Tickling Rats for Superior Science

By Megan LaFollette

When I meet new people, they usually ask me what I do for a living. I love the opportunity to answer, “I study the intersection of animal welfare and human-animal interaction, specifically rat tickling” People are always curious to hear more, although sometimes they think I must be joking. Surely I don’t really tickle rats for my job!

Rat tickling? What is that? Why would you do that?

Rat tickling is a technique that humans can use to mimic rat rough-and-tumble play and interact with rats [1]. It’s similar to if you’ve ever played and run around with your dog, feinting, dodging, and getting down low, maybe wrestling a tad. Similar to dogs, juvenile rats play by running around and taking turns wrestling with one rat on top of the other. Obviously, we can’t wrestle a rat with our whole body, we would crush them! But we can use our hand to mimic rat play, which is the technique of rat tickling.

Researchers and pet rat owners tickle rats for a couple of reasons. The reason I am most interested in is to improve rat welfare. Initially, when we interact with rats they are afraid of us. For lab rats especially, this fear continues when scientists do things like give them injections, which can be common in scientific studies. This fear can cause stress, anxiety, and possibly interfere with scientific results. Fortunately, rat tickling can help. By tickling rats, we can reduce their fear of humans, decrease stress during injection, and increase positive emotions [2].

Is rat tickling really scientific? It seems a little silly to me.

Rat tickling is a scientifically based technique. As my colleagues and I showed in our recent systematic review about rat tickling, there have been over 32 articles and 56 experiments that use rat tickling [3]. Several of these articles looked at the welfare benefits of rat tickling. Others focused on using rat tickling to study and model positive emotions. For example, does being predisposed to being happier help in coping with stress? Scientists have used rat tickling to help answer this question [4]. They found that indeed, some rats consistently respond better to tickling than others (thought to be inherently happier) and these rats were more stress-resilient than those who respond more negatively to tickling (thought to be inherently less happy).

Do rats really like tickling? It looks pretty rough to me.

Rat tickling is supposed to be a rough and rambunctious; after all it mimics rat rough-and-tumble play. Almost all of the 22 experiments comparing rat tickling to other types of rat handling show that tickling rats is positive. To be specific, rat tickling results in increased positive vocalizations, faster approach to humans, and more positive responses to handling, as well as decreased anxiety.

Seeing positive vocalizations in response to tickling is a particularly exciting result. Rats make ultrasonic vocalizations in the 50-kHz range when they have positive experiences, and these vocalizations are therefore thought to reflect positive emotions [5]. Some scientists even think these 50-kHz ultrasonic vocalizations are actually analogous to human laughter; so it is not inaccurate to say that rats laugh when you tickle them [6].

References

  1. Burgdorf J, Panksepp J. Tickling induces reward in adolescent rats. Physiol Behav. 2001;72: 167–173. doi:10.1016/S0031-9384(00)00411-X
  2. Cloutier S, Panksepp J, Newberry RC. Playful handling by caretakers reduces fear of humans in the laboratory rat. Appl Anim Behav Sci. 2012;140: 161–171. doi:10.1016/j.applanim.2012.06.001
  3. LaFollette MR, O’Haire ME, Cloutier S, Blankenberger WB, Gaskill BN. Rat tickling: A systematic review of applications, outcomes, and moderators. PLOS ONE. 2017;12: e0175320. doi:10.1371/journal.pone.0175320
  4. Mällo T, Matrov D, Kõiv K, Harro J. Effect of chronic stress on behavior and cerebral oxidative metabolism in rats with high or low positive affect. Neuroscience. 2009;164: 963–974. doi: 10.1016/j.neuroscience.2009.08.041
  5. Burgdorf J, Panksepp J, Moskal JR. Frequency-modulated 50 kHz ultrasonic vocalizations: a tool for uncovering the molecular substrates of positive affect. Neurosci Biobehav Rev. 2011;35: 1831–1836. doi:10.1016/j.neubiorev.2010.11.011
  6. Panksepp J, Burgdorf J. “Laughing” rats and the evolutionary antecedents of human joy? Physiol Behav. 2003;79: 533–547. doi:10.1016/S0031-9384(03)00159-8

About the Author:

Megan LaFollette is a 2nd year PhD student at Purdue University. She works with Dr. Maggie O’Haire on Human-Animal Interaction and Dr. Brianna Gaskill on Laboratory Animal Welfare Science. Her research focuses on using rat tickling to enhance laboratory animal welfare and its effects on both rats and the humans that interact with them. Outside of her PhD, Megan is an avid traveler and loves the pursuit of acrobatic yoga.

LaFollette

The ISAZ Student Blog is posted every-other month and each post is authored by a different student member of the International Society for Anthrozoology. Interested in authoring a post? Please see our submissions page for details on how to apply.

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