Rats emit ultrasonic vocalisations (USVs) in the 50 kHz range when a human hand imitates the rough-and-tumble play seen between young rats. Such vocalisations indicate that the rats are enjoying themselves, as USVs have been linked with positive emotions, are emitted during social play, and may be homologous to human laughter. However, rats differ in their response to playful handling. A recent publication questions whether current methods overemphasise the use of pinning, where the rat is flipped onto its back followed by rapid and forceful tickling of its belly. The authors suggest that methods used for playful handling should incorporate more aspects of play (increased diversity) and be adapted to the responses of individual rats (increased flexibility). This is to promote positive emotions and achieve increased welfare across a wider cohort of rats.
The article can be found here: https://doi.org/10.3389/fvets.2021.677872
Bombail, V., Brown, S.M., Hammond, T.J., Meddle, S.L., Nielsen, B.L., Tivey, E.K.L., and Lawrence, A.B. (2021). Crying with laughter: adapting the tickling protocol to address individual differences among rats in their response to playful handling. Frontiers in Veterinary Science 8: 677872. DOI: 10.3389/fvets.2021.677872
Image credit: Tayla J. Hammond
