This study measured blood parameters, particularly those related to coagulation, and alterations in the expression levels of blood-coagulation–related genes in lactating Sprague–Dawley rats. The day of delivery was designated as lactation day 0 (LD 0). On the day after delivery (LD 1), prothrombin time and overall activity of vitamin-K–dependent coagulation factors were decreased, whereas fibrinogen contents, platelet counts and antithrombin III concentrations were increased as compared with those in nonpregnant rats. In addition, hepatic expression of blood-coagulation–related genes in the liver was increased at LD 0 as compared with that in nonpregnant rats. These changes may be physiologic responses to prevent prolonged bleeding at delivery. Except for fibrinogen content, which remained elevated, the described changes returned to baseline on and after LD 7. Activities of AST, ALT, and ALP were increased on LD 7, 14, and 21 as compared with nonpregnant rats. In contrast, total protein, albumin, Cl, and Ca were consistently lower on LD 7, 14, or 21 as compared with levels in nonpregnant rats. These results provide background data for evaluation of nursing rats.

We obtained whole-blood hematologic and serum biochemical values from 38 captive-bred cotton-top tamarins (Saguinus oedipus). Data were analyzed to determine the effect of sex on blood parameters. Significant differences between either the means or medians of male and female tamarins were found for creatinine, hematocrit, hemoglobin, RBC count, and PCV. These results establish baseline hematologic and serum biochemical values and provide a useful resource not previously available in the peer-reviewed literature for the clinical care of cotton-top tamarins, a critically endangered New World primate, in a captive setting.

Disposable individually ventilated cages have lids that restrict air exchange when the cage is not mechanically ventilated. This design feature may cause intracage CO₂ to increase and O₂ to decrease (hypercapnic and hypoxic conditions, respectively) when the electrical supply to the ventilated rack fails, the ventilated rack malfunctions, cages are docked in the rack incorrectly, or cages are removed from the ventilated rack for extended periods of time. We investigated how quickly hypercapnic and hypoxic conditions developed within disposable individually ventilated cages after removal from mechanical ventilation and compared the data with nondisposable static cages, disposable static cages, and unventilated nondisposable individually ventilated cages. When disposable individually ventilated cages with 5 adult mice per cage were removed from mechanical ventilation, CO₂ concentrations increased from less than 1% at 0 h to approximately 5% at 3 h and O₂ levels dropped from more than 20% at 0 h to 11.7% at 6 h. The breathing pattern of the mice showed a prominent abdominal component (hyperventilation). Changes were similar for 4 adult mice per cage, reaching at least 5% CO₂ at 4 h and 13.0% O₂ at 6 h. For 3 or 2 mice per cage, values were 4.6% CO₂ and 14.7% O₂ and 3.04% CO₂ and 17.1% O₂, respectively, at 6 h. These results document that within disposable individually ventilated cages, a hypercapnic and hypoxic microenvironment develops within hours in the absence of mechanical ventilation.

The goal of this swas to evaluate the effectiveness of a new proprietary processed corncob bedding material (PCC) compared with standard corncob in ventilated and static mouse housing systems. Intracage ammonia levels, bacterial growth, and absorptive capacity of bedding were measured for cages of C57BL/6 mice under nonautoclaved and autoclaved conditions on static and ventilated racks in a barrier facility. Ammonia concentration was measured daily, and cages were removed from the study when measurements reached or exceeded 25 ppm. Bacterial growth in bedding was quantified and speciated before exposure to mice and at the time of cage removal. The absorptive capacity of all bedding material was determined under autoclaved and nonautoclaved conditions. Ventilated cages with PCC or autoclaved corncob took longer to reach ammonia concentrations of 25 ppm than did those with corncob or autoclaved PCC; PCC-filled cages remained below 25 ppm NH₃ for at least 3 wk. The type of bedding material did not affect the number of days required to reach 25 ppm in static cages. Compared with other bedding types in the absence of mice, 1/4-in. PCC had a lower and 1/8-in. corncob a higher bacterial load. Autoclaving altered the absorptive capacity of 1/4-in. bedding materials, and for 1/8-in. bedding, corncob was more absorptive than PCC regardless of autoclaving. The results of this study indicate that PCC is comparable to autoclaved corncob in controlling intracage ammonia levels, and a cage-change interval of 3 wk is possible when ventilated cages are used with this bedding.

