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In this observational retrospective study, an outbreak of Staphylococcus aureus abscesses was correlated with the presence of sharp edges in damaged plastic environmental enrichment within the cages. In 2010, Lawson reported cases of S. aureus mandibulofacial and maxillofacial abscess in mice and proposed excessive barbering or grooming, leading to the mastication and fragmentation of hair, as an aetiopathogenesis of S. aureus abscesses. In contrast, in this study, the presence of hair was not found in any of the histopathology, and abscesses were present in the periorbital area. S. aureus colonises the skin, nasopharynx and intestines, and may cause pyogenic infections if a breach in local defences promotes staphylococcal invasion. Whole genome sequencing and analysis supported the hypothesis that this outbreak resulted from clonal expansion of S. aureus infected C57BL6/J mice imported into the area and infection transmission from humans to mice was ruled out. An additional aetiopathogenesis is proposed for S. aureus abscesses with the sharp edges of damaged plastic environmental enrichment items leading to oral mucosal injury allowing S. aureus entrance into tissues, its carriage into the submucosa, followed by abscess formation. [ABSTRACT FROM AUTHOR]

Inbred mouse strains have long proved useful as tools for biomedical research. They remove the effects of genetic background as an experimental variable. Within all mouse colonies, genetic drift is a recognised phenomenon and monitoring and documenting changes is important for experimental design and consistency. This communication documents the initial characterisation through SNP analysis of the inbred mouse strains bred and used at the time at the Medical Research Council National Institute for Medical Research (MRC-NIMR), Mill Hill, now The Crick Institute. These inbred strains were part of the foundation colonies for the many genetically modified mouse strains made at Mill Hill. We found small genetic changes in four of the nine inbred strains. Although phenotypic differences have not yet been found between the NIMR and the correspondent parental strains, I cannot discard that these may arise or have already arisen. This work has also authenticated the 129/SvJEvNimr-Gpi1c strain that was widely used at MRC-NIMR for gene targeting. All these inbred strains have been renamed according to The International Committee on Standardized Genetic Nomenclature for Mice. [ABSTRACT FROM AUTHOR]

Laboratory Animals Limited (LAL) is a charity that promotes education and training in all the aspects related to the care and welfare of these animals. Twenty-first century laboratory animal medicine should be moving, as Steven M Niemi pointed out almost a decade ago,[2] in the direction of treating patients, not reagents with "use by" dates. [Extracted from the article]

Caring for animals aiming for better science: Directive 2010/63/EU on protection of animals used for scientific purposes: Animal welfare bodies and national committees. Addressing, defining and, if necessary, enforcing a "Culture of Care", based on the 3Rs, animal welfare and regulatory oversight, in every animal research establishment in Europe is both important and essential; however, it is not the whole story, and we ought not delude ourselves into thinking that it is. In this issue of I Laboratory Animals i , Fabienne Ferrara and her collaborators[1] explore the fashionable concept of "Culture of Care" with a novel and important angle. [Extracted from the article]

Mycobacterium gordonae is an occasional human pathogen associated with cutaneous infections and nodular granulomatous skin lesions. A case of cutaneous nodular infection caused by M. gordonae in a colony of African clawed frogs (Xenopus tropicalis) is described and confirms this organism to be an opportunistic frog pathogen. [ABSTRACT FROM AUTHOR]

Simple Summary: Mice is the most used species in the biomedical research laboratory setting. Scientists are constantly striving to find new tools to assess their welfare, in order to ameliorate husbandry conditions, leading to a better life and scientific data. Steroid hormones can provide information regarding different behavioral tracts of laboratory animals but their quantification often require stressful sampling procedures. Hair represents a good, less invasive, alternative in such scenario and is also indicative of longer timespan due to hormones' accumulation. The aim of the work was to quantify steroid hormones in the hair of male laboratory mice and to look for differences imputable to age and housing conditions (pairs VS groups). Age influenced all analysed hormones by increasing testosterone and dehydroepiandrosterone (DHEA) levels and decreasing corticosterone. When comparing animals housed in pairs VS groups, the only difference found was a higher level of DHEA in mice housed in groups. Due to the nature of DHEA, this finding may suggest that group housing may be beneficial for social interaction. In conclusion, it seems that hair hormones quantification may be a good tool for welfare assessment in laboratory mice and may help in refining husbandry. Steroids, providing information regarding several biological patterns including stress and sexual behavior, have been investigated in different matrices in laboratory mice. Data regarding hair quantification, indicative of longer timespans when compared to blood and saliva, are lacking. The aim of the work was to analyze the hormonal hair profile of laboratory male mice and to investigate potential relationships with age and housing, as a potential tool for welfare assessment. Fifty-six adult male C57BL/6J and C57BL/6OlaHsd substrain mice were included in the study, housed in pairs or groups. Testosterone (T) and dehydroepiandrosterone (DHEA) were quantified by radioimmunoassay, corticosterone (CORT) by ELISA. Mean hormone levels were 6.42 pg/mg for T, 23.16 pg/mg for DHEA and 502.1 pg/mg for CORT. Age influenced all hormones by significantly increasing T and DHEA levels and decreasing CORT; only DHEA, significantly higher in grouped mice, was influenced by housing conditions. The influence of age indicates the need for accurate age-related reference intervals, while the higher levels of DHEA in grouped animals suggests that such housing practice may be beneficial for social interactions. In conclusion, it seems that hair hormones quantification may be a good tool for welfare assessment in laboratory mice and may help in refining husbandry. [ABSTRACT FROM AUTHOR]