From March through December 2010, the incidence of vaginal septa in our SPF breeding colony of BALB/cByJNarl mice was 14.2%. In general, septa obstructed half of the vaginal orifice. Here we sought to determine the effect of this defect by comparing the reproductive performance of affected (septate) mice with that of unaffected (nonseptate) mice. Our results showed that the rates of both copulatory plugs and pregnancy were significantly lower in septate mice than in nonseptate mice. Specifically, 23 of 45 bred septate female mice (51%) had vaginal plugs compared with 49 of 68 bred nonseptate females (72%). Only 12 septate female mice (27%) had successful pregnancies, compared with 37 nonseptate females (54%). Septate mice had a 1-logfold fewer intrauterine sperm after mating than did nonseptate mice. Three cases of dystocia were noted among septate mice whereas none occurred in nonseptate mice. Septate dams had a higher percentage of septate pups (15.5%) than did nonseptate dams (6.1%). Our findings indicate that vaginal septa affect the reproductive performance of laboratory mice and that such a defect should be considered as an exclusion criterion for the selection of future breeders in a mouse colony.

During pregnancy, women often show a willingness to make positive lifestyle changes, such as smoking cessation, initiation of a vitamin regimen, improvement of their diet, and increases in their levels of exercise or physical activity. To study health outcomes in both pregnant mice and their offspring, we developed a model of controlled maternal exercise during mouse pregnancy. Female ICR and C57BL/6 mice underwent controlled wheel walking for 1 h daily, 5 d each week, at a speed of 6 m/min prior to and during pregnancy and nursing. Dam body weight, food consumption, pregnancy rates, litter size, pup weights and litter survival were used as markers of pregnancy success and were not significantly affected by controlled maternal exercise. The proposed exercise paradigm is a safe pregnancy intervention and can be explored further.

Toxoplasmosis, a disease caused by the parasitic protozoan Toxoplasma gondii, can cause a number of clinical signs in mice, including weight loss. This weight loss likely is related to the host immune response and is important to monitor in Toxoplasma studies. Several studies have demonstrated that nesting material can affect body weights of mice. We therefore sought to assess the effects of nesting material on body weights of mice infected with Toxoplasma. We housed mice with or without nesting material and weighed and clinically assessed them twice weekly for 30 days prior to and 5 wk after Toxoplasma inoculation. Nesting material did not significantly alter the weights of mice after Toxoplasma inoculation but did decrease rates of growth prior to inoculation. Nesting material did not affect the clinical outcome of Toxoplasma infections, supporting the provision of nesting material in mouse Toxoplasma experiments.

This study addresses a recommendation in The Guide for the Care and Use of Laboratory Animals to provide singly housed nonhuman primates with intermittent access to large, enriched (play) caging. Research on the potential benefits of this type of caging is limited. The present study examines the effects of play caging on behavior, activity, and enrichment use. Singly housed, adult male, rhesus macaques (n = 10) underwent a baseline phase in their home cages, a 2-wk treatment phase with housing in play cages, and a posttreatment phase after returning to their home cages. Each subject underwent focal behavioral observations (n = 10; duration 30 min each) during each study phase, for a total of 150 h of data collection. Results showed increases in locomotion and enrichment use and a trend toward decreased abnormal behavior while subjects were in the play cage, with the durations of these behaviors returning to baseline levels after treatment. Anxiety-related behaviors decreased between the treatment and posttreatment phases but not between baseline and treatment, suggesting that outside factors may have influenced the decline. During the treatment phase, subjects spent more time in the upper quadrants of the play caging and preferred a mirror and forage boards as forms of enrichment. The greatest behavioral improvement occurred during the first week in the play cage. This study provides evidence to support the benefits of play caging for singly housed rhesus macaques.

Aspergillus fumigatus causes life-threatening pneumonia in immunocompromised patients. Conidia, the infectious form of the organism, are handled in a biologic safety cabinet under BSL2 conditions. However because germinated conidia form noninfectious hyphae in tissue, we hypothesized that rabbits inoculated intratracheally would grow A. fumigatus in their lungs but that the environment would remain free of this fungus, potentially permitting maintenance of infected animals under ABSL1 conditions. We performed a surveillance study for the presence of A. fumigatus in the environment before proceeding with antifungal therapy studies of experimental pulmonary aspergillosis. The expected outcome included absence of A. fumigatus in the environment, stool, and blood and presence in rabbit lungs. Female SPF New Zealand white rabbits were immunosuppressed and inoculated intratracheally (n = 4) or intraesophageally (n = 2) with 1.25 × 10⁸ conidia of A. fumigatus. Feces, pan liners, and walls were sampled daily during the 11-d experiment, and blood was sampled on days 2, 6, and 8 after inoculation. Samples were cultured on 5% Sabouraud glucose agar plates. Lungs were weighed and scored for hemorrhagic infarcts and homogenized for culture on 5% Sabouraud glucose agar and trypticase soy agar plates. Blood cultures, rabbit stool, and environmental swabs were all negative for A. fumigatus whereas the lungs inoculated intratracheally demonstrated 4.5 × 10² ± 0.8 × 10² CFU/g of A. fumigatus. Therefore, neutropenic rabbits with experimental invasive pulmonary aspergillosis do not shed conidia of A. fumigatus and can be safely housed under ABSL1 conditions after inoculation.

