The world's donkeys are experiencing a global massacre like never before. In the next five years, more than half their population could be wiped out, according to a new report from the international charity Donkey Sanctuary; and it's all because of their precious hides.

When soaked and stewed, the skin of the donkey can be boiled down into a sort of gelatin glue called ejiao, which is used as an ingredient in traditional Chinese medicine.

Over the past few decades, demand for ejiao has gone through the roof, according to the Donkey Sanctuary. Today, the industry requires approximately 4.8 million donkey skins per year, causing China's own donkey herd to reduce by 76 percent since 1992.

It's hard to get exact numbers on these practices, as much of the trade is illegal and unregulated, but research suggests from 2013 to 2016, the annual production of ejiao increased from 3,200 to 5,600 tonnes, which is a 20 percent boost per year.

A little more than a third of that comes from donkey skins in China. The rest must be sourced elsewhere. As prices and demand continue to increase, Chinese skin traders have resorted to buying hides from developing countries and transporting them back home.

Last year, in fact, a large ejiao producer called Dong-E-E-Jiao confirmed that China imported 3.5 million donkey skins in 2016 alone, and in some places like Brazil and Africa, this has led to a collapse in national donkey populations.

"These dependable, hard working, sentient animals experience appalling suffering as a result of the activities of skin traders across the world," writes Mike Baker, CEO of the Donkey Sanctuary, in the foreword for the charity's new report.

"They are often transported long distances, without food, water or rest and they can be held for days in yards without shelter, before being slaughtered in often brutal conditions."

EjiaoA block of donkey hide gelatin. (Deadkid dk/Wikimedia Commons/CC BY 3.0)

Animal scientist Amy McLean from the University of California, Davis told Science Magazine the donkey's current plight is "horrific", and not just for them. As the world loses this work animal in ever more astonishing numbers, people are having to shoulder the burden themselves. And that's especially true for women.

"Working donkeys in Africa are instrumental in lessening the burdens placed on women, enabling them more time to care for their children and families," the Donkey Sanctuary explains in the report.

"Women who must carry firewood and water on their backs or heads are often forced to leave their young children at home, or to struggle carrying both."

Donkeys support the livelihoods of an estimated 500 million people around the world in some of the poorest communities, but now, this crucial rug is being pulled out from beneath them.

In Kenya, up to 378,000 donkeys are slaughtered every year and the government says this has put relentless pressure on their people by removing a vital source of transport and income.

The problem is not just in Africa, either. According to the report, Brazil's donkey numbers have dropped 28 percent in a mere decade and that doesn't even count roaming donkeys. Mauritania, Mexico, Peru and Egypt all have a legal trade, but even in Ghana and Ethiopia, where the practice is illegal, these animals are still dying.

And the product isn't just staying in China. Last year, an investigative report revealed that when it comes to the biggest exporters of ejiao from China, the USA, Canada, Australia and Japan are all in the top ten.

Some even worry that the donkey hide trade will ultimately lead to an extinction of this species in some nations. While that may sound hyperbolic at first, donkeys are slow to reproduce and evidence suggests it would take over 20 years to breed the millions of hides demanded by the world each year.

In short, there are simply not enough animals to sustain this burgeoning industry, and the Donkey Sanctuary is demanding an urgent halt to the global trade.

"Where the trade operates legally, it has grown so rapidly in size and complexity that it is almost entirely unregulated, with no means of monitoring the welfare of donkeys, or of tracking the source of individual skins," reads the report.

"Where the slaughter of donkeys and the export of their skins is illegal, donkeys are being stolen and traded indiscriminately in defiance of national and local laws and cultural traditions."

The Donkey Sanctuary report can be found in several languages here.