Authorities say 410 pigs and 122 dogs were found dead Monday in homes and at farms in a village in central Henan province.
Local authorities say chemical factories in the area have been ordered to suspend production. The chief of Yanshi city's propaganda office says the deaths are suspected to be related to the factories.
Authorities say the deaths have nothing to do with the bird flu virus that recently spread to humans.
Last month, more than 16,000 dead pigs were found in rivers supplying water to Shanghai. The dumping has not been explained, though police had been cracking down on the illegal sale of pork products made from dead, diseased pigs.
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