisory groups, for improving rigor and transparency in animal research through aspects of experimental design, statistical assessment, and reporting factors to advocate for generalizability in the application of comparative outcomes between animals and humans.

Evaluation of Rodent Diet Stability when Stored in Conditions that Diverge from Guide Parameters

An essential aspect of animal resource programs is the storage and provision of food for a variety of species. Environmental parameters for feed storage conditions (temperature less than 70 °F; relative humidity less than 50%) are recommended in the Guide for the Care and Use of Laboratory Animals, along with aspects of nutrition such as palatability, vermin-control measures, diet quality, and integrity of feed bags. After receiving a suggestion for improvement for environmental conditions in 2 feed storage locations during an AAALAC accreditation visit, we hypothesized that the packaging of contemporary rodent feed could sustain wider environmental variations in temperature and humidity without adverse impact on integrity and palatability. This study evaluated representative feed storage sites across campus buildings to capture the variation in environmental conditions that are inherent to large and diverse animal care programs. Each test storage location held 2 identical bags of feed (same type, lot, and expiration date) that were stored from June to September of 2021; some aspects of the project were repeated during summer 2022 with a similar rodent feed. Baseline nutrients were analyzed from feed samples collected at time 0 (control) and again after 1 and 3mo of storage. The overall nutritional values measured in feed at the end of the study were not significantly different from control values, regardless of test site and variation in environmental parameters. Retinol (as a measure of Vitamin A) was the only component that decreased significantly; however, final retinol levels were consistently above those necessary for appropriate nutrition for mice. Our animal care program stakeholders were briefed on the outcomes of this study with the intent to verify at future AAALAC site visits that our storage conditions are adequate for maintaining the nutritional quality of packaged rodent feed.

Evaluation of Active Warming and Surgical Draping for Perioperative Thermal Support in Laboratory Mice

Surgical procedures are commonly performed using mice but can have major effects on their core body temperature, including development of hypothermia. In this study, we evaluated active perioperative warming with and without surgical draping with adherent plastic wrap to refine practices, improve animal welfare, and optimize research experiments. Mice were randomized into treatment groups (n = 6; 8 CD1 mice per group). Treatments included placement within a small-animal forced-air incubator at 38 ° C for 30 min before surgery (Pre), after surgery (Post), or before and after surgery (Both). To explore the effect of surgical draping, one group received incubator warming before and after surgery in addition to surgical draping (Both/ Drape), whereas another group received surgical draping only without incubator warming (Control/Drape). The final group of mice received neither warming nor draping (Control). Subcutaneous temperature transponders were placed in all mice. Approximately 5 d after transponder placement, mice were anesthetized with ketamine-xylazine and underwent laparotomy. Subcutaneous body temperatures were collected perioperatively from transponders, and rectal temperatures were taken every minute during surgery. For recovery from anesthesia, mice were placed either in a standard cage on a warm water blanket set to 38 °C (100.4 °F) or in the incubator. Subcutaneous body temperatures were significantly higher in mice prewarmed for 30 min (Pre, Both, Both/Drape) as compared with mice that were not prewarmed. Anesthetic recovery times were significantly longer for mice placed in the incubator (Pre, Post, Both, Both/Drape) than for those that did not receive incubator warming (Control, Control/Drape). Mean intraoperative rectal temperatures of Both/Drape mice tended to be greater than those of mice in the Both group, suggesting a warming benefit of surgical draping. Using a forced air incubator and adherent plastic draping mitigated body temperature loss in mice during both surgery and postoperative recovery.

Using Waterless Alcohol-based Antiseptic for Skin Preparation and Active Thermal Support in Laboratory Rats

Rodents are frequently used for models that require surgical procedures. At our institution, laboratory rats are increasingly preferred for investigations of neurologic disorders, cardiovascular interventions, and assessment and treatment of addictive and depressive behaviors. For these types of studies, surgical preparations of the head and neck areas are necessary for catheterization and instrumentation. Based upon our former work in laboratory mice, we sought to improve rat surgery outcomes and confirm the efficacy of a waterless alcohol-based (WAB) antiseptic for skin disinfection prior to incision. In addition, we wanted to investigate whether active warming efforts improved perioperative body temperatures for rats to aid in return to consciousness. Prior to cranial surgical incision and placement in stereotactic equipment, rats were assessed after skin preparation with WAB and after thermal interventions, including prewarming cages for 30 min before anesthesia and delivery of warmed fluid (NaCl) supplementation. Core temperatures were recorded and aerobic culture swabs collected from surgical sites at multiple time points. As previously shown in mice, bacterial counts in rats were effectively diminished by WAB agents. Assessment of intraoperative body temperature trajectories did not identify appreciable differences between control rats and rats that were exposed to prewarming or warmed fluid supplementation or both. However, heavier male rats recovered more rapidly from isoflurane anesthesia than did lighter male and female rats. Although these thermal support measures did not significantly improve anesthetic recovery times in rats, animals warmed for 30 min trended toward a faster return to righting reflex after exposure to isoflurane. These findings confirm that WAB antiseptic is an acceptable option for skin preparation in rats and suggest that continued evaluation of thermal interventions remains of interest for improved outcomes in rat surgery.

Vaporized Hydrogen Peroxide Decontamination of N95 Respirators in a Dedicated Animal Research Facility for Reuse During a Novel Coronavirus Pandemic

Introduction

During the COVID-19 pandemic, health care systems and safety providers have faced an unprecedented challenge of limited access to personal protective equipment (PPE) to conduct patient and public care. In federal emergencies, reuse of PPE after disinfection can occur by processes, like vaporized hydrogen peroxide (VHP), recommended by the Centers for Disease and Control and Prevention. We identified a vacant animal holding facility at our institution to repurpose into a regional VHP decontamination center.

Methods

The facility is a multiroom, 20 000 ft2 building with control of HVAC to adjust to VHP conditional requirements. H2O2 was delivered to rooms using robotic HaloFoggers, dispersing H2O2 vapor and increasingly concentrated microdroplets as a fog for a timed period based on cubic footage of rooms.

Results

Fogging cycles eliminated 6-log Geobacillus stearothermophilus up to 7 days postcycle. Functional efficacy of treated N95s was confirmed by fit tests of institutional personnel. Signage, process flow mapping, and training materials facilitated ease of workflow and adherence to safety expectations within the building.

Discussion and Conclusion

Our study determined that a variety of N95 respirator types and sizes were able to be cleared of potential bacterial and viral agents using VHP in a controlled fog/dwell/exhaust cycle. This repurposed animal facility has the capacity to decontaminate up to 6700 respirators daily, which will address the predicted surge of COVID-19 cases in the state, and ultimately allow each respirator to be reused multiple times. There is no other public site in the region with our capacity to offset the continued supply chain issues for PPE needs.

Nonexperimental Xenobiotics: Unintended Consequences of Intentionally Administered Substances in Terrestrial Animal Models

Review of the use of nonexperimental xenobiotics in terrestrial animal models and the potential unintended consequences of these compounds, including drug-related side effects and adverse reactions.

