Ultrasonic vocalizations as indicators of welfare for laboratory rats (Rattus norvegicus) (2007)

Burman, O. H. P., Ilyat, A., Jones, G. et al.

Abstract

Adult laboratory rats produce two distinct types of ultrasonic vocalization (USV) that appear to reflect the caller's emotional state, either positive (50 kHz) or negative (22 kHz). If these calls can influence the emotional state and related behaviour of group-mates, then such calls may act as useful indicators of welfare for not only the vocalizing rat, but also other non-vocalizing individuals within auditory range. We therefore investigated the effect of playing back these different USVs on the behaviour of rats in an emergence test, a test of anxiety. The results suggest that 22 kHz USVs can induce a negative emotional state of increased anxiety in rats hearing the vocalization, and could therefore be a useful indicator of welfare for rat groups; including both callers and non-calling group-mates.