Dioxins are nearly ubiquitous environmental contaminants that are produced as byproducts during industrial processes, including the bleaching of paper and textiles. Contamination of animal bedding material with dioxins has been a concern for both laboratory and farm animals. The objective of this study was to determine whether the presence of cotton balls, provided to mice for enrichment, caused induction of the cytochrome P450 1A1 gene (Cyp1A1), which typically is stimulated through activation of the aryl hydrocarbon receptor (AhR) by dioxins and dioxin-like compounds. Cyp1A1 transcripts and protein in the liver were increased significantly by either exposure to cotton balls or treatment with a single dose of 2,3,7,8-tetrachlorodibenzo-para-dioxin. Unexposed controls displayed low levels of Cyp1A1 transcript and undetectable levels of CYP1A1 protein. These results suggest that cotton balls are potentially contaminated with dioxins and/or dioxin-like compounds that act as potent inducers of Cyp1a1 in laboratory animals if used as nesting material. This study underscores the necessity of considering dioxin content in products used for enrichment in animal facilities.

Excessive noise is well known to impair rodent health. To better understand the effect of construction noise and to establish effective noise limits during a planned expansion of our vivarium, we analyzed the effects of construction noise on mouse gestation and neonatal growth. Our hypothesis was that high levels of construction noise would reduce the number of live births and retard neonatal growth. Female Swiss Webster mice were individually implanted with 15 B6CBAF1/J embryos and then exposed to 70- and 90-dBA concrete saw cutting noise samples at defined time points during gestation. In addition, groups of mice with litters were exposed to noise at 70, 80, or 90 dBA for 1 h daily during the first week after parturition. Litter size, birth weight, incidence of stillborn pups, and rate of neonatal weight gain were analyzed. Noise decreased reproductive efficiency by decreasing live birth rates and increasing the number of stillborn pups.

Mite infestation of mice remains a persistent problem for many institutions, leading to numerous health problems and creating unknown and unwanted variables for research. In this study, mice with mite infestation demonstrated significantly higher levels of inflammatory cytokines, both at draining lymph nodes (axillary) and systemically, as compared with mice without mites. In addition, histologic evaluation revealed significant inflammation in mite-infested mice. Inflammatory changes were still present in the skin of mice at 6 to 8 wk after treatment, despite absence of detectable infestation at that time. Because these significant and lasting local and systemic changes have the potential to alter research findings, eradication of mites infestations should be an important goal for all institutions.

We determined the sensitivity of perianal tape impressions to detect Syphacia spp. in rats and mice. We evaluated 300 rat and 200 mouse perianal impressions over 9 wk. Pinworm-positive perianal tape impressions from animals with worm burdens at necropsy were considered as true positives. Conversely, pinworm-negative perianal tape impressions from animals with worm burdens were considered false negatives. The sensitivity of perianal tape impressions for detecting Syphacia muris infections in rats was 100%, and for detecting Syphacia obvelata in mice was 85.5%. Intermittent shedding of Syphacia obvelata ova is the most probable explanation for the decreased sensitivity rate we observed in mice. We urge caution in use of perianal tape impressions alone for Syphacia spp. screening in sentinel mice and rats.

Limited data are available on the pathogen status of contemporary rodent colonies in Taiwan. Here we summarized the rodent pathogen diagnostic records of the Taiwan National Laboratory Animal Center during a 4-y period that representing approximately 10% of the rodent colonies in Taiwan. Demand for pathogen diagnostic service increased continuously from 2004 to 2007, with a 20% increase each year. In 2007, more than 20% of the mouse colonies were positive for mouse parvovirus, mouse hepatitis virus, Theiler murine encephalomyelitis virus, and Mycoplasma pulmonis, with fewer colonies diagnosed as having infections of pneumonia virus of mice, mouse adenovirus, lymphocytic choriomeningitis virus, and reovirus. Almost 40% of tested rat colonies were positive for Mycoplasma pulmonis and rat parvovirus, with fewer colonies containing Kilham rat virus, sialodacryoadenitis virus, pneumonia virus of mice, Sendai virus, and Syphacia spp. These data provide a sound overall picture of the health status of mouse and rat colonies in Taiwan.

Protein electrophoresis is a common proven technique to determine the protein components of plasma or serum in human, veterinary, and laboratory animal medicine. Changes in albumin and globulin protein levels can provide early and valuable diagnostic and prognostic information. Here we describe a preliminary analysis of the distribution of serum protein fractions in adult BALB/c, C57BL/6, and CD1 mice and Sprague-Dawley rats and describe the changes in protein values from birth to maturity in BALB/c mice and Sprague-Dawley rats. Quantifiable changes in the electrophoretic profile were apparent in mice with chronic-active dermatitis.