Investigator Engagement: Somewhat Radical Considerations on Practices to Improve Animal Care Program Compliance

The authors discuss approaches to bolster investigator engagement, inviting investigators to be partners within the Animal Care Program. Regulatory burden in animal research endeavors continues to be reviewed and critiqued; therefore, this article intends to encourage Animal Care Programs to promote transparency and incorporation of unique educational training initiatives to tailor and focus compliance efforts across research programs. Borrowing from concepts of patient engagement, adherence, and enrollment efforts within the medical profession, it is likely that gains in trust, understanding, and communication between stakeholders within animal programs can be achieved without excessive efforts to alter existing approaches. Institutions will continue to be challenged to balance animal welfare expectations with promotion of research missions. This article provides a framework for somewhat radical ideas, including the use of collaborative orientations, assistance with self-evaluations, timely self-reporting, and meaningful and directed trainings, that are all aimed to resonate in contemporary animal care programs and foster investigator engagement in ongoing compliance efforts.

Effects of Rodent Thermoregulation on Animal Models in the Research Environment

To best promote animal wellbeing and the efficacy of biomedical models, scientific, husbandry, and veterinary professionals must consider the mechanisms, influences, and outcomes of rodent thermoregulation in contemporary research environments. Over the last 2 decades, numerous studies have shown that laboratory mice and rats prefer temperatures that are several degrees warmer than the environments in which they typically are housed within biomedical facilities. Physiologic changes to rodents that are cage-housed under standard temperatures (20 to 26 °C) are attributed to 'cold stress' and include alterations in metabolism, cardiovascular parameters, respiration, and immunologic function. This review article describes common behavioral and physiologic adaptations of laboratory mice and rats to cold stress within modern vivaria, with emphasis on environmental enrichment and effects of anesthesia and procedural support efforts. In addition, potential interventions and outcomes for rodents are presented, relative to the importance of repeating and reproducing experiments involving laboratory rodent research models of human disease.

Comparison of Aqueous and Alcohol-based Agents for Presurgical Skin Preparation Methods in Mice

Preparing the skin of rodents for surgery often involves multiple applications of antiseptic agents. However, fewer applications may achieve the same antiseptic outcome. We evaluated the antimicrobial efficacy and effects on intraoperative body temperature of various surgical scrub agents, including novel waterless alcohol-based (WAB) options. Prior to ventral laparotomy, female C57BL/6 mice were treated with 0.9% saline (control); 70% ethanol; 10% povidone-iodine alternated with saline or 70% ethanol; 2% chlorhexidine digluconate alternated with saline or 70% ethanol; or 1 of 3 WAB products-commercial surgical scrub A, commercial surgical scrub B, or a common commercial hand sanitizer. Core temperatures were recorded, and aerobic culture swabs were collected from the surgical site at multiple time points. Intraoperative temperature trajectories for animals treated with scrub B, 10% povidone-iodine with saline, or hand sanitizer did not differ from saline (control). Temperature trajectories of mice treated with other scrub agents did differ significantly from saline. Bacteria were not detected at the operative site after 3 scrubs of 70% ethanol or 10% povidone-iodine alternated with ethanol, 2 scrubs of scrub A or B, 1 scrub of hand sanitizer, and both 1 and 3 scrubs of 2% chlorhexidine alternated with ethanol. Scrub B and 2% chlorhexidine-ethanol demonstrated prolonged antibacterial efficacy. Histology of corresponding haired skin sections revealed no differences in postoperative healing between groups, and no postoperative infections occurred. These results indicate that various novel WAB disinfectants, particularly scrub B (61% ethanol and 1% chlorhexidine gluconate), mitigate intraoperative temperature effects associated with several traditional agents and combinations. Furthermore, reduction of skin bacterial load without adverse effects on healing was seen with fewer than triplicate applications of most tested agents. Ultimately effective skin preparation can be achieved by using only 1 or 2 applications of scrub, thus rendering the triplicate skin-prep method unnecessary in laboratory mice.

Quantification of Induced Hypothermia from Aseptic Scrub Applications during Rodent Surgery Preparation

Laboratory mice (Mus musculus) are prone to develop hypothermia during anesthesia for surgery, thus potentially impeding anesthetic recovery, wound healing, and future health. The core body temperatures of isoflurane-anesthetized mice are influenced by the choice of supplemental heat sources; however, the contribution of various surgical scrubs on the body temperatures of mice under gas anesthesia has not been assessed. We sought to quantify the effect of using alcohol (70% isopropyl alcohol [IPA]) compared with saline to rinse away surgical scrub on the progression of hypothermia in anesthetized mice (n = 47). IPA, room-temperature saline, or warmed saline (37 °C) was combined with povidone-iodine and then assessed for effects on core (rectal) and surface (infrared) temperatures. Agents were applied to a 2×2-cm shaved abdominal area of mice maintained on a water-recirculating blanket (at 38 °C) under isoflurane anesthesia (1.5% to 2.0% at 0.6 L/min) for 30 min. Although all scrub regimens significantly decreased body temperature at the time of application, treatments that included povidone-iodine led to the coldest core temperatures, which persisted while mice were anesthetized. Compared with room-temperature saline and when combined with povidone-iodine, warming of saline did not ameliorate heat loss. IPA alone demonstrated the most dramatic cooling of both surface and core readings at application but generated an unanticipated warming (rebound) phase during which body temperatures equilibrated with those of controls within minutes of application. Although alcohol is inappropriate as a stand-alone agent for surgical skin preparation, IPA is a viable alternative to saline-based rinses in this context, and its use should be encouraged within institutional guidance for rodent surgical procedures without concern for prolonged hypothermia in mice.

Quantification of Induced Hypothermia from Aseptic Scrub Applications during Rodent Surgery Preparation

Laboratory mice (Mus musculus) are prone to develop hypothermia during anesthesia for surgery, thus potentially impedinganesthetic recovery, wound healing, and future health. The core body temperatures of isoflurane-anesthetized mice areinfluenced by the choice of supplemental heat sources; however, the contribution of various surgical scrubs on the bodytemperatures of mice under gas anesthesia has not been assessed. We sought to quantify the effect of using alcohol (70%isopropyl alcohol [IPA]) compared with saline to rinse away surgical scrub on the progression of hypothermia in anesthetizedmice (n = 47). IPA, room-temperature saline, or warmed saline (37 °C) was combined with povidone-iodine and thenassessed for effects on core (rectal) and surface (infrared) temperatures. Agents were applied to a 2×2-cm shaved abdominalarea of mice maintained on a water-recirculating blanket (at 38 °C) under isoflurane anesthesia (1.5% to 2.0% at 0.6 L/min)for 30 min. Although all scrub regimens significantly decreased body temperature at the time of application, treatments thatincluded povidone-iodine led to the coldest core temperatures, which persisted while mice were anesthetized. Comparedwith room-temperature saline and when combined with povidone-iodine, warming of saline did not ameliorate heat loss.IPA alone demonstrated the most dramatic cooling of both surface and core readings at application but generated an unanticipatedwarming (rebound) phase during which body temperatures equilibrated with those of controls within minutes ofapplication. Although alcohol is inappropriate as a stand-alone agent for surgical skin preparation, IPA is a viable alternativeto saline-based rinses in this context, and its use should be encouraged within institutional guidance for rodent surgicalprocedures without concern for prolonged hypothermia in mice.

