Bouwer says the De Wildt center recently saw such a case.
"Fortunately we were able to dart the animal [with a tranquilizer] and remove the thorn without damage to its sight," she said.
Researchers attribute the growing number of cheetah injuries mostly to an increase in big cats hunting on foreign terrain.
The cats normally hunt on grassland, but the reserves in which many cheetahs are placed are mostly bushy. Denser, shrubby ecosystems are also encroaching on grasslands in many areas.
Observers have reported the most eye and facial injuries to cheetahs in Namibia, South Africa's northwestern neighbor.
Veterinarians there have been called in to study the problem.
Bonny Schumann, research assistant at the Namibia-based Cheetah Conservation Fund, blames the high accident rate on bushy terrain.
"Cheetah are basically grassland hunters," Schumann said. "But over recent years the habitat has changed considerably to thorny acacia tree types."
She says heavier rains and cattle farming have encouraged shrubs and trees to encroach on grassland areas.
"Cheetah seem to have adapted well to the changing habitat. Still it has become noticeable how many sustain eye injuries."
Henk Bertshinger heads the wildlife studies program for the veterinary science faculty at the University of Pretoria, South Africa.
He doesn't think cheetah injury rates are unusualparticularly for predators that run as fast as many of us drive.
"It is just their daily hazard of being a wildlife species, the way a lion risks getting its stomach ripped open by a horn or its jaw broken by the hoof of a buffalo it is trying to bring down."
"It is a problem for [cheetahs], but I don't think it impacts on their survival," he said.
A co-owner of Makulu Makete, a private game reserve in northern South Africa, says she recently observed the accidental death of one of the reserves two introduced cheetahs.
Writing in her reserve's newsletter, Jane Chidgey says she followed the source of a static radio-collar signal and spotted Dottie, a female cheetah.
"Dottie raised her head out of the grass, then stood up and took a few steps before flopping down," she wrote.
"To our horror we saw that she was badly injured, with her intestines hanging out from a wound under her belly."
The cheetah died, but her four cubs were found and have been sent to the De Wildt center.
(See National Geographic magazine's Growing Up Cheetah.)
Photographer and businessperson Howard Buffett, the son of U.S. billionaire investor Warren Buffett, photographed a similar accident.
The pictures and description of the incidents appear in a book Spots Before Your Eyes, which Buffett co-authored with De Wildt's founder, Ann van Dyk.
Buffett describes a fatal accident experienced by a female cheetah chasing an impala ram at about 50 miles an hour (80 kilometers an hour) on a South African reserve.
"The [cheetah], during the chase, clears a short log and does not compensate for two broken branches. The rigid branches split the cheetah's sides as if a hunter has gutted her. She emerges with flesh and guts almost dragging on the ground," he wrote.
That cheetah died, but its cubs were also found and delivered to De Wildt.
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