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Teenagers in Russia and the former Soviet Union have been dressing up as dogs and cats and attacking people in a viral trend that politicians want to ban.
Known as quadrobers, the teenagers wear masks and paws and crawl around on all fours, barking, growling and meowing.
In Uzbekistan, a former Soviet state in Central Asia, police are on the hunt for at least one teenager, dressed as a dog, who bit a passer-by.
Video, from inside a shop, showed a group of quadrobers, lumbering along a pavement in Tashkent wearing masks and tails. Other photos showed a girl dressed as a cat goading a dog.
The Uzbek interior ministry has now threatened to fine the parents of teenagers 1.9 million Uzbek soum (about £112) for quadrobing.
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It said: “Experts believe that ‘quadrobics’ can lead to the child taking on the aggressive actions of animals, injuring himself and others, and can lead to damage to the child’s not yet fully formed psyche, as well as to his isolation from society.”
Quadrobics is believed to have been invented by Kenichi Ito, a Japanese sprinter who set a world record bounding along a 100m track on all fours like an ape or monkey in 2008, and then again in 2015.
He studied how apes moved and used to practice his technique as he washed floors in his job as a caretaker.
Quadrobers not only mimic various animals, wearing masks, costumes and tails, but they also emphasise their athletic prowess.
The trend appears to have migrated from Japan and North America this year and has been spotted in Russia, Kazakhstan, Uzbekistan and Ukraine.
In September, Natalia Kosikhina, a Russian senator, proposed banning quadrobics because it was “unsafe”.
“I believe that we need to make sure that children are more interested in sports and educational activities that would not harm the psyche and health of others,” she said.
Other psychotherapists, though, have said that quadrobics is a harmless pastime and part of children’s play.