Intraperitoneal Continuous-Rate Infusion for the Maintenance of Anesthesia in Laboratory Mice (Mus musculus)

Intraperitoneal injectable anesthetics are often used to achieve surgical anesthesia in laboratory mice. Because bolus redosing of injectable anesthetics can cause unacceptably high mortality, we evaluated intraperitoneal continuous-rate infusion (CRI) of ketamine with or without xylazine for maintaining surgical anesthesia for an extended period of time. Anesthesia was induced in male C57BL/6J mice by using ketamine (80 mg/kg) and xylazine (8 mg/kg) without or with acepromazine at 0.1 mg/kg or 0.5 mg/kg. At 10 min after induction, CRI for 90 min was initiated and comprised 25%, 50%, or 100% of the initial ketamine dose per hour or 50% of the initial doses of both ketamine and xylazine. Anesthetic regimens were compared on the basis of animal immobility, continuous surgical depth of anesthesia as determined by the absence of a pedal withdrawal reflex, and mortality. Consistent with previous studies, the response to anesthetics was highly variable. Regimens that provided the longest continuous surgical plane of anesthesia with minimal mortality were ketamine-xylazine-acepromazine (0.1 mg/kg) with CRI of 100% of the initial ketamine dose and ketamine-xylazine-acepromazine (0.5 mg/kg) with CRI of 50% of the initial ketamine and xylazine doses. In addition, heart rate and respiratory rate did not increase consistently in response to a noxious stimulus during CRI anesthesia, even when mice exhibited a positive pedal withdrawal reflex, suggesting that these parameters are unreliable indicators of anesthetic depth during ketamine-xylazine anesthesia in mice. We conclude that intraperitoneal CRI anesthesia in mice prolongs injectable anesthesia more consistently and with lower mortality than does bolus redosing.

Evaluation of Presurgical Skin Preparation Agents in African Clawed Frogs (Xenopus laevis)

Despite the routine collection of oocytes from African clawed frogs (Xenopus laevis) for use in research, few studies have evaluated methods for preparing their skin for surgery. We evaluated 3 skin preparatory agents by examining their antibacterial efficacy and the gross and microscopic appearance of Xenopus skin after exposure. Frogs (n = 14) were sedated and treated (contact time, 10 min) with 0.9% sterile NaCl on one-half of the ventrum and with 0.5% povidone-iodine or 0.75% chlorhexidine on the other half. Bacterial cultures were obtained before and after skin treatment; bacteria were identified by mass spectrometry. To assess inflammation and degenerative changes, the incision sites were photographed and biopsied at 0, 1, and 7 d after surgery. We isolated at least 22 genera of bacteria from the skin of our frog population (mean ± SE, 5.21 ± 0.82 genera per frog). Iodine (2.00 ± 0.44 genera) and chlorhexidine (0.29 ± 0.76 genera) both had greater antimicrobial activity than did saline. Skin erythema did not correlate with treatment group. Histologic evidence of epidermal degeneration and necrosis was greater on days 1 and 7 after chlorhexidine treatment than after iodine or saline. In addition, frogs treated with chlorhexidine had a higher incidence of clinical illness associated with the exposure site. In summary, although chlorhexidine has adequate antimicrobial activity against organisms on X. laevis skin, it leads to skin damage and subsequent clinical complications. We therefore do not recommend chlorhexidine as a preoperative preparation agent in Xenopus.

Intraperitoneal Injection of Ethanol for the Euthanasia of Laboratory Mice (Mus musculus) and Rats (Rattus norvegicus)

Compassion, professional ethics, and public sensitivity require that animals are euthanized humanely and appropriately under both planned and emergent situations. According to the 2013 AVMA Guidelines for the Euthanasia of Animals, intraperitoneal injection of ethanol is "acceptable with conditions" for use in mice. Because only limited information regarding this technique is available, we sought to evaluate ethanol by using ECG and high-definition video recording. Mice (n = 85) and rats (n = 16) were treated with intraperitoneal ethanol (70% or 100%), a positive-control agent (pentobarbital-phenytoin combination [Pe/Ph]), or a negative-control agent (saline solution). After injection, animals were assessed for behavioral and physiologic responses. Pain-assessment techniques in mice demonstrated that intraperitoneal injection of ethanol was not more painful than was intraperitoneal Pe/Ph. Median time to loss of consciousness for all mice that received ethanol or Pe/Ph was 45 s. Median time to respiratory arrest was 2.75, 2.25, and 2.63 min, and time (mean ± SE) to cardiac arrest was 6.04 ± 1.3, 2.96 ± 0.6, and 4.03 ± 0.5 min for 70% ethanol, 100% ethanol, and Pe/Ph, respectively. No mouse that received ethanol or Pe/Ph regained consciousness. Although successful in mice, intraperitoneal ethanol at the doses tested (9.2 to 20.1 g/kg) was unsuitable for euthanasia of rats (age, 7 to 8 wk) because of the volume needed and prolonged time to respiratory effects. For mice, intraperitoneal injection of 70% or 100% ethanol induced rapid and irreversible loss of consciousness, followed by death, and should be considered as "acceptable with conditions."

Comparison of Heart Rate and Blood Pressure with Toe Pinch and Bispectral Index for Monitoring the Depth of Anesthesia in Piglets

Determining depth of anesthesia (DOA) is a clinical challenge in veterinary medicine, yet it is critical for the appropriate oversight of animals involved in potentially painful experimental procedures. Here, we investigated various parameters used to monitor conscious awareness during surgical procedures and refined the application of noxious stimuli to anesthetized animals. Specifically we used a common stimulus, a compressive toe pinch (TP), to determine physiologic changes that accompanied a positive or negative motion response in isoflurane-anesthetized piglets. A positive response was defined as any reflexive withdrawal, whereas a negative response was defined as the absence of motion after stimulation. We also assessed the utility of the bispectral index (BIS) for its ability to predict a motion response to TP. The average of BIS values over 1 min (BISmean) was recorded before and after TP. In piglets with a positive response to TP, heart rate (HR), but not blood pressure (BP), increased significantly, but receiver operating characteristic (ROC) analysis revealed that HR was not a sensitive, specific predictor of TP motion response. Both before and after TP, BISmean was a strong predictor of a positive motion response. We conclude that HR and noninvasive BP changes are not clinically reliable indicators of anesthetic depth when assessed immediately after a peripherally applied compressive force as an indicator stimulus; however, BISmean and response TP are acceptable for assessing DOA in piglets maintained under isoflurane anesthesia.

