What’s the best way to tickle a rat?

There’s an art – a science, really – to tickling a rat. They like a bit of rough and tumble, can be irked by soft caresses, and tend to enjoy it more when in or close to bed, with mood lighting. But don’t bother if you’ve just stuck your rat with a hypodermic needle; no matter how good your technique, the animal won’t appreciate the effort.

These are some of the insights from a new meta-analysis of 32 significant studies of rat-tickling over the past 17 years conducted by a team of animal welfare experts primarily from Purdue University in Indiana. The research assesses the benefits of tickling rats and seeks to address the “insufficient guidance” for scientists using tickling in laboratory experiments. 

Scientists have been tickling rats with serious intent since the pioneering work of rat fondlers (and neuroscience researchers) Jaak Panksepp and Jeff Burgdorf of Bowling Green State University, Ohio, who first published research on the positive response of rats to tickling in 2000, measured through the rats’ expression of ultrasonic vocalisations associated also with play, mating, exploratory activity, anticipation of food rewards and amphetamine administration. 

A lab rat’s life can be stressful, even when it doesn’t involve being forced to run mazes, injected with drugs or having electrodes inserted in the brain. Since Panksepp and Burgdorf’s work, scientists have been experimenting with techniques of “rat-tickling” to improve lab rats’ mood and well-being, both for the inherent animal-welfare benefits and to avoid potentially misleading results from experiments using anxious or depressed rats.

The new research, led by Megan LaFollett of Purdue University’s Center for Animal Welfare Science, affirms the generally positive effect of rat-tickling, both to improve rat welfare and for advancing research on human health, since measuring how a rewarding experience affects the neurology of laboratory animals can provide insights to treating depression and anxiety.

“We conclude that tickling is a promising method for improving rat welfare and investigating positive affect,” LaFollett and her co-authors report. “However, the establishment of tickling best practices is essential as the outcomes from tickling can be moderated by several factors.”

Noting that the term “tickling” is imprecise, covering a variety of approaches to touching rats, the researchers emphasise the need for future rat-tickling research to include more rigorous reporting of methods and conditions, to determine “ideal tickling duration and frequency” as well as the consequences of variables such as the presence of bedding, light intensity, and the time of day at which tickling takes place. 

Until then, the researches endorse using the “original” rat-tickling method devised by Panksepp and Burgdorf. The method mimics rat rough-and-tumble play through contact with the back of the neck and stomach. Each tickling session should last for two minutes, alternating between 15 seconds of rest and 15 seconds of active tickling, with daily sessions for at least five days. 

A notable gap in rat-tickling research, the researchers say, has been the lack of attention given to the potential benefits for the rats’ human caretakers. “Animal care personnel, particularly those involved in euthanasia, report mild to moderate traumatic general stress, higher level of work stress, and may have higher employee turnover,” the research notes. “Therefore, it is important to consider caretaker outcomes, in addition to animal outcomes, when investigating human-animal interactions such as tickling.”