Environmental enrichment is the provision of different substrates to mimic an animal’s natural environment and encourage natural, species-specific behavior. However, the use of enrichment to improve breeding efficiency in mouse models for neurologic conditions is not well described. There are reports that diminished environmental stimuli and chronic isolation can result in the early expression of the Parkinson phenotype in mice with a genetic predisposition to the disease. In this study, we compared the provision of crinkle paper, DietGel, and their combination on reproductive parameters in B6.Cg-Tg(THY1-SNCA*A53T)M53Sud mice. We found that enhanced enrichment combined with enhanced nutrition increased dam weight and decreased the interlitter intervals. In addition, enhanced enrichment increased the production index, number of pups born, pups weaned, and the percent survival of pups. This study underscores the importance of incorporating enrichment to enhance the reproductive parameters in mice that are models of Parkinson disease.

Seasonal infection rates of individual viruses are influenced by synergistic or inhibitory interactions between coincident viruses. Endemic patterns of SARS-CoV-2 and influenza infection overlap seasonally in the Northern hemisphere and may be similarly influenced. We explored the immunopathologic basis of SARS-CoV-2 and influenza A (H1N1pdm09) interactions in Syrian hamsters. H1N1 given 48 h prior to SARS-CoV-2 profoundly mitigated weight loss and lung pathology compared to SARS-CoV-2 infection alone. This was accompanied by the normalization of granulocyte dynamics and accelerated antigen-presenting populations in bronchoalveolar lavage and blood. Using nasal transcriptomics, we identified a rapid upregulation of innate and antiviral pathways induced by H1N1 by the time of SARS-CoV-2 inoculation in 48 h dual-infected animals. The animals that were infected with both viruses also showed a notable and temporary downregulation of mitochondrial and viral replication pathways. Quantitative RT-PCR confirmed a decrease in the SARS-CoV-2 viral load and lower cytokine levels in the lungs of animals infected with both viruses throughout the course of the disease. Our data confirm that H1N1 infection induces rapid and transient gene expression that is associated with the mitigation of SARS-CoV-2 pulmonary disease. These protective responses are likely to begin in the upper respiratory tract shortly after infection. On a population level, interaction between these two viruses may influence their relative seasonal infection rates.

Perinatal mortality is a common problem in mouse breeding colonies. Few studies have examined the influence of environmental changes on mouse pup survival. In this study, monogamous breeding cages of C57BL/6J mice were set up and randomized into 3 cage change groups: 1) cage change at 8 d after parturition, 2) cage change at 3 d after parturition, or 3) cage change at 3 d after parturition with the addition of a polycarbonate hut in the cage. Pairs were bred to produce a minimum of 4 litters. Pup survival to weaning relative to experimental cage change date, and survival rates after cage change were evaluated. The results revealed no significant differences between experimental groups. The majority of pup loss occurred within the first 24 h after birth for those pups that were alive at birth. Overall, the postpartum day of cage change did not affect the perinatal survival of mouse pups.

Maintaining compliance with cage density recommendations in The Guide for the Care and Use of Laboratory Animals precludes continuous trio breeding in standard-sized mouse cages. This study evaluated and compared several parameters of reproductive performance, intracage ammonia concentration, and fecal corticosterone levels in 2 strains of mice, C57BL/6J (B6) and B6.129S(Cg)-Stat1tm1Dlv/J (STAT1-/-), housed as continuous breeding pairs or trios in standard-sized mouse cages, and continuous breeding trios in standard-sized rat cages. Reproductive performance data indicated that STAT1-/- trios raised in rat cages weaned significantly more pups per litter than did STAT1-/- trios raised in mouse cages, and B6 mice had higher pup survival rates at weaning than did STAT1-/- mice in mouse cages housing continuous breeding trios. In addition, the Production Index was significantly higher for B6 breeding trios in rat cages than for B6 trios in mouse cages. Intracage ammonia concentration increased with cage density, with significantly higher ammonia concentrations in mouse cages housing trios compared with rat cages housing trios. However, fecal corticosterone levels did not differ significantly regardless of genotype, breeding configuration, or cage size, and daily health checks revealed no clinical abnormalities under any of the conditions evaluated. These results suggest that, although continuous trio breeding in standard-sized mouse cages does not seem to compromise mouse welfare, it offers no advantage in reproductive performance compared with pair breeding, and in some cases, it might be disadvantageous in this regard. Further, high intracage ammonia in mouse cages containing breeding trios might necessitate more frequent cage changes.

