A mapping review of refinements to laboratory rat housing and husbandry.

Refining the housing and husbandry of laboratory rats is an important goal, both for ethical reasons and to allow better quality research. We conducted a mapping review of 1,017 studies investigating potential refinements of housing and husbandry of the laboratory rat to assess what refinements have, and have not, been studied, and to briefly assess whether there is evidence to support any impact on rat welfare. Among the many refinements studied, the majority involve changes to the cage, but some also involve alterations to the wider environment. The effects of these refinements were assessed using a range of readouts, many of which are difficult to interpret from a welfare perspective. Preference studies, which are easier to interpret, provide evidence that rats prefer complex environments, including shelters and multiple objects, which offer different areas/resources allowing the rat to engage in diverse behaviors. The reporting of methodology in papers was often poor, indicating that studies were potentially subject to biases. Given that many refinements co-occurred, it was often difficult to tease apart which ones were most beneficial for rat welfare. Effects of refinements were also moderated by a number of factors including age, sex, strain and photoperiod. Altogether our findings show that a one-size-fits-all approach to refinements is not appropriate, because different refinements will impact different rats in different ways. Our review has also produced a database of >1,000 articles that can be used for further and more detailed analyses. Our findings have also highlighted areas where future research is likely to be valuable, including refinements to rat transport, handling and the use of training.

That brachycephalic look: Infant-like facial appearance in short-muzzled dog breeds.

Brachycephalic dog breeds are highly popular, yet their conformation-related disorders represent a major welfare concern. It has been suggested that the current popularity of such breeds can be explained by their cute, infant-like facial appearances. The concept of 'kindchenschema' refers to the observation that certain physical features of infant humans and other animals can automatically stimulate positive and nurturant feelings in adult observers. But the proposal that brachycephalic dogs possess heightened 'kindchenschema' facial features, even into adulthood, has never been formally investigated. Here, we hypothesised that relative muzzle shortening across a range of breeds would be associated with known 'kindchenschema' facial features, including a relatively larger forehead, larger eyes and smaller nose. Relative fronto-facial feature sizes in exemplar photographs of adult dogs from 42 popular breeds were measured and associated with existing data on the relative muzzle length and height-at-withers of the same breeds. Our results show that, in adulthood, shorter-muzzled breeds have relatively larger (taller) foreheads and relatively larger eyes (i.e. area of exposed eyeball relative to overall face area) than longer-muzzled breeds, and that this effect is independent of breed size. In sum, brachycephalic dog breeds do show exaggeration of some, but not all, known fronto-facial 'kindchenschema' features, and this may well contribute to their apparently cute appearance and to their current popularity as companion animals. We conclude that the challenge of addressing conformation-related disorders in companion dogs needs to take account of the cute, 'kindchenschema' looks that many owners are likely to be attracted to.