Table 3. Rat and Housing Characteristics of Tickled Rats.

First Author	Year	N	Strain	Sex	Age (days)	Rats per cage	Acclimation (days)
Boulay	2013	6–16	SD	M	21	4	1
Brudzynski	2011	66	LE	M	21	1	?
Burgdorf	2001	8–49	LE	M & F	37	1	?
	2005	240	LE	M & F	24	1	3
	2008	9	LE	M & F	31.5, 180	1, 3–5	?
	2009	18–83	LE	M & F	24–126	1	N/A
Cloutier	2008	40	SD	M	65	2	14
	2012	16, 32	SD	M	35, 57	1	?
	2013	72	SD	M	21	1, 2, 3	3
	2014	48	SD	M	25	1, 2, 3	4
	2015	96	SD	M	32	1	11
Garcia	2015	20, 30	SD	M	40	1	10
	2016	30	SD	M	40	1	10
Hori	2009	8	Wistar	M	28	1	7
	2013a	12	Fisher	M	37.5	1	5
	2013b	79	Fisher	M	25	1	14
	2014	95	Fisher	M	21	1, 3	5
Koiv	2016	40	Wistar	M	22	4	?
Mallo	2007	29, 58	Wistar	M & F	22	1, 4	0
	2009	62	Wistar	M & F	21	1, 4	0
Natusch	2010	12	Wistar	M	70	6	3
Panksepp	2000	12–48	LE	M & F	28–50	1, 2	?
Paredes-Ramos	2012	20, 30	?	F	31, 92	1	?, 5
Popik	2012	40	SD	M	?	4	7
	2014	33	SD	M	?	5	7
Raudkivi	2012	40	Wistar	M	21	1, 3–4	0
Roccaro	2016	37	Wistar	M & F	21	1	?
Rygula	2012	26	SD	M	?	4	7
Schwarting	2007	20	Wistar	M	?	1	4
Wöhr	2009	18	Wistar	M	49	1	3
Yamamuro	2010	12	Wistar	?	28	1	7
	2013	70	Wistar	?	28	1	7

Key characteristics about the rats used and their housing from 56 experiments from 32 articles about rat tickling. Rats per cage indicates the number of rats that were housed in each cage during the experiment. When articles had 2 experiments with different values those values are split by a comma. Articles with >2 experiments with different values have a dash indicating the range of values used.? = unclear or not reported. N/A = not applicable