Trypanosoma cruzi, the causative agent of Chagas disease, is endemic in south Texas due to the abundant vector and wild small mammalian reservoir populations. This situation predisposes nonhuman primate colonies exposed to outdoor housing to infection from ingestion or bite of triatomid insects. Using a T. cruzi-specific real-time PCR and Trypanosome spp.-specific ELISA, we revealed a prevalence rate of 8.5% in a colony of outdoor-housed cynomolgus macaques. By using a discriminating kinetoplastid minicircle PCR, we eliminated the possibility of mixed prevalence with nonpathogenic trypanosomes and showed the ELISA results were specific for T. cruzi. In this study, we found an inverse relationship between antibody titers and circulating parasite load. Also, 23% of T. cruzi IgG ELISA-positive macaques were negative by real-time PCR. Furthermore, in a subset of infected macaques, cardiac tissue was infiltrated by inflammatory mononuclear cells and contained T. cruzi genomic and kinetoplast DNA despite lacking microscopic evidence of discrete parasite stages. In addition, 19% of the infected macaques had titers for cardiac troponin I autoantibody, which could contribute to autoimmune myocarditis or interfere with circulating troponin I measurements. These findings indicate the possibility of T. cruzi to interfere with the assessment of cardiac safety signals in preclinical toxicology and safety pharmacology studies and the necessity for prestudy screening for T. cruzi in outdoor-housed nonhuman primates from endemic areas.

We found that carprofen and meloxicam under 3 environmental conditions (ambient dark, ambient light, and 4 °C) remained stable for at least 7 d. We then evaluated the oral pharmacokinetics of meloxicam (20 mg/kg) and carprofen (10 mg/kg) in male C57BL/6 mice after oral gavage or administration in the drinking water. Mice did not drink meloxicam-medicated water but readily consumed carprofen-medicated water, consuming an average of 14.19 mL carprofen-medicated water per 100 g body weight daily; mice drank more during the dark phase than during the light phase. Plasma analyzed by HPLC (meloxicam) and tandem mass spectrometry (carprofen) revealed that the peak meloxicam and carprofen concentrations were 16.7 and 20.3 μg/mL and occurred at 4 and 2 h after oral gavage, respectively. Similar blood levels were achieved after 12 h access to the carprofen-medicated water bottle. At 24 h after oral gavage, the drugs were not detectable in plasma. Meloxicam plasma AUC, elimination half-life, apparent volume of distribution, and apparent oral clearance were 160.4 mg/L × h, 7.4 h, 0.36 L/kg, and 0.125 mL/h × kg, respectively. Carprofen plasma AUC, elimination half-life, apparent volume of distribution, and apparent oral clearance were 160.8 mg/L × h, 7.4 h, 0.42 L/kg, and 0.062 mL/h × kg, respectively. No gross or microscopic evidence of toxicity was seen in any mouse. Our findings indicate that carprofen can be administered in drinking water to mice and that medicated water bottles should be placed 12 to 24 h prior to painful procedures.

Cannulation of the common carotid artery for chronic, continuous radiotelemetric recording of aortic hemodynamic properties in mice is a highly invasive recovery surgery. Radiotelemetric recording, by its continuous nature, gives the most accurate measurements of hemodynamic variables in experimental animals, and is widely used in the study of cardiovascular diseases including hypertension. The American Heart Association has recommended data acquisition by radiotelemetric recording but did not provide guidelines regarding postoperative analgesic support. We assessed hemodynamic parameters, locomotor activity, food intake, and weight loss in radiotransmitter-implanted CD1 female mice receiving analgesic support during the first 48 h after surgery. The efficacy of analgesic support from the NSAID meloxicam was compared with that of the widely used opioid agonist buprenorphine and the related compound, tramadol. Meloxicam-treated mice recovered lost body weight more rapidly than did tramadol-or buprenorphine-treated mice. Furthermore, meloxicam-treated mice maintained circadian rhythm after surgery and had tighter regulation of mean arterial pressure than did tramadol- or buprenorphine-treated mice. Meloxicam was also superior with regard to food intake, locomotor activity, and limiting variance in hemodynamic parameters. This study indicates that when compared with buprenorphine and tramadol, meloxicam should be the postoperative analgesic of choice for radiotelemeter implantation in mice.

