It all went wrong when the rhino fell into convulsions. Ten men struggled to control the giant animal as its twitching grew worse. Its head suddenly lurched, almost knocking over a veterinarian with its huge horn.
Until that moment, the operation seemed to be going smoothly. While the rhino wheezed and snorted under anesthetic, the vets drilled holes in its horn and applied an experimental new treatment, injecting the horn with an indelible dye and a toxic pesticide to deter poachers.
But when the 50-minute procedure was nearly over, the rhino's heartbeat became more erratic. And when the vets tried to wake it up, there was no response. The rhino was dead.
"It's a tragedy, it's a disaster," said Charles van Niekerk, the veterinarian who developed the anti-poaching infusion technique.
He was close to tears today after the death of the rhino at a wildlife park near Johannesburg – the first death he has experienced after conducting the experimental treatment on more than 10 rhinos so far. A post-mortem will be conducted, but he refused to promise an end to the experiment.
"The easy way out is to say 'No more' – but then the poachers win," he said.
"We're being driven by a desperate need to do something. We had to begin sooner than we wanted to, but if we waited three or four years, are we going to have any rhinos left?"
The experimental treatment is the latest emergency response to a poaching crisis that threatens to decimate the world's rhino population. South Africa, home to the vast majority of the world's rhinos, saw more than 400 of its rhinos killed by poachers last year alone, and the death rate increased again last month.
The soaring rate of poaching deaths could soon jeopardize the future of the rhino, reversing the normal growth of the species.
The demand is fueled by the economic boom in Vietnam and China, where newly affluent consumers are convinced that rhino horn can cure cancer and other illnesses. (In fact, it has no medical value.)
The toxic pesticide, injected in rhino horns in the anti-poaching campaign, is intended to destroy the demand for illegally killed rhino, since the chemical could cause illness in anyone who consumes it.
The pink indelible dye in the horn, combined with microchips, tracking devices and DNA samples, is designed as further protection for the rhinos and an easier way to identify poachers.
The treatment is the only legally recognized method of "poisoning" a rhino horn, since its practitioners have obtained a legal opinion that the pesticide has legitimate uses for rhinos and isn't deliberately intended to cause harm.
After the death of the rhino today, veterinarians said the animal might have had a chronic heart condition and could have died of a heart attack. Believed to be about 20 years old, the male rhino was relatively old, and it was impossible to test its health before the operation.
Lorinda Hern, whose father owns the wildlife park where the rhino was treated, wept with emotion as she described the rhino, which was named Spencer and had been in the park for about 10 years.
But she said the operation had been conducted properly and responsibly, and it has inherent risks that could not be completely eliminated.
Joseph Okori, manager of an African rhino program at the World Wide Fund for Nature, defended the treatment today after witnessing the death. "This is an experiment that we're not going to say should be stopped," he said.
"This is an unfortunate event, but they carried out all due processes. The benefits outweigh the risks. This is a crisis situation, and it is important that all possible options are explored, even if it does involve some risks."