Nguyen Huong Giang loves to party but loathes hangovers, so she ends her whiskey benders by tossing back shots of rhino horn ground with water on a special ceramic plate.
Her father gave her the 4-inch (10-centimeter) brown horn as a gift, claiming it cures everything from headaches to cancer. Vietnam has become so obsessed with the fingernail-like substance it now sells for more than cocaine.
"I don't know how much it costs," said Giang, 24, after showing off the horn in her high-rise apartment overlooking the capital, Hanoi. "I only know it's expensive."
Experts say Vietnam's surging demand is threatening to wipe out the world's remaining rhinoceros populations, which recovered from the brink of extinction after the 1970s thanks to conservation campaigns. Illegal killings in Africa hit the highest recorded level in 2011 and are expected to worsen this year.
This week South Africa called for renewed cooperation with Vietnam after a "shocking number" of rhinos have already been reported dead this year.
China has long valued rhino horn for its purported _ though unproven _ medicinal properties, but U.S. officials and international wildlife experts now say Vietnam's recent intense craving, blamed partly on a widespread rumor that rhino horn cures cancer, is putting unprecedented pressure on the world's estimated 28,000 remaining animals, mainly in South Africa.
"It's a very dire situation," U.S. Fish and Wildlife Service Director Dan Ashe said by telephone. "We have very little cushion for these populations in the wild."
Although data on the global rhino horn trade is scarce, poaching in Africa has soared in the past two years, with American officials saying China and Vietnam are driving the trade that has no "significant" end market in the United States.
Wildlife advocates say that over the last decade, rhino horn has become a must-have luxury item for some Vietnamese nouveau riche, alongside Gucci bags and Maybach cars.
Between 2006 and 2008, three diplomats at the Vietnamese Embassy in Pretoria were linked to embarrassing rhino trafficking scandals _ including one caught on tape. In February, U.S. agents busted an alleged interstate rhino horn trafficking syndicate with Vietnamese-American ringleaders.
A court affidavit obtained by The Associated Press alleges one of those arrested in the U.S. case, Felix Kha, traveled to China 12 times between 2004 and 2011 and went to Vietnam five times last year.
"There are still horns going into China, but Vietnam is driving the increase in poaching for horns," said Chris R. Shepherd, deputy regional director for Southeast Asia at the wildlife advocacy group TRAFFIC. "Vietnamese authorities really need to step up their efforts to find out who is behind horn trafficking ... and put them out of business."
The rhino horn craze offers bigger payoffs than other exotic wildlife products such as bear bile or tiger bone paste. American officials say the crushed powder fetches up to $55,000 per kilogram in Asia ($25,000 per pound) _ a price that can top the U.S. street value of cocaine, making the hoof-like substance literally as valuable as gold.
The drive is so great, thieves are now pinching rhino horns from European museums and taxidermy shops, sometimes smashing them off with sledgehammers before fleeing. According to Europol, the European law enforcement agency, 72 rhino horns were stolen from 15 European countries in 2011, the first year such data was recorded.
Poachers in South Africa are also using chain saws to rip rhinos' horns off, mutilating the hulky animals while they're still alive and leaving oozing bloody cavities in the heads of those lucky enough to survive.
Sometimes, they simply shoot the beasts dead, even though the horns can grow back within two years without harming the animal if carefully cut. Officials and nonprofits in South Africa are preemptively cutting some rhinos' horns in an attempt to save them, but some poachers are killing anyway just for the nubs.
Vietnam wiped out its own last known Javan rhinoceros in 2010 despite efforts to protect it. The last of the population was found dead in a national park, shot through the leg with its horn hacked off.
Tran Dang Trung, who manages a zoo outside Hanoi that imported four white rhinos from South Africa, said he worries for the animals' safety even though the zoo has 24-hour security.
"If thieves wanted to kill the animals and steal their valuable parts, they could," Trung said recently outside the rhinos' basketball court-sized outdoor pen.
Laws in Vietnam surrounding the business of importing horns are murky and crackdowns are rare despite government pledges to root out traffickers.
Officially, no more than 60 horns are legally imported into Vietnam as trophies bagged from South African game farms each year, but international wildlife experts have estimated the actual number of trophy horns taken by Vietnamese nationals from South Africa each year may exceed 100.
Albi Modise, spokesman for South Africa's Department of Environmental Affairs, said Wednesday the department is concerned about the difficulty of identifying Vietnamese who request permits and whether they have the means for big game hunting.
"It became pretty clear that there seemed to be some funding from outside individuals" of Vietnamese hunters, Modise said. "We're concerned as a department that evidently there are people who exploiting the permit system."
But he said that rather than imposing a blanket ban on Vietnamese hunters, the department is trying to resolve its concerns through diplomatic channels. Hanoi has also been asked to conduct inspections to make sure rhino trophies imported from South Africa still remain in the hunters' possession.
It's impossible to track how other rhino horns are entering Vietnam, wildlife advocates say, but they point to local media reports suggesting Vietnamese diplomats are implicated in the international trade that's been largely banned since 1976.
In 2006, a diplomat at Vietnam's South African Embassy was arrested for trafficking rhino horn, while another was filmed two years later trading the substance outside the mission's gates. A third diplomat was also questioned that same year after 18 kilograms (40 pounds) of rhino horn was found in his car outside a casino.
In a statement, Foreign Ministry Spokesman Luong Thanh Nghi said those incidents reflected badly upon Vietnam's image and that the diplomats all faced disciplinary measures.
Meanwhile, illegal rhino killings in South Africa are skyrocketing _ from 122 in 2009 to 333 in 2010 and a record 448 in 2011. The country reported last week that 150 rhinos had already been poached this year, nearly 60 percent taken from Kruger National Park.
In Hanoi, Vietnamese buy rhino horn on the streets of the bustling old quarter, where a traditional medicine dealer recently told the AP that the average prescription costs 200,000 dong ($10).
Hanoi doctors report that some of their clients take the powder as a supplement to western medicines, believing it cures fever and other common ailments. Others use it as a last-ditch effort against cancer.
Nguyen Huu Truong, a doctor at Hanoi's Center for Allergy Clinical Immunology, said a handful of patients visit him each year complaining of rashes he links to rhino horn consumption.
"Many Vietnamese believe that anything expensive is good, but if you're going to spend a lot of money on rhino horn, you might as well bite your nails," he said. Rhino horns are composed of keratin, a protein found in human hair and fingernails.
Giang, the young Vietnamese woman who regularly uses rhino horn to prevent hangovers, says she's unfazed by doctors' assessments of the substance's efficacy and doesn't care to know how her father acquired the horn.
Experts say some rhino horns passing through Vietnam are fakes, and the AP couldn't verify the authenticity of Giang's horn, which she grinds on a plate with a rough finish made specifically for the task. She ingests the liquefied form when she has allergic reactions or after tippling on too much top-shelf liquor.
Because Giang only takes rhino horn shots once or twice every three months, she estimates her horn will last another 10 to 15 years. But once her stash is depleted, there may not be any rhinos left on earth to satisfy her craving.
Associated Press writer Donna Bryson in Johannesburg, South Africa, contributed to this report.