The Effects of Acute Blood Loss for Diagnostic Bloodwork and Fluid Replacement in Clinically Ill Mice

Despite the great value of diagnostic bloodwork for identifying disease in animals, the volume of blood required for these analyses limits its use in laboratory mice, particularly when they are clinically ill. We sought to determine the effects of acute blood loss (ABL) following blood collection for diagnostic bloodwork in healthy mice compared with streptozotocin-induced diabetic and dextran sulfate sodium (DSS)-treated dehydrated mice. ABL caused several mild changes in the control mice, with significant decreases in body weight, temperature, and activity in both experimental groups; increased dehydration and azotemia in the DSS-treated mice; and a significant drop in the blood pressure of the diabetic mice. To determine whether these negative outcomes could be ameliorated, we treated mice with intraperitoneal lactated Ringers solution either immediately after or 30 min before ABL. Notably, preABL administration of fluids helped prevent the worsening of the dehydration and azotemia in the DSS-treated mice and the changes in blood pressure in the diabetic mice. However, fluid administration provided no benefit in control of blood pressure when administered after ABL in the diabetic mice. Furthermore, fluid therapy did not prevent ABL-induced drops in body weight and activity. Although one mouse not receiving fluid therapy became moribund at the 24-h time point, no animals died during the 24-h study. This investigation demonstrates that blood for diagnostic bloodwork can be collected safely from clinically ill mice and that preemptive fluid therapy mitigates some of the negative changes associated with this blood loss.

Type, duration, and incidence of pathologic findings after retroorbital bleeding of mice by experienced and novice personnel

Retroorbital blood collection is a common technique in laboratory rodents due to the ease with which it can be performed and the sample volumes obtained for subsequent blood analyses. However, its use has been discouraged recently due to aesthetic discomfort and anecdotal reports of potential for ocular injury during blood collection. We hypothesized that a single standardized session of in-person training would be sufficient to learn the appropriate technique and minimize the likelihood for adverse outcomes. Experienced instructors (n = 2) conducted hands-on training classes to teach novice personnel (n = 40) to perform this procedure. Blood was collected from anesthetized mice (n = 40) via a capillary tube first placed at the medial canthus of the right eye and then advanced into the retroorbital space; the left retroorbital spaces served as unmanipulated controls. For comparison, the experienced instructors similarly collected blood from 40 additional mice. The tube could be inserted only once in each mouse, with the goal of obtaining 50 to 100 μL blood. Overall, 79 of 80 mice (98.8%) showed normal body condition, posture, and behavior throughout the 14-d study. Thus, any clinical observation scores pertained specifically to ocular lesions, which occurred at least once after sampling in 43 (53.8%) of the mice. Clinical and histopathologic scores of mice after bleeding did not differ between experienced and novice personnel. We conclude that a coordinated hands-on training program can provide consistent and sufficient instruction for research personnel to conduct retroorbital blood collection with competence in anesthetized laboratory mice.

Adverse effects of vapocoolant and topical anesthesia for tail biopsy of preweanling mice

Tail biopsy of laboratory mice for genotyping purposes has been studied extensively to develop refinements for this common procedure. Our prior work assessed tail vertebral development in different mouse strains (age, 3 to 42 d) and analyzed behavior and activity in mice (age, 21 to 45 d) biopsied under isoflurane anesthesia. To assess the effects of biopsy on preweanling mice, we here evaluated BALB/cAnNCrl mice (n = 80; age, 18 to 21 d) that received topical vapocoolant (ethyl chloride), topical anesthetic (Cetacaine), or isoflurane anesthesia before undergoing a 5-mm or sham biopsy. Control mice did not receive any anesthetic intervention. Regardless of the anesthetic used, acute observation scores indicative of distress were increased at 10 min after biopsy, and locomotor activity was decreased, in biopsied compared with control mice. Acute observation scores at 10 min after biopsy were higher in mice that received ethyl chloride compared with isoflurane or no anesthesia. Microscopic analysis revealed that inflammatory changes in the distal tail remained elevated until 7 d after biopsy and were higher in tails exposed to ethyl chloride. Our findings indicate that vapocoolant, topical anesthesia, and inhaled isoflurane do not enhance the wellbeing of preweanling mice undergoing tail biopsy. Due to the lack of appreciable benefits and the presence of notable adverse effects, using vapocoolants or Cetacaine for this tail biopsy procedure in laboratory mice is unadvisable and we encourage the removal of these agents from institutional tail biopsy guidelines.

Biology and Diseases of Hamsters

The hamster species used as research models include the Syrian (golden), Mesocricetus auratus; the Chinese (striped-back), Cricetulus griseus; the Armenian (gray), C. migratorius; the European, Cricetus cricetus; and the Djungarian, Phodopus campbelli (Russian dwarf) and P. sungorus (Siberian dwarf). Hamsters are classified as members of the order Rodentia, suborder Myomorpha, superfamily Muroidea and in family Cricetidae. Animals in this family are characterized by large cheek pouches, thick bodies, short tails, and an excess of loose skin. They have incisors that erupt continuously and cuspidate molars that do not continue to grow ((I 1/1, C 0/0, PM 0/0, M 3/3) × 2 = 16). In 2010, it was reported that approximately 146,000 hamsters were used in research in the United States (United States Department of Agriculture, 2010).

Dose regimens, variability, and complications associated with using repeat-bolus dosing to extend a surgical plane of anesthesia in laboratory mice

Extending a surgical plane of anesthesia in mice by using injectable anesthetics typically is accomplished by repeat-bolus dosing. We compared the safety and efficacy of redosing protocols administered either during an anesthetic surgical plane (maintaining a continuous surgical plane, CSP), or immediately after leaving this plane (interrupted surgical plane, ISP) in C57BL/6J mice. Anesthesia was induced with ketamine, xylazine, and acepromazine (80, 8, and 1 mg/kg IP, respectively), and redosing protocols included 25% (0.25K), 50% (0.5K), or 100% (1.0K) of the initial ketamine dose or 25% (0.25KX) or 50% (0.5KX) of the initial ketamine-xylazine dose. In the ISP group, the surgical plane was extended by 13.8 ± 2.1 min (mean ± SEM) after redosing for the 0.25K redose with 50% returning to a surgical plane, 42.7 ± 4.5 min for the 0.5K redose with 88% returning to a surgical plane, and 44.3 ± 15.4 min for the 1.0K redose, 52.8 ± 7.2 min for the 0.25KX redose, and 45.9 ± 2.9 min for the 0.5KX redose, with 100% of mice returning to a surgical plane of anesthesia in these 3 groups. Mortality rates for ISP groups were 0%, 12%, 33%, 12%, and 18%, respectively. Mice in CSP groups had 50% mortality, independent of the repeat-dosing protocol. We recommend redosing mice with either 50% of the initial ketamine dose or 25% of the initial ketamine-xylazine dose immediately upon return of the pedal withdrawal reflex to extend the surgical plane of anesthesia in mice, optimize the extension of the surgical plane, and minimize mortality.