Human activities have caused massive losses of natural populations across the globe. Like many groups, amphibians have experienced substantial declines worldwide, driven by environmental changes such as habitat conversion, pollution, and disease emergence. Each of these drivers is often found in close association with the presence of roads. Here we report a novel consequence of roads affecting an amphibian native to much of North America, the wood frog (Rana sylvatica). Across 38 populations distributed from southern to central New England, we found that adult wood frogs living adjacent to roads had higher incidence and severity of oedema (indicated by obvious bloating caused by subcutaneous fluid accumulation) during the breeding season than frogs living away from the influence of roads. This effect was best explained by increased conductivity of breeding ponds, probably caused by runoff pollution from road salt used for de-icing. Oedema severity was negatively correlated with locomotor performance in more northerly populations. Interestingly, northern populations experience more intense winters, which tends to result in more de-icing salt runoff and increased energetic demands associated with overwintering cryoprotection needs. Thus, this emerging consequence of roads appears to impose potential fitness costs associated with locomotion, and these effects might be most impactful on populations living in regions where de-icing is most intense. Together, our findings reveal a novel set of impacts of roads and runoff pollution on wood frog physiology and performance, which seem likely to contribute to population decline. Given the global prevalence of roads and increasing salinisation of freshwater habitats, oedema and related impacts could be widespread consequences faced by amphibian populations across much of the planet's temperate zones.

Human activities have caused massive losses of natural populations across the globe. Like many groups, amphibians have experienced substantial declines worldwide, driven by environmental changes such as habitat conversion, pollution, and disease emergence. Each of these drivers is often found in close association with the presence of roads. Here we report a novel consequence of roads affecting an amphibian native to much of North America, the wood frog ( Rana sylvatica ). Across 38 populations distributed from southern to central New England, we found that adult wood frogs living adjacent to roads had higher incidence and severity of edema (bloating caused by fluid accumulation) during the breeding season than frogs living away from the influence of roads. This effect was best explained by increased conductivity of breeding ponds, caused by runoff pollution from road salt used for de-icing. Edema severity was negatively correlated with locomotor performance in more northerly populations. Interestingly, northern populations experience more intense winters, which tends to result in more de-icing salt runoff and increased energetic demands associated with overwintering cryoprotection needs. Thus, this emerging consequence of roads appears to impose potential fitness costs associated with locomotion, and these effects might be most impactful on populations living in regions where de-icing is most intense.

Immunodeficient rats are valuable in transplantation studies, but are vulnerable to infection from opportunistic organisms such as fungi. Immunodeficient Rag1- and Il2rg-deficient (RRG) rats housed at our institution presented with dark, proliferative, keratinized dermal growths. Histologic and PCR results indicated that the predominant organism associated with these lesions was fungus from the family Mucoraceae, mostly of the genus Rhizopus. The Mucoraceae family of fungi are environmental saprophytes and are often found in rodent bedding. These fungi can cause invasive opportunistic infections in immunosuppressed humans and animals. We discuss husbandry practices for immunosuppressed rodents with a focus on controlling fungal contaminants.

Studies using the Mouse Grimace Scale have shown that for many NSAID, including meloxicam, minimal doses of at least 20 mg/kg may be necessary to achieve adequate peri- and postoperative analgesia in mice. However, more data are needed to determine whether such NSAID doses exceed the threshold for gastrointestinal ulceration or induce other relevant pathology. We administered equal volumes of saline or injectable meloxicam (1 or 5 mg/mL) at a dose of 20 mg/kg SC to 20 young adult male and female C57BL/6N mice daily for 6 d and performed necropsies on all mice on the seventh day. Mice given 5 mg/mLmeloxicam subcutaneously developed significantly more severe pathology at the injection site than saline controls. Pathologywas characterized by full-thickness epidermal necrosis; cavitary lesions within subcutis, muscle, or fat; steatitis; and myositis.Mice that received 1 mg/mL meloxicam subcutaneously developed lesions that were qualitatively similar but far less severe than those after 5 mg/mL. However, no pathologic lesions typically associated with NSAID toxicity, such as gastric ulceration and liver and kidney lesions, were seen. These results demonstrate that although meloxicam injected subcutaneously causes concentration-dependent skin pathology at the injection site, a dose of 20 mg/kg can be safely administered subcutaneously at a concentration of 1 mg/mL for as long as 6 d.

