A dog sits with a competitor dressed as Santa Claus before an annual charity Santa fun run in Loughborough, central England December 7, 2014. (Photo by Darren Staples/Reuters)

A fox runs out onto the pitch before the start of the second half. Celtic League 2012/13, Round 19, Leinster v Ulster, RDS, Ballsbridge, Dublin, March 30, 2013. (Photo by Paul Mohan)

Transgender contestants run backstage before the final of the annual Miss Tiffany's Universe 2014 transvestite contest in the beach resort town of Pattaya, May 2, 2014. The contest aims to promote a positive image of transvestites. (Photo by Athit Perawongmetha/Reuters)

Participants cross cold and muddy waters during the Strong Race competition near Tukums May 4, 2014. About 6500 people competed in this extreme running race, which includes cross-country running, elements of agility and power discipline. (Photo by Ints Kalnins/Reuters)

Participants dressed as Santa Claus take part in the Great Edinburgh Santa Run on December 11, 2011 in Edinburgh, Scotland. Around a thousand people took part in the annual fundraising event, with all money raised being donated to the charity “When You Wish Upon a Star”. (Photo by Jeff J. Mitchell/Getty Images)

Participants take pictures of themselves as others run past the Tiananmen gate during the Beijing Marathon in Beijing, China, September 17, 2016. (Photo by Damir Sagolj/Reuters)

People run in panic after a coalition airstrike hit Islamic State fighters positions in Tahrir neighbourhood of Mosul, Iraq, November 17, 2016. (Photo by Goran Tomasevic/Reuters)

Participants enjoy the “Color Me Run” festival in Hanoi, Vietnam, 28 May 2016. The festival which was inspired by the Holi Festival from India, attracted thousands of teenagers this year. (Photo by Luong Thai Linh/EPA)