Antibiotic administration in the drinking water of mice

Although antibiotics frequently are added to the drinking water of mice, this practice has not been tested to confirm that antibiotics reach therapeutic concentrations in the plasma of treated mice. In the current investigation, we 1) tested the stability of enrofloxacin and doxycycline in the drinking water of adult, female C57BL/6 mice; 2) measured the mice's consumption of water treated with enrofloxacin, doxycycline, amoxicillin, or trimethoprim-sulfamethoxazole; and 3) used HPLC to measure plasma antibiotic concentrations in mice that had ingested treated water for 1 wk. Plasma concentrations of antibiotic were measured 1 h after the start of both the light and dark cycle. The main findings of the study were that both enrofloxacin and nonpharmaceutical, chemical-grade doxycycline remained relatively stable in water for 1 wk. In addition, mice consumed similar volumes of antibiotic-treated and untreated water. The highest plasma antibiotic concentrations measured were: enrofloxacin, 140.1 ± 10.4 ng/mL; doxycycline, 56.6 ± 12.5 ng/mL; amoxicillin, 299.2 ± 64.1 ng/mL; and trimethoprim-sulfamethoxazole, 5.9 ± 1.2 ng/mL. Despite the stability of the antibiotics in the water and predictable water consumption by mice, the plasma antibiotic concentrations were well below the concentrations required for efficacy against bacterial pathogens, except for those pathogens that are exquisitely sensitive to the antibiotic. The findings of this investigation prompt questions regarding the rationale of the contemporary practice of adding antibiotics to the drinking water of mice for systemic antibacterial treatments.

Comparison of thermoregulatory devices used during anesthesia of C57BL/6 mice and correlations between body temperature and physiologic parameters

General anesthesia affects several body systems, including thermoregulation. Decreased body temperature during anesthesia has potential negative effects, including delayed recovery to consciousness. Thermoregulatory support devices are used to maintain temperature in anesthetized rodents. We analyzed 2 novel thermoregulatory devices, thermogenic gel packs and reflective foils, to compare their effectiveness in maintaining temperatures with that of a standard circulating-warm-water blanket (CWWB) in C57BL/6 mice. Mice were grouped randomly: control (no thermal support), reflective foil, gel pack, gel pack plus reflective foil, CWWB on medium setting, CWWB on high setting, and CWWB on high setting plus reflective foil. Mice were anesthetized with isoflurane for 30 min, and temperature and heart and respiratory rates were monitored. Results indicated that the temperatures of mice with reflective foil only (start temperature, 36.2 ± 0.38 °C; end temperature, 28.8 ± 0.78 °C) did not differ significantly from those of control mice; however, the inclusion of foil heightened thermogenic properties when combined with other devices. Thermogenic gel packs and CWWB on high setting, both with and without reflective foil, caused significant temperature increases (that is, 1.6 °C to 4.4 °C) in mice. CWWB on medium setting (blanket temperature, 37.5 °C) maintained mice at temperatures within 1 °C of the 36.1 °C baseline. Strong correlations existed between temperature, heart and respiratory rates, and recovery time to consciousness. This information provides guidance regarding the use of thermoregulatory devices in anesthetized rodents and demonstrates the effect of maintaining a consistent core temperature on physiologic parameters.

Weight loss and reduced body temperature determine humane endpoints in a mouse model of ocular herpesvirus infection

Herpes simplex virus (HSV) has been studied in well-established mouse models to generate latently infected animals for investigations into viral pathogenesis, latency mechanisms, and reactivation. Mice exhibit clinical signs of debilitating infection, during which time they may become severely ill before recovery or die spontaneously. Because the cohort of mice that does survive provides valuable data on latency, there is keen interest in developing methodologies for earlier detection and treatment of severe disease to ultimately increase survival rates. Here, BALB/c mice were inoculated ocularly with either a wildtype (LAT(+)) or mutant (LAT(-)) strain of HSV1. Mice were monitored daily through day 30 after infection; trigeminal ganglia were harvested at day 60 to assess viral DNA load. Cages were provided with nesting material, and fluid supplementation was administered to mice with body temperatures of 35 °C or lower, as measured by subcutaneous microchip thermometry. The results showed that infected mice with temperatures less than 34.5 °C did not recover to normothermia and were euthanized or spontaneously died, regardless of infective viral strain. By using a combination of criteria including body temperature (less than 34.5 °C) and weight loss (more than 0.05 g daily) for removal of animals from the study, approximately 98% of mice that died spontaneously could have been euthanized prior to death, without concern of potential recovery to the experimental endpoint (100% specificity). Frequent monitoring of alterations to general wellbeing, body temperature, and weight was crucial for establishing humane endpoints in this ocular HSV model.

Risk-based immunization policies and tuberculosis screening practices for animal care and research workers in the United States: survey results and recommendations

A national survey was conducted to assess immunization practices and tuberculosis screening methods for animal care and research workers in biomedical settings throughout the United States. Veterinarians (n = 953) were surveyed via a web-based mechanism; completed surveys (n = 308) were analyzed. Results showed that occupational health and safety programs were well-developed, enrolling veterinary, husbandry, and research staff at rates exceeding 90% and involving multiple modalities of health assessments and risk communication for vaccine-preventable diseases. Most (72.7%) institutions did not store serum samples from animal research personnel. More than half of the institutions housed nonhuman primates and maintained tuberculosis screening programs, although screening methods varied. Immunization protocols included various recommended or required vaccines that differed depending on job duties, type of institution, and nature of scientific programs. A single case of an identified vaccine-preventable illness in a laboratory worker was noted. Tetanus toxoid was the predominant vaccine administered (91.7%) to animal care and research workers, followed by hepatitis B (54.8%), influenza (39.9%), and rabies (38.3%). For some immunization protocols, an inconsistent rationale for administration was evident. Indications that animal care and research workers are unprotected from work-related etiologic agents did not emerge from this survey; rather, existing guidelines from the Advisory Committee on Immunization Practices and available biologics seem sufficient to address most needs of the laboratory animal research community. Institutions should commit to performance-based standards in parallel with context-specific risk assessment methods to maintain occupational health and safety programs and practices appropriate to their needs.

Behavioral and activity assessment of laboratory mice (Mus musculus) after tail biopsy under isoflurane anesthesia

Contemporary laboratory animal guidance suggests that tail biopsy of laboratory mice can be performed before 21 d of age without anesthesia, whereas older mice must receive anesthesia before biopsy. Our objective was to determine whether administration of isoflurane anesthesia before tail biopsy produced a measurable effect on the behavior of mice (n = 196). We evaluated C57BL/6 and BALB/c mice at 21 to 24 (weaning), 28 to 31 (delayed weaning), and 42 to 45 (adult) d of age. Mice were observed at the time of biopsy and then twice within the first hour after a sham or tail biopsy. Anxiety-like responses were assessed by using an elevated plus-maze. Activity was evaluated remotely for 120 min. Isoflurane did not diminish acute responses to tail biopsy in mice 31 d or younger compared with sham-biopsied animals but had a significant effect in C57BL/6 biopsied adult mice. In addition, mice of all ages and strains that received anesthesia, regardless of biopsy, spent more time in the enclosed maze arms and had decreased activity up to 5 h after isoflurane exposure. Although tail biopsy should be performed in young mice to avoid transection of distal mature vertebrae, our experimental paradigm indicates that isoflurane anesthesia does not appreciably enhance wellbeing over that of mice biopsied without anesthesia at weaning ages. The influence of inhaled isoflurane was demonstrable and indicated that acute and prolonged alterations in anxiety and activity must be considered when interpreting the impact of anesthesia on tail biopsy across various ages and strains of laboratory mice.

