Four endangered white rhinoceroses have died within days of one another at an Australian zoo, leaving vets and breeders scrambling for an explanation.
The rhinos, part of a breeding program at Western Plains Zoo at Dubbo in the state of New South Wales, "died suddenly after showing some neurologic abnormalities such as stumbling," according to ABC News.
Australia's ABC Online reported that staff were carrying out a range of tests in cooperation with rhinoceros specialists in Africa and North America.
The remaining three white rhinos in the herd are being monitored.
"We're working around the clock and consulting with rhinoceros specialists in Africa as well as specialist virologists in the hope of finding the cause," the Fairfax press quoted Ben Bryant, the zoo's head vet, as saying.
They had so far ruled out exposure to toxins, bacterial infections, snake bite, organ failure, Hendra Virus and West Nile Virus.
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According to the Fairfax press, Intombi and her calf, Amira, as well as two other rhinos, Izizi and Aluka, began showing signs of neurological abnormalities a couple of weeks ago.
"The rhino keepers and veterinary staff know and care for every individual in the herd, so this has been a huge shock," said the zoo's general manager, Matt Fuller.
"Our focus is on continuing this investigation to pinpoint the cause."
Meanwhile, Greens Senator Lee Rhiannon had called for an independent inquiry into the Endangered Species Breeding Program — the second time representatives of the political party have made such a call.
Their first call came after the death in 2007 of Kua, a pregnant rhino destined for Western Plains Zoo for breeding. At the time, it is alleged her death was caused by inadequate care.
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"Captive breeding programs are contentious, with animals exposed to a variety of health threats," Rhiannon reportedly said. "Captivity poses its own threats to the survival of animals not experienced in the wild."
She said a US research paper had concluded that black rhinos in captivity displayed unusual disease syndromes not described in the wild.
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"Any captivity that does not replicate rhinos' natural habitat increases stress. It is well known that stress compromises the immune system
"With viruses most virulent before they cause death, there could well be other animals infected at the zoo."
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