Washington ? Investigators tentatively traced the first U.S. cow with mad cow disease to Canada, which could help determine the scope of the outbreak and might even limit the economic damage to the American beef industry.

Dr. Ron DeHaven, the Agriculture Department’s chief veterinarian, said on Saturday that Canadian officials provided records indicating the sick Holstein was in a herd of 74 cattle shipped from Alberta, Canada, into this country in August 2001 at Eastport, Idaho.

“These animals were all dairy cattle and entered the U.S. only about two or two-and-a-half years ago, so most of them are still likely alive,” DeHaven said.

The sick cow’s presence in that herd does not mean all 74 animals are infected, DeHaven said. Investigators probably will find where the other 73 animals are within a matter of days, he said. Finding them will help investigators determine if any other animals are sick and need to be tested.

In May, Canada found a lone cow with the disease in Alberta but has not been able to determine the source of infection.

If U.S. and Canadian officials confirm that the sick cow in Washington state came from Canada, it might save the export market for the American beef industry because the United States could keep its disease-free status and continue trade.

Federal officials announced on Tuesday that tests indicated the cow, which ended up at a Washington farm in October 2001, had mad cow, a brain-wasting illness. An international laboratory in England confirmed it Thursday.

Mad cow disease, known as bovine spongiform encephalopathy, is a concern because humans who eat brain or spinal matter from an infected cow can develop variant Creutzfeldt-Jakob disease. In Britain, 143 people died of it after an outbreak of mad cow in the 1980s.

Federal officials insist U.S. meat is safe because the brain, spinal cord and lower intestine — parts that carry infection — were removed from the cow before its meat was processed for human consumption.

Cows eat at the dairy farm Sunny Dene Ranch Saturday in Mabton, Wash. The farm has been quarantined by the state because a cow from the farm has been infected with mad cow disease.

Despite those assurances, more than two dozen countries banned U.S. beef last week. The United States lost 90 percent of its beef export market, industry officials say, and producers stand to lose up to $6 billion a year in exports and falling domestic prices. Agriculture Department officials went Saturday to Japan, a top buyer that has banned American beef, to discuss maintaining trade.

Connecting the infected cow to Canada could deal another blow to the Canadian beef industry, which has struggled since it found its case of mad cow last May. It lost $1 million in beef trade per day as countries cut off beef imports.