Environmental factors contribute to Type 1 diabetes (T1D) susceptibility. The gut microbiome, which includes bacteria, viruses, and fungi, contributes to this environmental influence, and can induce immunological changes. The gut viral component of the microbiome, related to T1D has mostly focused on coxsackieviruses and rotavirus. The role of norovirus, another common enteric virus, in susceptibility to T1D was hitherto unknown. Norovirus is highly infectious and encountered by many children. We studied the mouse norovirus 4 (MNV4), related to human noroviruses, in the Non-obese diabetic (NOD) mouse model, to determine its role in influencing susceptibility to T1D. We infected MNV-free NOD mice with MNV4 by exposing the mice to MNV4-positive bedding from an endemically-infected mouse colony to mimic a natural infection. Control MNV-free NOD mice were exposed to MNV-free bedding from the same colony. Interestingly, MNV4 infection protected NOD mice from the development of T1D and was associated with an expansion of Tregs and reduced proinflammatory T cells. We also found MNV4 significantly modified the gut commensal bacteria composition, promoting increased α-diversity and Firmicutes/Bacteroidetes ratio. To elucidate whether T1D protection was directly related to MNV4, or indirectly through modulating gut microbiota, we colonized germ-free (GF) NOD mice with the MNV4-containing or non-MNV4-containing viral filtrate, isolated from filtered fecal material. We found that MNV4 induced significant changes in mucosal immunity, including altered Tuft cell markers, cytokine secretion, antiviral immune signaling markers, and the concentration of mucosal antibodies. Systemically, MNV4-infection altered the immune cells including B cell subsets, macrophages and T cells, and especially induced an increase in Treg number and function. Furthermore, in vitro primary exposure of the norovirus filtrate to naïve splenocytes identified significant increases in the proportion of activated and CTLA4-expressing Tregs. Our data provide novel knowledge that norovirus can protect NOD mice from T1D development by inducing the expansion of Tregs and reducing inflammatory T cells. Our study also highlights the importance of distinguishing the mucosal immunity mediated by bacteria from that by enteric viruses.

Gray short-tailed opossums are used in a wide variety of research in the areas of developmental biology, oncology, immunology, and comparative biology. Despite many frequent experimental manipulations of these animals under anesthesia, few studies to date have characterized the effects of anesthesia in this species. Our aim was to identify safe and effective injectable anesthetic combinations using ketamine and xylazine or ketamine and dexmedetomidine at doses of 40 mg/kg to 100 mg/kg for ketamine, 5 mg/kg to 10 mg/kg for xylazine, and 0.05 mg/kg to 0.1 mg/kg for dexmedetomidine. Effects of the proposed regimens ranged from light sedation to surgical anesthesia, but only 100 mg/kg ketamine + 0.1 mg/kg dexmedetomidine induced surgical anesthesia in all opossums, with a mean duration of 25.4 min. The 2 lowest doses of ketamine and xylazine (40 mg/kg ketamine + 5 mg/kg xylazine and 40 mg/kg ketamine + 10 mg/kg xylazine) achieved sedation to light anesthesia in all animals but did not produce a surgical plane of anesthesia in any animal. All regimens that induced a surgical plane of anesthesia caused bradycardia and bradypnea, and 75 mg/kg ketamine + 10 mg/kg xylazine and 100 mg/kg ketamine + 0.1 mg/kg dexmedetomidine caused the greatest decreases in SpO2. Except for one opossum that died of unknown causes, all animals remained healthy and apparently free of anesthetic complications. Among all treatments, isoflurane delivered by a precision vaporizer provided the most consistent and reliable anesthesia; therefore, we recommend inhalant anesthesia over the injectable combinations used in this study.

Demodex musculi, a prostigmatid mite that has been reported infrequently in laboratory mice, has been identified with increasing frequency in contemporary colonies of immunodeficient mice. Here we describe 2 episodes of D. musculi infestation with associated clinical signs in various genetically engineered mouse strains, as well as treatment strategies and an investigation into transmissibility and host susceptibility. The first case involved D. musculi associated with clinical signs and pathologic lesions in BALB/c-Tg(DO11.10)Il13(tm) mice, which have a defect in type 2 helper T cell (Th2) immunity. Subsequent investigation revealed mite transmission to both parental strains (BALB/c-Tg[DO11.10] and BALB/c-Il13(tm)), BALB/c-Il13/Il4(tm), and wild-type BALB/c. All Tg(DO11.10)Il13(tm) mice remained infested throughout the investigation, and D. musculi were recovered from all strains when they were cohoused with BALB/c-Tg(DO11.10)Il13(tm) index mice. However, only Il13(tm) and Il13/Il4(tm) mice demonstrated persistent infestation after index mice were removed. Only BALB/c-Tg(DO11.10)Il13(tm) showed clinical signs, suggesting that the phenotypic dysfunction of Th2 immunity is sufficient for persistent infestation, whereas clinical disease associated with D. musculi appears to be genotype-specific. This pattern was further exemplified in the second case, which involved NOD.Cg-Prkdc(scid)Il2r(tm1Wjl)/SzJ (NSG) and C;129S4 Rag2(tm1.1Flv) Il2rg(tm1.1Flv)/J mice with varying degrees of blepharitis, conjunctivitis, and facial pruritis. Topical amitraz decreased mite burden but did not eliminate infestation or markedly ameliorate clinical signs. Furthermore, mite burden began to increase by 1 mo posttreatment, suggesting that topical amitraz is an ineffective treatment for D. musculi. These experiences illustrate the need for vigilance regarding opportunistic and uncommon pathogens in rodent colonies, especially among mice with immunologic deficits.