Many sources of variation in animal experiments are related to characteristics of the animal or its husbandry conditions. In ethologic studies, observational methods can also affect interexperimental variation. Different descriptions for a behavior can lead to divergent findings that may be incorrectly attributed to other factors if not recognized as stemming from a classification dissonance. Here we discuss 2 observational studies in Mongolian gerbils (Meriones unguiculatus). The first study describes how data vary when 2 different working definitions are used for stereotypic digging: WD_mor, a definition based on a morphologic description of the behavior, and WD₁₂, a definition that relies mainly on a duration criterion of digging bouts (greater than 12 s). The total duration and number of stereotypic bouts were 22.0% and 63.1% lower, respectively, when WD₁₂ was applied compared with WD_mor. However, strong correlations existed between data generated by WD_mor and WD₁₂, indicating that the 2 definitions yielded qualitatively similar results. The second study provides the first report that laboratory gerbils develop stereotypic behavior that is characterized by alternating bouts of digging and bar-gnawing. Of the 1685 stereotypy bouts investigated, 9.1% comprised both stereotypies, 87.6% consisted of digging only, and 3.3% consisted of bar gnawing only. Working definitions that neglect combined stereotypies can result in considerable underestimation of stereotypic behavior in Mongolian gerbils.

We performed the initial assessment of an alternative pressurized intraventilated (PIV) caging system for laboratory mice that uses direct-current microfans to achieve cage pressurization and ventilation. Twenty-nine pairs of female SPF BALB/c mice were used, with 19 experimental pairs kept in PIV cages and 10 control pairs kept in regular filter-top (FT) cages. Both groups were housed in a standard housing room with a conventional atmospheric control system. For both systems, intracage temperatures were in equilibrium with ambient room temperature. PIV cages showed a significant difference in pressure between days 1 and 8. Air speed (and consequently airflow rate) and the number of air changes hourly in the PIV cages showed decreasing trends. In both systems, ammonia concentrations increased with time, with significant differences between groups starting on day 1. Overall, the data revealed that intracage pressurization and ventilation by using microfans is a simple, reli- able system, with low cost, maintenance requirements, and incidence of failures. Further experiments are needed to determine the potential influence of this system on the reproductive performance and pulmonary integrity in mice.

The personal protective equipment (PPE) required for entry into rodent barrier rooms often includes a hair bonnet, face mask, disposable gown, gloves, and shoe covers. Traditionally, shoe covers have been considered essential PPE for maintaining a 'clean' animal room. The introduction of microisolation caging and ventilated rack housing prompted us to reevaluate the contribution of shoe covers to bioexclusion. Contamination powder that fluoresces under black light was to track particle dispersal on the floor and personnel. The test mouse room contained a ventilated microisolation rack and biosafety cabinet. Powder was applied directly inside or outside the animal room doorway. PPE with or without shoe covers was donned outside of the animal room doorway and discarded on exiting. Participants either were scanned on entry into the room for the presence of florescence or asked to complete a simulated standard animal room activity while wearing full PPE. Animal rooms were scanned for florescence after exit of participants. All participants donning shoe covers fluoresced in multiple areas, primarily on gloves and gowns. Shoe covers had no effect on the spread of powder in normal traffic patterns, with no powder detected within caging. Powder also was used to determine the distance substances could be carried on the floor from building entry points. Results indicate that shoe covers do not improve (and actually may compromise) bioexclusion. Donning of shoe covers offers a potential for contamination of personnel from contact with shoe bottoms.

Corynebacterium bovis is a common pathogen in athymic nude mouse colonies. Control and eradication of the organism are challenging because depopulation and restricted colony access are often not options within vivaria. We evaluated potential sources and dissemination routes of C. bovis in an enzootically infected colony. Immunocompetent mice and personnel were evaluated for their potential to carry C. bovis, and husbandry and sanitation methods were evaluated for their efficacy in preventing cross-contamination. C. bovis was detected in furred immunocompetent mice previously exposed to infected athymic nude mice and in the nasopharynx of humans. Microisolation cages were not effective in maintaining athymic nude mice C. bovis-free when they were housed in a room known to contain immunodeficient mice with C. bovis infections. A tunnel washer that provided a ≥180 °F final rinse provided effective elimination of C. bovis from cage components. Passive and active air sampling techniques showed airborne dispersal of C. bovis despite the use of individually ventilated caging systems and stringent operational standards. Bacterial growth was not observed in settle plates placed inside autoclaved individually ventilated microisolation cages on various ventilated racks for 24-h periods. C. bovis aerosolization was shown to be a means of spread of the bacterium during cage-change procedures inside a class II type A2 biosafety cabinet. Our findings indicate that C. bovis can be a pervasive environmental contaminant in infected rodent holding rooms and successful eradication strategies must include environmental decontamination and attention to air quality.

