Rat Tickling

Animal-friendly handling is an important measure to ensure refinement in animal experimentation. On the one hand, it strengthens the human-animal relationship. Handling becomes more relaxed for both, less stress and fear are felt and the risk of injury is also significantly reduced. On the other hand, animal-friendly handling methods also have a positive influence on the quality of research, because negative influences such as stress can be reduced, which optimises the reproducibility of the results.¹

A group of neuroscientists, including Dr Jaak Panksepp and Dr Jeffrey Burgdorf, studied the behaviour of rats. They realised that young rats make sounds in the ultrasonic range (~50 kHz) when playing with conspecifics to express their pleasure. A typical rat game looks like this: a rat jumps on the neck of its playmate, which makes the latter turn on its back and hold on to the other. Based on this play behaviour, the researchers developed a new handling technique in which the rat play is imitated by human hands in order to trigger similar emotions in the animals. This method was called rat tickling. Other common terms are "playful handling", "heterospecific play", but also "rough-and-tumble-play".²

Some people will rightly ask whether every rat perceives tickling as a positive action or whether there are also animals that are not at all enthusiastic about it. Among humans alone, there are great differences in sensation and not everyone is equally ticklish. In fact, it has been proven that there are rats that do not like to be turned on their backs, for example, or others generally do not appreciate being tickled at all. Thus, it is important to cater to the individual needs of the animals. According to the research results of Hinchchliffe et. al. it is possible to determine the level of positive emotions based on the recorded ultrasonic sounds. Thus, these recordings can be used to determine for each rat whether it is a suitable handling method that is perceived as positive by the animal.³

Besides the concern that the animals might reject tickling, there is an assumption in research circles that implementing this technique in animal husbandry would take a lot of time. However, research shows that training sessions of 15 seconds per animal for 3 days would be enough to get the animals used to it and trigger positive emotions.⁴

In summary, it can be confirmed that animals, researchers and science as such benefit from this handling technique. But how does one acquire the necessary know-how and skills to be able to introduce rat tickling into the facility? On the one hand, there are many publications that deal with the topic and provide tickling protocols. Furthermore, there are videos demonstrating the practical implementation. There are even courses (online and hands-on) to learn this technique. However, results of a study show that it makes sense to also take a "hands-on" course to gain more confidence in the application of the technique.⁴

You can find more information on rat tickling here:

• Information and protocol: https://nc3rs.org.uk/3rs-resources/rat-tickling
• Video:https://www.jove.com/de/v/57190/tickling-a-technique-for-inducing-positive-affect-when-handling-rats (Sylvie Cloutier et al.; “Tickling, a Technique for Inducing Positive Affect When Handling Rats”)
• Protocol: Cloutier S et al. (2018). Tickling, a technique for inducing positive affect when handling rats. Journal of Visualized Experiments: JoVE 135: e57190. doi:10.3791/57190
• Backround und FAQ: https://www.na3rsc.org/rat-tickling-faq/

1) Morgan, K.N.; Tromborg, C.T. Sources of stress in captivity. Appl. Anim. Behav. Sci. 2007, 102, 262–302 Bailey, D.J. Does the Stress Inherent to Laboratory Life and Experimentation on Animals Adversely Affect Research Data? Altern. Lab. Anim. 2017
2) LaFollette MR, O'Haire ME, Cloutier S, Blankenberger WB, Gaskill BN. Rat tickling: A systematic review of applications, outcomes, and moderators. PLoS One. 2017 Apr 6;12(4):e0175320. doi: 10.1371/journal.pone.0175320 . PMID: 28384364 ;
PMCID: PMC5383284 LaFollette MR, O'Haire ME, Cloutier S, Gaskill BN. Practical rat tickling: determining an efficient and effective dosage of heterospecific play. Appl Anim Behav Sci. (2018) 208:82-91. doi: 10.1016/j.applanim.2018.08.005 Cloutier S, Wahl KL, Panksepp J, Newberry RC. Playful handling of laboratory rats is more beneficial when applied before than after routine injections. Appl Anim Behav Sci. (2015) 164:81–90. doi: 10.1016/j.applanim.2014.12.012
3) Bombail V et al. (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 Hinchcliffe JK, Mendl M, Robinson ESJ. Rat 50 kHz calls reflect graded tickling-induced positive emotion. Curr Biol. (2020) 30:R1034–5. doi: 10.1016/j.cub.2020.08.038
4) LaFollette MR et al. (2020). Changing human behavior to improve animal welfare: a longitudinal investigation of training laboratory animal personnel about heterospecific play or “rat tickling”. Animals 10(8): 1435. doi:10.3390/ani10081435