Evaluation of an inhouse rapid ELISA test for detection of giardia in domestic sheep (Ovis aries)

Sheep (Ovis aries) are increasingly used at our institution as models of human disease. Within the research environment, routine husbandry and handling of sheep has potential for transmission of zoonotic agents, including Giardia. The prevalence of Giardia in sheep may approach 68%. Classic diagnostic testing involves microscopic examination for fecal cysts or trophozoites; however, limitations of microscopy include time, labor, and potential false-negative results due to intermittent shedding. We wished to determine whether a commercial rapid ELISA used for Giardia detection in dogs and cats could be used in sheep. Fecal samples collected from sheep (n = 93) were tested with a combination of 6 methods: reference laboratory fecal flotation, reference laboratory ELISA, inhouse fecal flotation, and commercially available tests (enzyme immunoassay, direct fluorescence antibody assay, and rapid ELISA). Prevalence of Giardia infection in facility sheep was 11.8% (11 of 93 animals). Of the 11 samples considered positive, 3 were confirmed by multiple testing methods, and 5 were positive by microscopy alone. Inhouse fecal flotation for 8 samples was positive on only 1 of 2 consecutive testing days. The rapid ELISA test exhibited 0% sensitivity for sheep giardiasis. Overall, the examined methods had low sensitivities and low positive predictive values. Despite limitations, microscopic analysis of repeat fecal samples remained the most accurate diagnostic method for ovine giardiasis among the methods tested.

Development and implementation of multimedia content for an electronic learning course on rodent surgery

The development of new rodent models of human disease and advances in surgical equipment and technologies have increased the demand for expertise in rodent surgery. Because of the limited availability of rodent surgical training courses, electronic (e-) learning is presented as an alternative to in-person education and as a means to hone the expertise of current surgeons in biomedical research, similar to e-learning applications for human surgery training. Translating this model to the biomedical research field provides participants with an opportunity to train themselves on rodent surgical techniques prior to operating on live models. An e-learning rodent surgery course was incorporated into a training class of undergraduate (n = 39) and graduate (n = 12) laboratory animal students, and a portion of the course was presented to laboratory animal professionals (n = 15). The effectiveness of the method was evaluated using written examination and postcourse surveys. The exam data demonstrated that the e-learning course transferred knowledge comparable to a lecture course on surgery that was presented in-person. Students responded favorably to videos, step-by-step photographs of surgical procedures, and the ready accessibility of the course. Critiques included the need to improve video resolution and quality of the voice-overs. These results support the continued development and implementation of electronic rodent surgical technique courses for use in laboratory animal and biomedical research communities.

Guinea pig adenovirus infection does not inhibit cochlear transfection with human adenoviral vectors in a model of hearing loss

Routine surveillance of guinea pigs maintained within a barrier facility detected guinea pig adenovirus (GPAdV) in sentinel animals. These guinea pigs served as models of induced hearing loss followed by regeneration of cochlear sensory (hair) cells through transdifferentiation of nonsensory cells by using human adenoviral (hAV) gene therapy. To determine whether natural GPAdV infection affected the ability of hAV vectors to transfect inner ear cells, adult male pigmented guinea pigs (n = 7) were enrolled in this study because of their prolonged exposure to GPAdV-seropositive conspecifics. Animals were deafened chemically (n = 2), received an hAV vector carrying the gene for green fluorescent protein (hAV-GFP) surgically without prior deafening (n = 2), or were deafened chemically with subsequent surgical inoculation of hAV-GFP (n = 3). Cochleae were evaluated by using fluorescence microscopy, and GFP expression in supporting cells indicated that the hAV-GFP vector was able to transfect inner ears in GPAdV-seropositive guinea pigs that had been chemically deafened. Animals had histologic evidence of interstitial pneumonia, attributable to prior infection with GPAdV. These findings confirmed that the described guinea pigs were less robust animal models with diminished utility for the overall studies. Serology tests confirmed that 5 of 7 animals (71%) were positive for antibodies against GPAdV at necropsy, approximately 7 mo after initial detection of sentinel infection. Control animals (n = 5) were confirmed to be seronegative for GPAdV with clinically normal pulmonary tissue. This study is the first to demonstrate that natural GPAdV infection does not negatively affect transfection with hAV vectors into guinea pig inner ear cells, despite the presence of other health complications attributed to the viral infection.

Humidity and cage and bedding temperatures in unoccupied static mouse caging after steam sterilization

Contemporary rodent caging and equipment often are sterilized by steam autoclaves prior to use in facilities. This work assessed the microenvironment of unoccupied static mouse cages after steam sterilization to determine when internal temperatures had cooled to levels appropriate for rodent housing. Polycarbonate static cages containing food and corncob bedding were stacked (10 rows x 7 columns) in duplicate (front and back; n = 140 cages) on a storage truck and autoclaved to 249 degrees F (121 degrees C). Cages (n = 6) were assessed to represent top, middle, and bottom rows and edges of columns. After cage sterilization, hygrothermometers were placed in cages to measure internal cage temperature (IT), bedding temperature (BT), and cage humidity (CH) every 10 min for 150 min. At time 0, there were no significant differences in averaged temperatures or humidity across cage locations: IT, 95.9 degrees F; BT, 109.8 degrees F; and CH, 84.1%. Over time, significant positional effects occurred. Whereas IT and BT for cages in the center row cooled more slowly than those on the bottom row, CH in top row cages decreased more quickly compared with other cages. After 150 min, the average measures overall were IT, 75.8 degrees F; BT, 77.9 degrees F; and CH, 82.4%. Comparison of the overall measures at 150 min with those of cages cooled overnight (IT, 72.4 degrees F; BT, 71.0 degrees F; and CH, 49%) and cages housing mice (IT, 72.2 degrees F; BT, 70.7 degrees F; and CH, 82%) indicated that a poststerilization cooling period of greater than 2.5 h was necessary to achieve permissible rodent housing conditions at our institution, particularly with corncob bedding autoclaved within the cage.

Enoxaparin treatment of spontaneous deep vein thrombosis in a chronically catheterized rhesus macaque (Macaca mulatta)

A chronically catheterized 14-y-old male rhesus macaque (Macaca mulatta) was reported for recurrent scrotal swelling. The scrotum was enlarged and warm to touch, and associated skin was noted to be lichenified on physical examination. The penis could not be extruded due to preputial swelling. Results from the following diagnostic tests were all unremarkable or within normal limits: scrotal aspirate, hematology, serum biochemistries, urinalysis, and radiography of the thorax, scrotum, and abdomen. Ultrasonography of lower extremities identified thrombi in bilateral iliac veins and left femoral vein. Collateral circulation surrounding the left femoral vein permitted some compensatory venous return. The left femoral vein of this animal had been catheterized approximately 2 mo before initial presentation. A coagulation panel revealed a positive D-dimer test, indicative of elevated levels of fibrin degradation products due to active thrombus breakdown. Enoxaparin sodium, a low-molecular-weight heparin for human use, was administered at 20 mg subcutaneously once daily for 10 d to treat occlusive venous thrombi. After enoxaparin treatment, the edema was greatly decreased. To achieve complete resolution, a second course of enoxaparin was administered 2 months after the first. Ultrasonography of the pelvic vasculature 6 mo after completion of therapy showed marked thrombus resolution, allowing for bilateral patency in the iliac and femoral veins. Follow-up evaluation revealed that D-dimer values were negative as well. This case demonstrates the novel application of the human medication enoxaparin to treat clinical signs of deep vein thrombosis in a chronically catheterized rhesus macaque.

