Tokyo Japan's government announced Monday it has found the country's and Asia's first suspected case of mad cow disease and blamed imported feed as the likely cause.
Japanese health experts had previously asserted the high standards of cleanliness in Japanese cattle ranches would keep the country free of the brain-wasting disease, which has ravaged herds in Britain and elsewhere in Europe and is believed linked to a fatal human disease.
But officials were alarmed last month when a cow in Shiroi in Chiba prefecture mysteriously lost the ability to stand.
The animal was slaughtered and tests of its brain indicate signs of the illness, according to a statement issued Monday by the Ministry of Agriculture.
"We must now ask ourselves if our previous way of thinking was wrong, if there were factors we hadn't foreseen," said Kiyoshi Onodera, deputy division chief at the Ministry of Agriculture's animal health division.
The government said more tests were necessary to determine conclusively whether the cow was infected with the disease. Earlier testing in August had come up negative.
Milk produced by the 5-year-old Holstein had already been sold on the market before the slaughter, but scientists believe milk is unlikely to spread the disease.
The cow was destroyed and its meat was not sold.