Head-starting is an integral component of many chelonian conservation initiatives. However, the release of captive-raised individuals into wild populations carries the inherent risk of transmitting disease-causing microorganisms between the two populations, possibly with devastating consequences. Therefore, an essential component of any head-starting initiative is a preventive medicine program to identify and mitigate risks associated with disease transmission, and should include quarantine of captive animals as well as thorough health assessments of both captive and wild populations. Despite such efforts it is impossible to eliminate the risk of disease transmission, so prior to initiating head-starting projects a thorough risk assessment should be performed to ensure that the benefits of the project outweigh this risk.

Two aged female rhesus macaques (Macaca mulatta) presented with weight loss and intermittent inappetence. The signalment and constellation of clinical signs led clinicians to suspect the presence of intestinal adenocarcinoma. Because of each animal's advanced age and inconclusive radiographic findings, a noninvasive diagnostic tool was preferred over exploratory laparotomy to assist in determining a diagnosis. Consequently, 2-[(18)F]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography-CT (FDG-PET-CT) was chosen to aid in confirming a suspicion of gastrointestinal adenocarcinoma in both animals. FDG is a glucose analogue labeled with fluorine-18 and is taken up by highly metabolically active cells, as observed in many cancers. Tomography revealed an annular constriction of the small intestine with focal FDG uptake in one animal, and an FDG avid transmural mass in the ascending colon of the second animal. Necropsy later confirmed both sites to be adenocarcinomas. This report supports the use of FDG-PET-CT as an adjunct to conventional radiography in the diagnosis of intestinal adenocarcinoma in nonhuman primates.

Detection of mouse parvovirus (MPV) and other murine pathogens in research colonies is dependent on the transmissibility of the agents and the sensitivity of sentinels to those agents. Transmissibility is based on several agent-dependent properties including mode of transmission, infectivity, and environmental stability, whereas host susceptibility can vary according to mouse age, strain, and sex. In this study, 4-wk-old, 12-wk-old, and aged Swiss Webster female sentinel mice were compared for their ability to detect infectious agents by using a standardized health surveillance program, to determine whether sentinels should be replaced more frequently to improve the efficiency of detection of infectious agents within a murine colony. Both experimentally and naturally infected mice were used to transmit MPV and other infectious agents from index mice to sentinels. First, Swiss Webster mice were inoculated with MPV, and transmission to 4-, 12-, and 24-wk-old contact and soiled-bedding sentinels was determined. Second, mice naturally infected with 9 infectious agents were obtained from 2 local pet stores, and transmission to 4-wk-old contact sentinels and 4-, 12-, and 44-wk-old soiled-bedding sentinels was determined. For agents that were transmitted via soiled bedding (MPV, mouse hepatitis virus, murine norovirus, Theiler murine encephalomyelitis virus, and pinworms), transmission did not differ in regard to the age of the sentinels. In conclusion, susceptibility to several infectious agents did not differ according to sentinel age in a health-surveillance protocol that used mice older than 12 wk.

Peromyscus are myomorph rodents belonging to the family of Cricetidae and to the subfamily Neotominae. Neotominae comprises 16 genera of New World cricetid rodents including deer mice, woodrats, and their relatives. The white-footed mouse is the most commonly used in research. This chapter primarily describes the physical attributes, geographical habitat, lifespan, and uses in research of deer mice and white footed-mice. The chapter studies the infectious, bacterial, and viral diseases of deer mice. Despite their common names, deer mice and white-footed mice are not closely related to common laboratory mice of the genus Mus, or to laboratory rats (Rattus). Several inhalant and injectable anesthetic regimens have been used successfully in Peromyscus.