Evaluation of tail biopsy collection in laboratory mice (Mus musculus): vertebral ossification, DNA quantity, and acute behavioral responses

A preferred method to genotype genetically engineered mice is through collection of distal tail tissue (tail biopsy) followed by DNA isolation. Currently, general or local anesthesia (or both) is recommended for biopsy after 3 wk of age, the time after which tail vertebrae are considered to be ossified. Our objective was to rigorously evaluate vertebral development, DNA content, and acute behavioral responses at different ages by harvesting tail biopsies of different lengths. We evaluated laboratory mice from 5 inbred strains and 1 outbred stock at each of 12 ages (3 to 42 d of age). Biopsies of 5-, 10-, and 15-mm lengths were obtained. Vertebrae were graded according to level of ossification by using complementary modalities of high-resolution microradiography, microcomputed tomography, and histology. Vertebral development progressed at different rates among the strains, with mature tail vertebrae containing endplates detectable in the tail of some strains by 10 d of age. Within the distal 2 mm of tail, end plates were not identified before 21 d of age. DNA yield (DNA weight/tissue weight) was greatest from the 5-mm biopsy harvest. Acute behavioral responses to biopsy varied by age and strain, and these differences were associated with vertebral maturation. Vertebral development progressed most rapidly in C57BL/6 mice, which also demonstrated the highest response rate to biopsy, whereas BALB/c mice had slower vertebral development and were less responsive. These findings support the collection of minimal lengths of tail tissue from mice at ages younger than 17 d, unless anesthesia or analgesia is provided.

The basics of animal biosafety and biocontainment training

The threat of biocontamination in an animal facility is best subdued by training. 'Training' is an ambiguous designation that may not be adequately appreciated in all animal facilities. The authors set down concrete training topics and provide practical advice on incorporating the basic principles of facility biosafety training--as well as the precautions and procedures that employees must know in case of accident or emergency--into various training models. They also discuss the current biosafety publications and guidelines and their relationship to biosafety training.

Gangrenous Clostridium perfringens infection and subsequent wound management in a rhesus macaque (Macaca mulatta)

A 10-y-old female rhesus macaque presented acutely with 3 large (diameter, greater than 4 cm), malodorous, ulcerogangrenous skin wounds on the left caudal thigh and calf. Limb radiographs revealed free gas infiltrating deep tissues, and histologic examination confirmed myonecrosis. Clostridium perfringens, Staphylococcus aureus, and Prevotella intermedia were isolated from the wounds. Antimicrobials, analgesics, and aggressive debridement of necrotic skin and muscle resulted in immediate clinical improvement of the primate. At 1 wk prior to presentation, the animal had received several intramuscular injections in close proximity to the site of infection. Repeated intramuscular injections through excrement-contaminated skin possibly contributed to the pathogenesis of infection. Continued therapy consisted of biweekly wound debridement and nonadherent bandage changes for 7 wk. The macaque regained full use of the affected leg and remains in good physical condition at our facility. Our management of this case led to improvements in training regarding intramuscular injection practices in our macaque colony. This case study is the first report of Clostridium perfringens myonecrosis in a laboratory nonhuman primate. We discuss various methodologies for the diagnosis and treatment of necrotizing clostridial infections.

Establishment of blood analyte intervals for laboratory mice and rats by use of a portable clinical analyzer

Portable clinical analyzers are currently used in human and veterinary medicine for diagnostic testing and blood monitoring; however, normal values for mice and rats of varying genetic backgrounds have not previously been reported. Blood was collected from unanesthetized mice (n = 131) and rats (n = 76) into lithium heparin tubes for analysis using E6+ cartridges for the portable analyzer. Results of glucose, blood urea nitrogen (BUN), sodium, potassium, chloride, hematocrit, and hemoglobin were compared to published ranges provided by a contract diagnostic laboratory. Analyzer ranges were computed as the mean +/- 2 standard deviations of the test samples, such that approximately 95% of tested animals would fall within the resultant range. The degree of overlap between analyzer and published ranges, or the percentage of the published range contained within the analyzer range, was calculated for all analytes. For mice, the ranges of 5 of 7 analytes had more than 57% overlap; for rats, ranges for 6 of 7 analytes had over 65% overlap. After the establishment of normal ranges, the analyzer was used to confirm hyperglycemia in Type I diabetic mice and elevated BUN in rats with induced glomerulosclerosis. The portable analyzer can be a valuable screening tool for both phenotyping and clinical care of rodents, with potential for investigations of both spontaneous and experimental disease in laboratory rodents.

Web searches for laboratory animal medicine: using the "mouse" for access to online resources

Laboratory animal medicine professionals must be able to integrate information from a variety of sources to make sound decisions. To address concerns from preveterinary and veterinary students that information about the specialty is difficult to locate, the authors examined the utility of electronic search engines to provide links to appropriate websites of significant educational value to the field. They assembled this reference document to assist veterinary students, residents, and postdoctoral fellows in the acquisition of online texts, journals, newsletters, government regulations, and other sources of current information as they relate specifically to laboratory animal medicine.

Envelope determinants for dual-receptor specificity in feline leukemia virus subgroup A and T variants

Gammaretroviruses, including the subgroups A, B, and C of feline leukemia virus (FeLV), use a multiple-membrane-spanning transport protein as a receptor. In some cases, such as FeLV-T, a nonclassical receptor that includes both a transport protein (Pit1) and a soluble cofactor (FeLIX) is required for entry. To define which regions confer specificity to classical versus nonclassical receptor pathways, we engineered mutations found in either FeLV-A/T or FeLV-T, individually and in combination, into the backbone of the transmissible form of the virus, FeLV-A. The receptor specificities of these viruses were tested by measuring infection and binding to cells expressing the FeLV-A receptor or the FeLV-T receptors. FeLV-A receptor specificity was maintained when changes at amino acid position 6, 7, or 8 of the mature envelope glycoprotein were introduced, although differences in infection efficiency were observed. When these N-terminal mutations were introduced together with a C-terminal 4-amino-acid insertion and an adjacent amino acid change, the resulting viruses acquired FeLV-T receptor specificity. Additionally, a W-->L change at amino acid position 378, although not required, enhanced infectivity for some viruses. Thus, we have found that determinants in the N and C termini of the envelope surface unit can direct entry via the nonclassical FeLV-T receptor pathway. The region that has been defined as the receptor binding domain of gammaretroviral envelope proteins determined entry via the FeLV-A receptor independently of the presence of the N- and C-terminal FeLV-T receptor determinants.