To compare the pharmacokinetics of coadministered intraperitoneal ketamine and xylazine in young (8 to 10 wk; n = 6) and old rats (2 to 2.4 y; n = 6), blood samples obtained at 15 and 30 min and 1, 2, and 4 h after drug administration were analyzed by HPLC–tandem mass spectrometry. In both groups, the withdrawal reflex was absent during anesthesia and was present at 1.1 (± 0.2) and 2.6 (± 0.7) h after drug administration in young and old rats, respectively, with the first voluntary movement at 1.5 ± 0.2 and 4.9 ± 1.0 h. Drug availability of ketamine and xylazine was 6.0 and 6.7 times greater, respectively, in old than young rats. The rate constant of elimination of both drugs was greatly decreased and the elimination half-life was significantly greater in old compared with young rats. In conclusion, age and associated factors affect the availability of ketamine and xylazine when coadministered to attain clinical anesthesia, changing the pharmacokinetics of these drugs and prolonging anesthesia duration and recovery times with aging. Compared with their young counterparts, aged rats required much higher doses to attain a similar level of anesthesia. Finally, the long half-life of both ketamine and xylazine, when coadministered to old rats, may be a factor in research protocols because residual plasma concentrations could still be present for as long as 3 and 5 d, respectively, after administration.

Despite the increasing use of rabbits as companion animals and models for biomedical research, rabbits have not been extensively studied to identify an efficacious postsurgical analgesic that does not cause systemic complications. The synergy of NSAID and systemic opioids is well-documented, and their combined use reduces the amount of either drug required for adequate analgesia. We measured fecal corticosterone metabolites (FCM) in rabbits after a minimally invasive vascular cut-down procedure. Rabbits received buprenorphine (0.03 mg/kg SC every 12 h for 3 d), meloxicam (0.2 mg/kg SC every 24 h for 3 d), buprenorphine–meloxicam (0.01 mg/kg–0.1 mg/kg SC every 24 h for 3 d), or a single dose of 0.5% bupivacaine (0.5 mL) infused locally at the incision site. By day 3 after surgery, buprenorphine, meloxicam, and bupivacaine groups showed elevated FCM levels, which continued to rise until day 7 and then gradually returned to baseline by day 28. In the buprenorphine–meloxicam group, FCM was relatively unchanged until day 3, when treatment was discontinued, and then began to rise. Rabbits in the buprenorphine–meloxicam group gained more weight over the 28-d study than did those in the other 3 treatment groups. This study shows that in rabbits low-dose buprenorphine administered with meloxicam effectively mitigates the FCM response that develops after surgery without the adverse effects associated with higher doses.

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.

Metastasis remains the most significant problem in the field of cancer. The biologic complexity that characterizes metastasis requires relevant in vivo models. When using murine models for pulmonary metastasis, longitudinal studies are valuable for following the progression of metastatic burden. Currently, the progression of pulmonary metastatic burden in experimental mice over time is monitored through advanced imaging approaches or the clinical assessment of morbidity. Because clinical signs of morbidity are often vague and unpredictable, an inexpensive and reproducible method to detect advanced metastatic burden—before the development of mortality—is needed. We have developed a noninvasive technique for assessing pulmonary metastatic burden in laboratory mice. The pulmonary assessment of advanced metastasis (PAAM) test is performed by restraining an awake mouse and gently applying pressure with the index finger under the xiphoid process. This pressure reduces the diaphragmatic component to respiration. Mice with advanced lung metastases show transient signs of respiratory distress within 3 s of the application of this pressure. Using PAAM in 4 distinct models (including sarcoma and mammary carcinoma histologies) of experimental (tail vein) pulmonary metastasis (n = 114 mice), among 3 independent evaluators yielded 94% positive and negative predictive values, which were validated by histologic assessment of postmortem lung tissue. PAAM is a simple, reproducible, and efficient method to assist in the detection of advanced pulmonary metastasis in mice and contributes to their humane care during longitudinal studies.

NSAID administration is often chosen as a method of minimizing pain and discomfort for nonhuman primates. Of concern when using NSAID is the potential for decreased platelet aggregation due to the inhibition of cyclooxygenases 1 and 2. In both dogs and humans, the use of NSAID that are selective for cyclooxygenase 2, like meloxicam, minimizes the inhibition of platelet aggregation in comparison to nonselective NSAID, like aspirin, that inhibit both isoforms of cyclooxygenase. In this study, we measured platelet aggregation in rhesus macaques (n = 6) by using the impedance method on a multiple-electrode aggregometer at baseline, at 1 and 4 d after initiating treatment with aspirin or meloxicam, and after a washout period. There was no statistical difference between aggregation at baseline and after 1 or 4 d of meloxicam treatment, but platelet aggregation decreased after both 1 and 4 d of aspirin therapy. Our data suggest that clinically significant postoperative hemorrhage is unlikely in rhesus macaques briefly treated with meloxicam.