Ejiao is the name of a traditional Chinese medicine that supposedly treats anemia, reproductive issues and insomnia – though the alleged medicinal properties are unproven. Nonetheless, it's an ingredient in tonics and face creams. Sales of the products are a multimillion dollar business.
And it's quite literally killing the world's donkeys.
Millions of donkeys each year are slaughtered so manufacturers in China can boil the skins to extract the gelatin, which is used to make ejiao.
According to a 2016 report from Chinese state-run news agency Xinhua, around 4 million donkey hides are needed each year to produce enough ejiao for the market in China, but the annual supply of donkeys from China is fewer than 1.8 million.
To fill the gap, China is importing donkey skins from developing countries where there are populations of relatively cheap animals.
"The industrial scale at which these animals are being slaughtered is an issue of massive concern," says Simon Pope, rapid response manager at Donkey Sanctuary. "It's probably the biggest issue facing donkeys ever."
This year Brooke of the United Kingdom became the latest international animal welfare group to condemn the donkey skins trade.
"The effect we're seeing on the African donkey population is proving even greater than we originally feared," says Petra Ingram, chief executive of the charity, which focuses on working horses, donkeys and mules. "In taking away someone's donkey, it can mean taking away their means of making a living, potentially for a dangerously long time."
"The rate of decline we're witnessing in the donkey populations of some African countries is dramatic and unsustainable," says Geoffrey Dennis, chief executive of SPANA, a charity that seeks to improve the welfare of working animals in poor communities.
Burkina Faso, Ghana, Ivory Coast, Kenya, Nigeria, South Africa and Tanzania are among the countries where the donkey population is threatened by voracious demand for their skins, according to animal welfare charities.
The donkey population in Botswana, for example, has decreased 39 percent from 229,000 in 2014 to 142,000 in 2016, according to SPANA.
In early 2018, SPANA staff in Mali reported that 2,000 donkeys were being sold for slaughter every week at the country's seven major livestock markets.
Dr. Matthew Stone, deputy director general, International Standards and Science, at the World Organisation for Animal Health (OIE), believes the situation is worsening. Because of demand for ejiao, the legal and illegal trade of donkey products "has recently increased, causing major impacts on the rural livelihoods, donkey populations health and welfare and the environment worldwide," he says.
The problem is also spreading in countries such as Brazil.
"The industry is growing so fast that existing laws haven't caught up," says Pope of Donkey Sanctuary, who visited the country last fall. He interviewed people on the ground who told him that donkeys might be transported long distances for several days by truck and are given no food or water while they await slaughter in overcrowded pens.
Some of these donkeys are stolen from their owners, according to reports obtained by the animal rights groups. For example, 705 donkeys were stolen in Kajiado County, Kenya between December 2016 and March 2017, according to Brooke East Africa — as reported by donkey owners to the group's local partner organizations.
And while many donkeys are slaughtered in legal, government-sanctioned slaughterhouses, these stolen donkeys often end up in small-scale slaughterhouses, which kill them under inhumane conditions, according to a report from Donkey Sanctuary.
This kind of inhumane donkey slaughter is especially acute in Africa, the groups say, where China has a strong presence because of business ventures, such as building large infrastructure projects.
One of the pilfered animals belonged to Francis Dayou of Kenya, who owned a donkey that transported water in the town of Naivasha.
In his community, "donkeys are very important," he says. People rely on them for transporting farm goods, people and water.
But his donkey, named Master, was stolen in 2017.
That was "very painful," recalls Dayou. Without income from transporting water, he had difficulty paying his high school fees. He had to do lower-paying work: transporting goods with a wheelbarrow, odd jobs on construction sites.
Dayou reported the theft to the police, but they couldn't trace the donkey.
He's well aware of the donkey skins trade. "It should be closed straight away. All donkeys are being taken away," he says.
Even when owners willingly sell a spare donkey to make money, they may not realize the long-term impact on their livelihoods. With skins in such high demand, prices for donkeys have doubled, tripled or quadrupled so owners can't replace donkeys they have sold or buy new ones if their donkeys are stolen.
In Kenya, for example, prices jumped from $40 per animal to over $160 from February to August 2017
Donkeys that are left behind are worked even harder.
Breeding more donkeys is not a solution. With a 10-to-14 month period of gestation, the animals can't be bred fast enough to fulfill demands for ejiao.
Donkeys are also prone to hyperlipemia, a stress-related condition that can cause them to drop dead or suffer spontaneous abortions.
"If you were going to breed an animal, donkeys wouldn't be top of most people's list," Pope of Donkey Sanctuary observes.
So the charity is lobbying African governments to enforce existing restrictions on the skin trade. It also lobbied e-commerce website eBay, which agreed to stop selling ejiao products in Dec. 2017.
Other countries have put a halt to slaughter and export. In Zimbabwe, a slaughterhouse had proposed killing about 12,000 donkeys per year. "That would have equated to a loss of almost a tenth of the country's donkey population in just 12 months," estimates Dennis from SPANA. Those plans were halted in 2017. Botswana and Tanzania in 2017 followed Niger, which banned exports and restricted the skins trade in 2016.
In 2017, Uganda banned the trading of donkeys for slaughter and ordered closures of donkey slaughterhouses. The decision was reportedly due to the negative consequences on households that rely on donkeys to transport everything from water to harvested foods to be sold at market.
But such steps don't necessarily stop the trade.
"In some cases, this has led to the emergence of a black market and an explosion in donkey thefts," says Dennis.
SPANA last year called for an immediate halt to the ejiao trade in Africa while its impact is assessed.
It is working closely with a number of African governments to implement bans or restrictions on slaughtering donkeys and exporting donkey products.
Both SPANA and Donkey Sanctuary are training people to build fenced corrals for donkeys to secure the animals. Some people in Kenya are bringing donkeys into their huts at night and sleeping next to them to protect them, says Pope.
Donkey Sanctuary is also helping to run workshops with local authorities and police to enforce bans on the illegal trade, track the underground trade and take action on reports of stolen donkeys.
Brooke is working with communities to raise awareness of the consequences of the skin trade. "We're making sure owners understand the life-time value of donkeys and the significant risk to livelihoods of sale for immediate income," says Whear.
In 2017, Brooke East Africa invited more than 200 donkey welfare groups in Kenya to share ideas about reducing donkey thefts. They included lockable donkey shelters, solar powered security lights, guard dogs, and community surveillance hubs, though implementation depends on funding and resources.
Both SPANA and Donkey Sanctuary are training people on building fenced corrals for donkeys and securing the animals.
Donkey Sanctuary is also helping to run workshops with local authorities and police to enforce bans, track the underground trade, and take action on reports of stolen donkeys. Some people in Kenya are bringing donkeys into their huts at night and sleeping next to them to protect them, notes Pope.
Tracking and stopping a booming and often illicit trade in Africa and South America is a huge task for relatively small animal welfare non-profits such as Donkey Sanctuary.
"When the sanctuary was set up, we didn't think we'd ever be doing this kind of work," says Pope, who worked in anti-wildlife poaching in Namibia before joining Donkey Sanctuary. "We're horrified it's come to this. We've got to rise to the challenge. It's the biggest thing this organization has done and will do."
Amy Yee has written for The New York Times, The Economist, NPR and other outlets. She is a former staff journalist for the Financial Times.