The minipig is an increasingly popular species for use in behavioral and toxicologic studies. As a result, quantification of environmental enrichment preferences for this species is especially important. We exposed 6 individually housed prepubertal female Yucatan minipigs to 1 of 3 different objects on a rotating schedule: 2 sessions with a hard plastic ball (diameter, 21.0 cm), and 3 sessions each with a large plastic apple (diameter, 22.5 cm) and a soft rubber cone (height, 48.0 cm). Objects were changed every 4 to 5 d. The initial 15 min after each object change was recorded, and duration of object interaction and other behaviors (activity and interaction with the food bowl) were measured. Results indicated significantly longer interactions with the cone (mean ± SE, 282 ± 54 s) than the ball (14 ± 3 s). Interactions with the apple (66 ± 18 s) and ball did not differ significantly. Interactions with the apple decreased across the 3 sessions, whereas interaction with the cone remained high for most minipigs over the 3 sessions. Duration of activity appeared to be inversely correlated with duration of object interaction (that is, the longer the subject interacted with the object, the less it engaged in nonobject activity). These results provide valuable and practical information on the features of objects that minipigs appear to prefer and offer suggestions for future studies evaluating environmental enrichment paradigms with individually housed minipigs.

Nursery rearing is the single most important risk factor in the development of severe forms of abnormal behavior, such as self-biting, in rhesus macaques. This practice is common in research laboratories and typically involves continuous pair housing of infants without maternal contact. We examined the effects of variation in peer socialization on the behavioral development of rhesus infants by exposing 32 newborn infants to 4 different socialization routines: continuously paired; intermittently paired; continuously paired rotationally (partners rotated within the group once a week); and intermittently paired rotationally. Analyses revealed that infants paired intermittently exhibited 'floating limb' and self-biting behavior at significantly higher frequencies than those reared by using any other strategy. Results also suggested that continuous pairing was most effective in reducing the development of abnormal behaviors (that is, self-bite and floating limb), whereas intermittent pairing significantly reduced partner clinging and geckering. A principal component analysis revealed that floating limb behavior and self-biting are strongly associated. Self-biting began as early as 32 d of age, and a negative binomial regression on data of floating limb and self-biting revealed that early development of floating limb behavior predicts self-biting behavior later in development. Despite the significant effects of rearing strategies on the frequency of abnormal behaviors, we note that animals in all 4 treatment groups developed these traits to some degree. We suspect that the solitary incubator environment may be a trigger for the development of abnormal behaviors.

This study compares the use of traditional rectal thermometry with an implantable microchip temperature transponder in cats. The microchip transponder was implanted over the shoulder blades and was programmed with cat identification information. Concurrently, the cats were involved in a study in which they were infected experimentally with feline herpesvirus 1; this situation enabled temperature comparisons in both normal and abnormal ranges. Results from the microchip transponder technique were compared with rectal thermometry by using a concordance test of agreement. These data revealed close agreement between rectal and microchip transponder thermometry in the cat at both normal and abnormal temperature ranges.

Animal facilities generate a large amount of used bedding containing excrement as medical waste. We developed a recycling system for used bedding that involves soft hydrothermal processing. In this study, we examined the effects of bedding type on growth, hematologic and serum biochemical values, and organ weights of female and male mice reared on either recycled or fresh bedding from 3 to 33 wk of age. Neither growth nor physiology differed between mice housed on recycled bedding compared with fresh bedding. When 14-wk-old mice were bred, litter size and total number of weaned pups showed no significant differences between animals raised on recycled or fresh bedding. Because bedding type influences the environment within cages and animal rooms, we evaluated particulate and ammonia data from cages and animal rooms. Values were significantly lower from cages and rooms that used recycled bedding than from those using fresh bedding, thus indicating that recycled bedding has the potential to improve the environment within both cages and animal rooms. Overall, this study revealed that recycled bedding is an excellent material for use in housing laboratory rodents. Specifically, recycled bedding may reduce medical waste and maintain healthy environments within cages and animal rooms.

Here we describe 5 cases of molar malocclusions in adult pine voles (Microtus pinetorum) used for behavioral endocrinology studies. This species belongs to the subfamily Microtinae, which possess aradicular hypsodont molars. The abnormal molars identified caused apparent difficulty in mastication, resulting in poor body condition necessitating euthanasia. Postmortem examination of the oral cavity revealed grossly elongated mandibular and maxillary molars with abnormal wear at occlusal surfaces. This colony health problem was addressed successfully by adding autoclaved hardwood sticks to each cage as an enrichment tool.