Physiological and behavioural responses of laboratory rats housed at different tier levels and levels of visual contact with conspecifics and humans

Laboratory rats are typically housed in clear or opaque cages on multi-tiered racks. Clear-walled cages allow a view of the room and facilitate visual social contact with neighbouring rats but may induce anxiety due to lack of visual cover. We hypothesized that degree of visibility of humans and conspecifics affects anxiety in individually housed rats. […]