High laboratory mouse pre-weaning mortality associated with litter overlap, advanced dam age, small and large litters

• DOI: 10.1371/journal.pone.0236290
• Publication Date: 2020-08-12T17:39:47Z
• Authors: Gabriela M. Morello; Jan Hultgren; Sara Capas-Peneda; Marc Wiltshire; Aurelie Thomas; Hannah Wardle-Jones; Sophie Brajon; Colin Gilbert; I. Anna S. Olsson
• Keywords: Litter; Animal Husbandry; Cage; Laboratory mouse

High and variable pre-weaning mortality is a persistent problem in laboratory mouse breeding. Assuming modest 15% rate across strains, means that approximately 1 million more pups are produced yearly the EU to compensate for those which die. This paper presents first large study under practical husbandry conditions determine risk factors associated with mortality. We analysed historical records from 219,975 two breeding facilities, collected as part of their management routine including information on number born weaned per litter, parents’ age identification, dates birth death all animals. Pups were counted once week life at weaning, every one or weeks, depending need cage cleaning. Dead recorded soon these found during daily screening (without opening cage). It was hypothesized litter overlap (i.e. presence older siblings when new born), recurrent social configuration trio-housed mice, increased newborn mortality, along advanced dam age, size, high cage. The estimated probability pup seven percentage points higher cages compared without. Litter an increase entire five six points, represent 19% 103% non-overlapped litters respectively. Increased siblings, small size (less than four born) (over 11 death.