3 Minute 3Rs May 2019

3 Minute 3Rs

The May episode of 3-Minute 3Rs from the North American 3Rs Collaborative (www.na3rsc.org), the NC3Rs (www.nc3rs.org.uk), and Lab Animal (www.nature.com/laban)Papers:1. https://bit.ly/2vYuUPR2. https://go.nature.com/2w2tzre3. https://go.nature.com/2VEjEHz[NA3RC] Early mortality of pups in breeding colonies can reach upwards of 50% or higher depending upon the strain. While high pup mortality is often considered "normal", it instead may be indicative of an underestimated animal welfare issue that requires attention. Leidinger and colleagues investigate the influence of environmental enrichment as one way to mitigate early pup mortality rates. Enrichment, with nesting material and a shelter, protected against early mortality. Survival rates of pups born into enriched environments were more than double that of pups born into impoverished environments. The impoverished environment also had a negative impact on the developmental course of the remaining pups. Enrichment, among many potential benefits, may have reduced maternal stress and improved thermoregulation, which is particularly important for newborn pups. The findings suggest that early pup mortality is an animal welfare problem that can be improved through the characterization and selection of appropriate enrichment strategies. The refinement in breeding conditions can improve pup welfare and survival and lead to the need for smaller breeding colonies. [LA] Enrichment helps pups, check. But how can you tell how they’re doing in the first place? Invasive measures are challenging in such small animals, and pups lack features like fur and certain behaviors that can visually indicate health in adults. Dorothee Viemann and colleagues at Hannover Medical School recently proposed a new clinical health scoring system for neonatal mice to solve the pup assessment problem. They developed a score sheet based on observations of movement, nursing, and skin color and from quick examinations of capillary refill time, dehydration, reaction to tactile stimulus, and abdominal palpitation. They put their scoring to the test with healthy Black6 pup and two sepsis models known to cause mortality. The scoring correlated well with diseases, and was even more sensitive than blood-based biomarkers... [NC3Rs]…most creatures take great efforts to separate their ‘doings’ from anything else they do. Rodents especially will almost always have a dedicated latrine area away from their nest site. Laboratory mice, typically housed in small, open chambers are prevented from performing this instinctual behavior, and their nesting material is often found in close contact with their droppings. Joanna Makowska from the University of British Columbia and her colleagues have investigated how this housing arrangement affects the behavior of these animals. Groups of mice were kept in one of two housing systems. A standard single cage or a rather more luxurious series of three interconnected cages set up in a similar manner to rodent burrows in the wild. Mice in the triple cages were observed to segregate their nesting and latrine areas between different cages. Single cage mice attempted to separate these sites with their cage, urinating and defecating away from their nests. However the day to day movements of the animals invariably scattered the contents of the enclosure. Notably, mice housed in triple cages showed more affiliative behaviors, such as grooming or resting with one another than those in single enclosures. indicating a stronger social bond between the animals. They also were less disturbed by weekly cage cleaning, a typically stressful and highly disruptive event for lab mice. In the paper, published in Scientific Reports this April the authors conclude that mice find being housed in contact with their waste aversive, and that facilitating separation of nesting and latrine areas could be a simple, effective way of improving the welfare.

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