A diverse microbial community and common core microbiota associated with the gonad of female Parascaris spp.

The microbiome plays an important role in health, where changes in microbiota composition can have significant downstream effects within the host, and host-microbiota relationships can be exploited to affect health outcomes. Parasitic helminths affect animals globally, but an exploration of their microbiota has been limited, despite the development of anti-Wolbachia drugs to help control infections with some filarial nematodes. The equine ascarids, Parascaris spp., are considered the most pathogenic nematodes affecting juvenile horses and are also the only ascarid parasite to have developed widespread anthelmintic resistance. The aim of this study was to characterize the microbiota of this helminth, focusing on the female gonad, determine a core microbiota for this organ, identify bacterial species, and show bacterial localization to the female gonad via in situ hybridization (ISH). A total of 22 gonads were isolated from female Parascaris spp. collected from three foals, and 9 female parasites were formalin-fixed and paraffin-embedded for ISH. Next-generation sequencing was performed using V3-V4 primers as well as the Swift Amplicon™ 16S+ ITS Panel. Overall, ten genera were identified as members of the Parascaris spp. female gonad and twelve bacterial species were identified. The most prevalent genus was Mycoplasma, followed by Reyranella, and there were no differences in alpha diversity between parasites from different horses. Specific eubacteria staining was identified in both the intestine and within the gonad using ISH. Overall, this study provided in-depth information regarding the female Parascaris spp. microbiota and was the first to identify the core microbiota within a specific parasite organ.

The Effect of Inhaled Ciclesonide Treatment on Systemic Markers of Immune Function in Horses.

The use of dexamethasone to control equine asthma is a common and effective treatment. Although short-term systemic dexamethasone treatment has not been shown to induce systemic immunosuppression in the horse, the goal of this study was to determine whether inhaled ciclesonide, an FDA-approved drug for the treatment of equine asthma, exerts any systemic immunosuppressive effects when compared to dexamethasone-treated and untreated horses. Eighteen light, mixed breed horses, ranging in age from 3 to 8 years of age, were used for this study and randomly assigned to one of three treatment groups: (1) nontreated controls, (2) ciclesonide treatment, or (3) dexamethasone treatment. Blood was collected daily for steady-state messenger RNA (mRNA) analysis, as well as at Days 0, 5, 10, and 15 of treatment for in vitro stimulation with Concanavalin A (ConA). Messenger RNA relative quantities were determined using RT-qPCR for select genes. Two-way, repeated measures analysis of variance was used to analyze qPCR data and results considered significant at P < .05. There were significant decreases in the steady-state, whole-blood expression of granzyme B and interferon-γ due to dexamethasone treatment, when compared to the nontreated control group. Within ConA-stimulated samples, there remained a suppressive effect of dexamethasone treatment on granzyme B expression compared to nontreated control horses. Similar effects were not noted in the ciclesonide-treated horses. Significant effects of ciclesonide treatment on markers of immune function were not noted in this study, suggesting a low risk for immunosuppression with inhaled ciclesonide treatment.

Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Effects of Various Commercially Available Enrichment Options on Handling and Chronic Stress Markers in Female ICR Mice.

Although social housing of mice generally is preferred, mice must be individually housed in some situations. In these cases, enhanced attention to environmental enrichment is encouraged, but few studies assess the wellbeing of mice provided various enrichments. In this study, we used female ICR mice to evaluate enrichment strategies that encouraged natural behaviors including foraging, exercise, sheltering, and socialization. After 3 mo of exposure to the assigned enrichment strategy, wellbeing was assessed by evaluating behavioral and physiologic differences between groups. The results suggested that the use of red-tinted igloos may decrease markers of mouse wellbeing. However, none of the selected strategies yielded measures of wellbeing indicating improvement as compared to individually housed mice with no enrichment (negative control). Furthermore, measures were not significantly different between paired mice and individually housed mice with no enrichment.

Evaluation of the neutrophil-lymphocyte ratio as a measure of distress in rats.

The ability to evaluate distress in laboratory animals is needed in order to ensure that husbandry and experimental procedures do not negatively impact animal welfare. Accurate measurement of acute stress and chronic stress, and distinguishing between stress that is harmful (distress) and stress that does no harm (eustress), can be challenging. Whereas corticosterone concentrations are commonly used to measure stress in laboratory animals, the neutrophil-lymphocyte ratio has been proposed as a potentially better indicator of chronic stress. Furthermore, an association between such measures of stress and concurrent behavioral indicators of negative welfare is required to determine their accuracy in evaluating distress. The authors compared serum corticosterone concentrations and neutrophil-lymphocyte ratios to assess acute or chronic stress in male Sprague Dawley rats. Elevated serum corticosterone concentrations, but not neutrophil-lymphocyte ratios, were associated with acute stress exposure, whereas elevated neutrophil-lymphocyte ratios, but not serum corticosterone concentrations, were associated with chronic stress exposure. Because the neutrophil-lymphocyte ratio differences corresponded with a behavioral indicator of distress in chronically stressed rats, it may serve as a valuable tool for the physiological assessment of distress in rats.

Effects of age of pups and removal of existing litter on pup survival during cross-fostering between multiparous outbred mice.

Periparturient manipulation of mice is a valuable tool for modern research facilities. Although fostering and Caesarian section frequently are used to eradicate pathogens, an often overlooked use is to rescue poorly breeding strains of mice. Here we characterized the weaning success rates after fostering outbred pups of variable ages (younger than 24 h; 5 to 7 d; 10 to 12 d) with full or partial replacement of litters and multiparous dams. There were no significant differences between most groups when analyzed by full or partial replacement or age of donor pups as compared with control groups, in which pups were manipulated but returned to the birth dam or the birth dam was not disturbed. However, significant differences were associated with fostering of 10- to 12-d-old pups in combination with younger pups. Overall, these findings suggest that limiting fostering to pups that are within 48 h of age and age-matching litters when fostering are unnecessary.

Use of a body condition score technique to assess health status in a rat model of polycystic kidney disease.

Simple and noninvasive methods of assessing health and wellbeing are valuable when performing clinical evaluation of rodents used in biomedical research. Body condition score (BCS) techniques have been described for a variety of species, including mice. This method can be a sensitive objective assessment of weight loss in animal models where organ enlargement, ascites, or tumor development may mask weight loss. Although deposition of fat is similar in rats and mice, the mouse BCS technique has not been characterized in rats. Here we used the Han:SPRD rat model for polycystic kidney disease to characterize the effectiveness of the mouse BCS scale when applied to rats. This study showed a positive correlation between BCS score and renal function and a negative correlation between weight and renal function, supporting the use of BCS as an effective, noninvasive method of health assessment in this rat model. Our results also demonstrate that the BCS scale described for mice required a slight modification to capture the delay in fat deposition over the lumbar vertebrae in obese animals.

A cost-effective and efficacious method of pinworm treatment for large colonies of mice.

Rodent pinworm infestations are common in modern animal facilities, and treatments to eradicate these nematodes are often costly and labor-intensive. The authors describe a method they developed to treat rodents with ivermectin using the automatic watering system available at their facility. This delivery method proved an efficacious and cost-effective means of eradicating Aspiculuris tetraptera from a large colony of mice. The system might also be used to provide other orally administered agents to mice and other species.