Lanolin as a treatment option for ringtail in transgenic rats

Ringtail is a condition characterized by dry skin and annular constrictions that sometimes result in loss of portions of the tail. This condition most commonly affects preweanling rats, and low relative humidity is thought to be a principal cause. The use of transgenic rats in our facility has been increasing since 2002, and we recently diagnosed several litters from transgenic Fischer 344 rats (Rattus norvegicus) with ringtail. Treatment was necessary to maintain the health and integrity of the tails to allow genotyping. Lanolin ointment was chosen because it is a nontoxic, inexpensive, effective moisturizer used for treating human skin conditions. We examined 5 litters comprising 37 pups total, ranging in age from 7 to 17 days at the time of presentation. Animals in 3 litters were randomly assigned to a treatment or nontreatment group, and all animals in the remaining 2 litters were treated. Lanolin was applied to the tails of treatment groups once daily for 6 d. Treatment was tolerated well by pups and no animals were rejected by the dams. After treatment, tail condition was scored from 0 to 3, with 0 representing a tail normal in appearance, and 3 representing severe disease. Chi square testing showed marginal statistical significance, with a trend for a higher percentage of treated rats having healthier tails on day 7 compared to untreated pups. The Pearson correlation between treatment and tail condition scores was significant. Results indicate that lanolin was an efficacious treatment option for ringtail.

Low-dose intraperitoneal Freund's adjuvant: toxicity and immunogenicity in mice using an immunogen targeting amyloid-beta peptide

Complete Freund's adjuvant (CFA) is effective for potentiating immune responses in mice when administered subcutaneously, and is often more potent when given intraperitoneally (i.p.). However, the the potential toxicity of i.p. administration in mice has led investigators and Institutional Animal Care and Use committees to increasingly view the use of CFA i.p. with reservation. We evaluated whether an 80% reduction in the dose of CFA administered i.p. to mice, compared to the i.p. doses used in a previous analysis, could abrogate the untoward effects associated with its use, while still maintaining adjuvanticity. Using a novel immunogen targeting the N-terminus of the 42-amino acid amyloid-beta peptide, we compared low dose CFA administered i.p., with three other commonly used adjuvants given i.p.: alum, incomplete Freunds adjuvant (IFA) and monophoshoryl lipid A + trehalose dicorynomycolate (MPL + TDM). The results of the study showed that, though the reduction in intraperitoneal dose of CFA mitigated transient weight loss and leukocytosis observed previously with higher doses of i.p. CFA, all mice administered CFA or IFA i.p. developed abdominal adhesions and granulomatous peritonitis. Mice from all adjuvant groups, however, appeared to tolerate the respective adjuvants well and excellent comparative immunogenicity was observed in mice immunized with the Freunds and MPL + TDM adjuvants. Consequently, we conclude that though a high-titered, humoral response may be generated using low dose CFA administered i.p., the accompanying toxicity remains significant, and thus alternative adjuvants and/or routes should be considered.

Use of low-dose chlorpromazine in conjunction with environmental enrichment to eliminate self-injurious behavior in a rhesus macaque (Macaca mulatta)

A 7-year-old, captive-bred, female rhesus macaque was placed in a quarantine facility upon arrival at our institution. At release from quarantine, she was observed pawing at and chewing on her left cheek. Physical examination revealed ulcerative lesions on the buccal surface of the left cheek. Initial differential diagnoses included Cercopithecine herpesvirus 1 (B virus)-induced lesions and bacterial infection. Dental abnormalities and cheek pouch foreign body were ruled out during the physical exam. Treatment with 30 mg/kg cefazolin intramuscularly every 12 h was initiated. Twelve days later, the animal presented with a 2 x 2-cm, full-thickness erosion involving the opposite (right) cheek. Treatment with buprenorphine (0.1 mg/kg intramuscularly every 24 h) was initiated. Cultures for B virus were negative, and only nonpathogenic bacteria were isolated from swabs of the lesions. Hematology and serum chemistry profiles were normal. A wedge biopsy of the lesion revealed no definitive etiology. Further observation revealed that the lesions likely resulted from self-injurious behavior (SIB). Treatment with low-dose chlorpromazine (1 mg/kg intramuscularly once daily for 25 days, and then 0.5 mg/kg intramuscularly once daily for 25 days) was initiated. Bodyweight and condition were maintained during therapy, and serial hematology and serum chemistry profiles were normal. The animal was moved into a different room, and a toy "necklace" was created. The SIB was eliminated, and lesions healed within 35 days. Presently, 20 months after presentation, this animal remains in good health.

Zoonoses of occupational health importance in contemporary laboratory animal research

In contemporary laboratory animal facilities, workplace exposure to zoonotic pathogens, agents transmitted to humans from vertebrate animals or their tissues, is an occupational hazard. The primary (e.g., macaques, pigs, dogs, rabbits, mice, and rats) and secondary species (e.g., sheep, goats, cats, ferrets, and pigeons) of animals commonly used in biomedical research, as classified by the American College of Laboratory Animal Medicine, are established or potential hosts for a large number of zoonotic agents. Diseases included in this review are principally those wherein a risk to biomedical facility personnel has been documented by published reports of human cases in laboratory animal research settings, or under reasonably similar circumstances. Diseases are listed alphabetically, and each section includes information about clinical disease, transmission, occurrence, and prevention in animal reservoir species and humans. Our goal is to provide a resource for veterinarians, health-care professionals, technical staff, and administrators that will assist in the design and on-going evaluation of institutional occupational health and safety programs.

Feline leukemia virus envelope sequences that affect T-cell tropism and syncytium formation are not part of known receptor-binding domains

The envelope protein is a primary pathogenic determinant for T-cell-tropic feline leukemia virus (FeLV) variants, the best studied of which is the immunodeficiency-inducing virus, 61C. We have previously demonstrated that T-cell-tropic, cytopathic, and syncytium-inducing viruses evolve in cats infected with a relatively avirulent, transmissible form of FeLV, 61E. The envelope gene of an 81T variant, which encoded scattered single-amino-acid changes throughout the envelope as well as a 4-amino-acid insertion in the C-terminal half of the surface unit (SU) of envelope, was sufficient to confer the T-cell-tropic, cytopathic phenotype (J. L. Rohn, M. S. Moser, S. R. Gwynn, D. N. Baldwin, and J. Overbaugh, J. Virol. 72:2686-2696, 1998). In the present study, we examined the role of the 4-amino-acid insertion in determining viral replication and tropism of FeLV-81T. The 4-amino-acid insertion was found to be functionally equivalent to a 6-amino-acid insertion at an identical location in the 61C variant. However, viruses expressing a chimeric 61E/81T SU, containing the insertion together with the N terminus of 61E SU, were found to be replication defective and were impaired in the processing of the envelope precursor into the functional SU and transmembrane (TM) proteins. In approximately 10% of cultured feline T cells (3201) transfected with the 61E/81T envelope chimeras and maintained over time, replication-competent tissue culture-adapted variants were isolated. Compensatory mutations in the SU of the tissue culture-adapted viruses were identified at positions 7 and 375, and each was shown to restore envelope protein processing when combined with the C-terminal 81T insertion. Unexpectedly, these viruses displayed different phenotypes in feline T cells: the virus with a change from glutamine to proline at position 7 acquired a T-cell-tropic, cytopathic phenotype, whereas the virus with a change from valine to leucine at position 375 had slower replication kinetics and caused no cytopathic effects. Given the differences in the replication properties of these viruses, it is noteworthy that the insertion as well as the two single-amino-acid changes all occur outside of predicted FeLV receptor-binding domains.