Laboratory animal professionals (LAP) are faced with various situations and tasks influencing their mental well-being. A systematic review has been conducted to investigate whether there are specific stressors for LAP and which moderators are relevant for the development of psychological strain. A comprehensive search following PRISMA Guidelines was carried out in June 2021. Results include 12 studies and have been summarized qualitatively in narrative synthesis and tabular presentation. Available literature indicates that LAP are facing stressors but does not allow for conclusions on specific stressful job duties other than euthanasia. Signs of strain are present in LAP. Specifically, participants in qualitative studies reported acute symptoms, while chronic manifestations were in focus in quantitative studies. Although a wide variety of moderating factors have been investigated, only social support has been rated as relevant by multiple qualitative and quantitative studies without contrasting results. According to current data, there is a risk for psychological strain in LAP. However, there is limited understanding of specific stressors and data on moderators is diverse. Further studies that focus on domain-specific knowledge and clearly distinguish stressors from moderators are necessary to set up institutional programmes addressing psychological strain in LAP.

Specific experimental protocols necessitate transportation, a potentially stressful event that could confound results. We determined adrenocortical activity by measuring fecal corticosterone metabolites (FCMs), as a stress marker, in prepuberal (three-week old) female C57BL/6J, C57BL/6NCrl, FVB/NCrl, Crl:CD1(ICR), and BALB/cAnCrl mice. On each transport day, five female cage mates per genetic background were weaned and transported in stable groups via truck from the breeding to the research facility. Fecal pellets were collected on Days 0, 1, and 4. Mice were superovulated for embryo production to determine if repeated fecal collection impacts this procedure. The average duration of transportation over 600 km and from packing to unpacking of mice was 7.24 and 22.62 h, respectively. FCM levels increased from Day 0 to Day 1 and decreased on Day 4 in all genetic backgrounds except in FVB/NCrl, but only B6N showed significantly higher FCM levels on Day 1. Furthermore, embryo production was not affected by repeated feces collection. The results show that weaning and immediate transport of prepuberal mice from the breeding to the research facility led to temporal and genetic background-dependent increases of adrenocortical activity in four of the five genetic backgrounds investigated, which returned to baseline levels within four days.