When a team of Chinese cyclists on a 1,000 mile-long expedition from Chengdu to Tibet threw a stray dog a bone, they may not have thought they would attract a companion who would run with them for the entire length of their journey.
Over the course of the journey, the dog climbed over 12 mountains that were higher than 13,000ft
The loyal stray, who has been named Xiao Sa, or Little Sa, followed the cyclists for 20 days, and has now become a sensation in China.
The group came across the dog five days after leaving Chengdu, in the mountains around Yajiang, a Tibetan area of Sichuan.
One of the cyclists, 22-year-old Xiao Yong, spotted the small white mongrel and threw her a chicken drumstick. To his surprise, Xiao Sa began to follow them.
Over the course of the journey, the dog climbed over 12 mountains that were higher than 13,000ft, and stuck with the group during heavy storms.
Indeed, as cyclist after cyclist dropped out of the expedition, exhausted by the steep mountains and the thin air of the Tibetan plateau, the dog kept him and his colleagues going, said Mr Xiao.
"There was one day when we climbed the 14,700ft-tall peak of Anijula mountain," he said.
"We did more than 40 miles uphill and at the end I had to get off and push my bike instead. But the dog ran ahead of me and stopped at a crossroads. She waited for a while, but got bored because I took so long, so ran back, put her paws on my calves, and started licking me.
I could see she cared about me," he said.
He said the dog had enough energy to run with the cyclists for at least 30 miles to 40 miles each day, but that he would sometimes pick her up if she was tired and carry her along in a makeshift box on the back of his bicycle.
At night, she slept on the team's raincoats, but there were a couple of occasions when she cuddled up to Mr Xiao for warmth, he said. The team also decided to share their rations with the dog, feeding her custard tarts, boiled eggs and sausages.
At first, Mr Xiao said he suspected the dog of only following them for food, especially as other cyclists in Sichuan had reported seeing her follow them in the past. "But I can now see a bond between us from the way she looks at me," he said. "I think we have definitely moved beyond food." There were also fierce encounters with other dogs along the way.
"Once, a large dog started chasing us along a series of dark tunnels and his barking drew a whole pack of others. I put Xiao Sa on my bike and started peddling desperately. One of my bags was ripped, but otherwise we got away," he said.
On Monday, Xiao Sa was on her way back to Chengdu by aeroplane, after being adopted by Xiao Yong and getting a full medical from a vet in Lhasa, who pronounced her free of altitude sickness.
Chinese internet users have nicknamed the dog Forrest Gump, in honour of her simple-minded stamina, and cheered to see photographs of the dog in front of Lhasa's Potala Palace.
Give a dog a bone and he'll run 1,000 miles - Telegraph