Mites of 3 genera—Myobia, Myocoptes, and Radfordia —continue to plague laboratory mouse facilities, even with use of stringent biosecurity measures. Mites often spread before diagnosis, predominantly because of detection difficulty. Current detection methods have suboptimal sensitivity, are time-consuming, and are costly. A sensitive serodiagnostic technique would facilitate detection and ease workload. We evaluated whether total IgE increases could serve as a serodiagnostic marker to identify mite infestations. Variables affecting total IgE levels including infestation duration, sex, age, mite species, soiled-bedding exposure, and ivermectin treatment were investigated in Swiss Webster mice. Strain- and pinworm-associated effects were examined by using C57BL/6 mice and Swiss Webster mice dually infested with Syphacia obvelata and Aspiculuris tetraptera, respectively. Mite infestations led to significant increases in IgE levels within 2 to 4 wk. Total IgE threshold levels and corresponding sensitivity and specificity values were determined along the continuum of a receiver-operating characteristic curve. A threshold of 81 ng/mL was chosen for Swiss Webster mice; values above this point should trigger screening by a secondary, more specific method. Sex-associated differences were not significant. Age, strain, and infecting parasite caused variability in IgE responses. Mice exposed to soiled bedding showed a delayed yet significant increase in total IgE. Treatment with ivermectin reduced total IgE levels within 2 wk. Our data suggest that increases in total IgE in Swiss Webster and C57BL/6 mice warrant investigation, especially because mite infestations can rapidly elevate total IgE levels. We propose that using total IgE levels routinely in serologic panels will enhance biosecurity.

Laboratory mice typically are anesthetized by either inhalation of volatile anesthetics or injection of drugs. Here we compared the acute and postanesthetic effects of combining both methods with standard inhalant monoanesthesia using sevoflurane in mice. After injection of fentanyl–midazolam or S-ketamine as premedication, a standard 50-min anesthesia was conducted by using sevoflurane. Addition of fentanyl–midazolam (0.04 mg/kg–4 mg/kg) induced sedation, attenuation of aversive behaviors at induction, shortening of the induction phase, and reduced the sevoflurane concentration required by one third (3.3% compared with 5%), compared with S-ketamine (30 mg/kg) premedication or sevoflurane alone. During anesthesia, heart rate and core body temperature were depressed significantly by both premedications but in general remained within normal ranges. In contrast, with or without premedication, substantial respiratory depression was evident, with a marked decline in respiratory rate accompanied by hypoxia, hypercapnia, and acidosis. Arrhythmia, apnea, and occasionally death occurred under S-ketamine–sevoflurane. Postanesthetic telemetric measurements showed unchanged locomotor activity but elevated heart rate and core body temperature at 12 h; these changes were most prominent during sevoflurane monoanesthesia and least pronounced or absent during fentanyl–midazolam–sevoflurane. In conclusion, combining injectable and inhalant anesthetics in mice can be advantageous compared with inhalation monoanesthesia at induction and postanesthetically. However, adverse physiologic side effects during anesthesia can be exacerbated by premedications, requiring careful selection of drugs and dosages.

The oral route is the most frequently used method of drug intake in humans. Oral administration of drugs to laboratory animals such as mice typically is achieved through gavage, in which a feeding needle is introduced into the esophagus and the drug is delivered directly into the stomach. This method requires technical skill, is stressful for animals, and introduces risk of injury, pain and morbidity. Here we investigated another method of drug administration. The benzimidazole derivative albendazole was emulsified in commercially available honey and administered to mice by voluntary feeding or gavage. Mice that received albendazole by either gavage or honey ingestion had virtually identical levels of serum albendazole sulfoxide, indicating that uptake and metabolism of albendazole was similar for both administration techniques. In addition, dosing mice with the albendazole–honey mixture for 8 wk had antiparasitic activity comparable to earlier studies using gavage for drug administration. Compared with gavage, voluntary ingestion of a drug in honey is more rapid, less stressful to the animal, and less technically demanding for the administrator. Because of its low cost and ready availability, honey presents a viable vehicle for drug delivery.

Pinworm infection (oxyuriasis) is a common problem in rodent colonies. Facility-wide prophylactic treatment of all mice with a diet containing therapeutic levels of fenbendazole for several weeks is often used to control pinworm outbreaks. We examined the effect of feeding a therapeutic diet containing 150 ppm fenbendazole on the growth of EMT6 mouse mammary tumors implanted into BALB/c Rw mice. Mice were randomized to receive either a fenbendazole-containing or control diet for 1 wk before tumor cells were injected intradermally in the flanks and throughout tumor growth. Tumor growth was monitored by serial measurements of tumor diameters from the time tumors became palpable until they reached 1000 mm³. The medicated diet did not alter tumor growth, invasion, or metastasis. When tumors reached volumes of approximately 100 mm³, some were irradiated locally with 10 Gy of X-rays. Irradiation significantly delayed tumor growth; fenbendazole did not alter the radiation-induced growth delay. However, cell culture studies showed that fenbendazole concentrations not far above those expected in the tissues of mice on this diet altered the growth of the tumor cells in culture. Recent data from other laboratories also have demonstrated effects of fenbendazole that could complicate experiments. Care should therefore be exercised in deciding whether chow containing fenbendazole should be administered to mouse colonies being used in cancer research.

