Cage Size Preference in Rats in the Laboratory

The size of an enclosure is an integral part of how well it accommodates a nonhuman animal’s welfare; however, most enrichment studies concentrate on modifying the area inside the enclosure rather than enlarging it. It has been suggested that rats have little need for more cage space, but there is no empirical evidence about rats’ […]

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. […]

Let sleeping rats lie: Does the timing of husbandry procedures affect laboratory rat behaviour, physiology and welfare?

Research has indicated that chronic stress can reduce sleep quality and quantity. Yet there has been little investigation into whether husbandry procedures carried out during an animal’s normal sleeping period affect subsequent sleep behaviour and welfare. We housed 48 rats in enriched cages containing four rats, in either a light phase treatment (LPT) (n=6 cages) […]

Preference for familiar humans by rats

Many “higher” animals are commonly assumed to distinguish between individual humans. This belief is based largely on anecdotal reports; in reality, there is little empirical evidence to support human recognition in nonhuman species. Wereport that laboratory rats consistently chose a familiar human over an unfamiliar human following fourteen and five IO-min exposures and even following […]

Can sleep behaviour be used as an indicator of stress in group-housed rats (Rattus norvegicus)?

We assessed the value of sleep behaviour as a novel measure of stress in group-housed animals. We observed, non-invasively, sleep behaviour in 144 group-housed rats, and related it to other physiological and physical indicators of stress and welfare. Sleep frequency and duration correlated negatively with adrenal weight, and positively with bodyweight gain, and final bodyweight. […]

The welfare impact of gavaging laboratory rats

Gavaging (oral dosing) has previously been shown to have only a short-term effect on behavioural parameters in the laboratory rat. The aim of this study was to determine if the gavaging of laboratory rats influenced their heart rate, blood pressure and body temperature, and if so, whether the duration of this impact correlated with the […]

Long-term social memory in the laboratory rat (Rattus norvegicus)

A key question in the management of group-housed captive animals is how long can an individual be removed from a social group and still be reintroduced with minimal social upheaval. In order to answer this question we require a knowledge of how long cage-mates, following a specified period of group-housing, can remember one another after […]

Playful handling as social enrichment for individually- and group-housed laboratory rats

Social housing is recommended for laboratory rats because they are highly social mammals but research constraints or medical issues often demand individual housing and, when social housing is practiced, it typically involves housing with only one or two conspecifics. We hypothesized that playful social contact with humans (i.e. tickling), mimicking the dorsal contacts and pins […]

The effects of witnessing managemental procedures during the light versus the dark phase of the light cycle on behaviour, performance and welfare of laboratory rats

Research has indicated that witnessing managemental procedures are stressful to laboratory rats. Yet there has been little investigation into whether the time of witnessing these procedures affects behaviour and welfare in these animals. Ninety-six rats, representing two batches, were used in this study. Forty-eight of them were housed, in groups of four, in either light […]

Experimental Control for the Ovariectomized Rat Model: Use of Sham Versus Nonmanipulated Animal

One of 2 models required by the U.S. Food and Drug Administration for registration of a treatment for osteoporosis, the ovariectomized (OVX) rat model, is widely used in scientific studies investigating sex hormone-deficient bone loss. The use of control nonhuman animals is critical because bone turnover may be affected by animal stress, use of anesthetic, […]