The goal of the current studies was to determine the risk of transmission of mouse parvovirus (MPV) by caging and husbandry practices. To determine whether MPV can be transmitted during cage changes in a biologic safety cabinet without the use of disinfectants, 14 cages of Swiss Webster mice were inoculated with MPV. Cages containing infected mice were interspersed among 14 cages housing naïve Swiss Webster mice. At 1, 2, and 4 wk after inoculation of the mice, cages were changed across each row. All naïve mice housed adjacent to infected mice remained seronegative. To determine the risk of environmental contamination, nesting pads that were used to sample the room floor during husbandry procedures at 1, 2, 4, and 6 wk after inoculation of the mice were placed in cages with naïve mice. None of the mice exposed to the pads became MPV seropositive. To determine whether components from cages that had housed MPV-infected mice could transmit MPV, Swiss Webster mice were exposed to soiled bedding or used cages, drinking valves, food, cage bottoms, wire bars and filter tops, nesting material, or shelters. With the exception of drinking valves, all mice exposed to other components became MPV seropositive. Fourteen cages that had housed MPV-infected mice were washed but not autoclaved; mice housed in the washed cages did not become MPV seropositive. In conclusion, all cage components can serve as fomites, with the drinking valve being the least risky. Cage washing alone was sufficient to remove or inactivate MPV.

Murine ulcerative dermatitis (UD) is a common progressive condition of mice with a C57BL/6 background. Typically, mice present with scabs and crusts on the skin of the dorsal neck and ears, and are often severely pruritic. Animals tend to scratch the lesions, causing additional trauma to the already ulcerated and inflamed skin. Therapeutic intervention largely has been unsuccessful, in part due to the lack of a known cause for the disease. Though the exact etiology of UD has not been elucidated, substance P (SP) has recently been demonstrated as an important neuropeptide linked to the itch-scratch cycle. SP functions at the tachykinin neurokinin 1 (NK1) receptor. We hypothesized that inhibition of SP binding to the NK1 receptor would decrease the itch sensation, thus decreasing scratching behavior and subsequent skin trauma. The purpose of this study was to evaluate the effectiveness of an NK1 receptor antagonist, maropitant citrate, as a treatment for murine UD. Treatment with 1 mg/kg maropitant citrate significantly reduced the size of UD lesions in mice.

Mouse parvovirus (MPV) remains a prevalent infection of laboratory mice. We developed 2 strategies to detect and control an active MPV infection over a 9.5-mo period. The first strategy used a test-and-cull approach in 12 rooms. After all cages corresponding to MPV-seropositive bedding sentinels were removed from the room, a naïve sentinel mouse was dedicated to every 2 to 3 rows per rack and received soiled bedding from these rows every 2 wk. All 12 rooms completed 3 consecutive negative rounds of targeted testing, which required an average of 20 wk. The second strategy used a modified quarantine approach to test unique mice that were critical for breeding. The process required removing selected cages from the seropositive rack and consolidating them to a single rack within the same room. All mice in these cages were tested by using MPV serology and fecal PCR. Cages were not moved, opened, or manipulated between sample collection and the availability of test results. The cages were relocated as a group to another room, because all mice were MPV negative. The mice were retested 3 wk after the initial testing, and all were MPV seronegative. Since the rooms were cleared 4 to 5 y ago, 7915 routine bedding sentinels and colony mice were tested from these rooms, all with negative results. These consistently negative MPV test results suggest that MPV was eliminated from these rooms, rather than driven down below the threshold of detection. These 2 strategies should be considered when confronting MPV infection.

Naturally occurring diabetes mellitus (DM) is common in several species of Old and New World nonhuman primates. Fructosamine values provide important information about recent glycemic control and can be useful in the diagnosis and management of DM. However, despite an abundance of reports in the literature describing spontaneous and induced DM in monkeys, few reference ranges are available for fructosamine. Reference ranges have been published for woolly monkeys (Lagothrix lagotricha), cynomolgus macaques (Macaca fascicularis), and stumptail macaques (Macaca arctoides) but currently are not available for rhesus macaques. At our institution, DM is a common diagnosis in aging rhesus macaques. Here we report a reference range for fructosamine in rhesus macaques. The overall range was 157 to 230 μmol/L, with male rhesus and macaques 10 y or older having significantly higher values than do female rhesus and macaques younger than 10 y, respectively. This range provides clinical veterinarians with an additional tool for evaluating glycemic control in rhesus macaques.