Here we evaluated the ability of a new, dual blood-pressure telemetry transmitter to simultaneously measure pulmonary and systemic blood pressure and the electrocardiogram in rats. The transmitter was implanted in normotensive and monocrotaline-induced pulmonary hypertensive Wistar rats, with sensing catheters placed in the pulmonary artery (channel 1) and descending aorta (channel 2). Biopotential electrodes were positioned to record an apex-based lead II electrocardiogram. Pulmonary and systemic arterial blood pressure and electrocardiographic waveforms were recorded between 2 and 12 wk after implantation of the transmitter. During this period, pulmonary arterial pressure progressively increased in monocrotaline-treated compared with saline-treated rats. The pharmacologic response of rats to reference compounds was measured by using the transmitter to validate the technique and to evaluate the ability of the device to transmit changes in blood pressure and the electrocardiogram. Validation against 2 Millar high-fidelity blood-pressure catheters confirmed the accuracy of the blood pressure data recorded with the transmitter. In addition, local tolerance of the associated catheters was confirmed by histologic examination.

Cotton rats (Sigmodon hispidus) are a valuable animal model for many human viral diseases, including polio virus, measles virus, respiratory syncytial virus, and herpes simplex virus. Although cotton rats have been used in research since 1939, few publications address handling and sampling techniques for this species, and the retroorbital sinus remains the recommended blood sampling site. Here we assessed blood sampling methods that are currently used in other species and a novel subzygomatic sampling site for their use in S. hispidus. The subzygomatic approach accesses a venous sinus that possibly is unique to this species and that lies just below the zygomatic arch of the maxilla and deep to the masseter muscle. We report that both the novel subzygomatic approach and the sublingual vein method can be used effectively in cotton rats.

This study used positron emission tomography–computed tomography (PET–CT) to evaluate the effects of 4 anesthetic protocols on 2-deoxy-2-[ ¹⁸ F]-fluoro-D-glucose ( ¹⁸ F-FDG) accumulation in the brains and hearts of miniature pigs (Sus scrofa domestica). The ¹⁸ F-FDG standard uptake value was quantified by dividing the brain into 6 regions: cerebellum, brainstem, and frontal, parietal, temporal, and occipital lobes. Five (2 female and 3 male) clinically normal miniature pigs were premedicated with medetomidine (200 μg/kg IM) after which the following 4 anesthetic protocols were administered by using a crossover design: 1) propofol (4 mg/kg IV)–isoflurane inhalation; 2) propofol (4 mg/kg IV); 3) ketamine (5 mg/kg IV); 4) tiletamine–zolazepam (4.4 mg/kg IM). Compared with levels after other protocols, brain accumulation of ¹⁸ F-FDG increased during propofol anesthesia but decreased with tiletamine–zolazepam. Relative to that due to other protocols, heart accumulation of ¹⁸F-FDG increased with propofol–isoflurane anesthesia but decreased with tiletamine–zolazepam. Comparing glucose accumulation in the brain and heart of miniature pigs by using PET–CT, we found that glucose accumulation varied according to the anesthetic protocol and between the 2 organs. These results can be used to evaluate how different anesthetic agents affect glucose metabolism in brain and heart of miniature pigs. Furthermore, these data should be considered when selecting an anesthetic agent for miniature pigs that will undergo PET–CT imaging with ¹⁸ F-FDG.

In Spring 2008, 175 adult female Xenopus laevis were exposed to construction-related vibrations that caused overt water rippling in the frog tanks. The 3 affected tanks were custom-built static, 300-gal 'pond-style' tanks that sat on the floor of the housing room. The water in the tank developed visible ripples as a result of the vibrations transmitted through the floor during jack-hammering in an adjacent room that was approximately 10 ftaway. All frogs in the tanks displayed buoyancy problems, excessive air gulping, and skin sloughing; ultimately 7 frogs died. In addition, these 7 animals were bloated, and 5 of these 7 had regurgitated and everted their stomach and distal esophagus into the oral cavity, resulting in airway obstruction and death. Gross pathologic findings included regurgitation and eversion of the stomach of the distal portion of the esophagus into the oral cavity, obstruction of the airway, and lung overinflation. No significant histologic lesions were observed. Construction vibrations transmitted through the water appeared to have disrupted the mechanoreceptive function of the lateral line system, resulting in overstimulation of the noxious feeding response, regurgitation, and eversion of the stomach and distal esophagus into the oral cavity and subsequent suffocation due to airway obstruction. After immediate cessation of the jack-hammering and relocation of the remaining frogs, no additional morbidities or mortalities occurred.