It’s been two weeks since the USDA announced a Washington state dairy cow had tested positive for BSE (bovine spongiform encephalopathy, known as mad cow disease). Since then both U.S. and Canadian officials have confirmed the cow was born in Canada before a 1997 ban went into effect in both countries on feed containing potentially infectious material.

The cow, slaughtered on December 9, was imported with 80 other cattle two years ago. Both countries have been trying to locate the remaining animals, but only 10 have been found so far at Washington farms that remain under quarantine. Dr. Brian Evans, chief veterinary officer of the Canadian Food Inspection Agency, says Canadian records show an additional 17 young cows were from the same herd, including a calf by the infected animal that entered the United States. USDA officials say they are still trying to confirm that information.

In the meantime, the USDA identified a herd in Washington containing a calf by the sick cow. The calves were not tagged. With the single calf not identifiable and questions about whether mad cow disease can be passed from mother to calf, the USDA required the entire herd to be slaughtered. Federal workers sedated the calves and administered lethal injections at a vacant slaughterhouse Tuesday.

The USDA has tightened its regulations, ruling that non-ambulatory animals – the infected cow could not walk—cannot enter the human food supply. All animals also must now be processed using the highly regulated advanced meat recovery (AMR) process. Sen. Tom Daschle (D-S.D.) and other lawmakers want even further regulation, calling on the USDA to require all animals to be tested at slaughter. The American Meat Institute says such a practice is unnecessary and wasteful, given the disease manifests itself in cattle over 30 months old, while most cattle are slaughtered at younger ages. The USDA last week banned high-risk nervous system material from cattle over 30 months of age.

Daschle also has joined with other lawmakers from the Midwest in calling on Agriculture Secretary Ann Veneman to temporarily close the border to all Canadian beef products.

U.S. officials continue to negotiate with international trading partners—particularly Japan, the largest U.S. beef customer—to reopen their borders to U.S. beef. Japan is sending officials to the U.S. to discuss the matter, but shows no signs of lifting the ban without agreement from the U.S. to test all food cattle.

Meanwhile, Japanese fast-food chain Yoshinoya says it may stop serving its trademark beef-and-onions rice dish until authorities resume U.S. beef imports. Yoshinoya President Shuji Abe says the chain will run out of beef supplies in February, and that Japanese and Australian beef are far too expensive for use in the budget-priced dish.

McDonald’s Japan has taken out full-page newspaper ads, as it did during the mad cow scare in Japan, reassuring consumers that its patties are made only with Australian beef.

In the United States, fast-food giant Chick-fil-A is taking it easy on its famously funny cow ads telling consumers to “eat mor chikin.” The chain has postponed unveiling its latest ad campaign to avoid appearing insensitive about mad cow disease concerns. The company says it is reviewing existing advertisements, including a billboard picturing a cow with its eyes in a vertigo swirl.

There have been no reports of danger from the meat processed from the sick cow. It all has been recalled, although some possibly tainted bones are known to have been used in the cooking process at five Vietnamese restaurants in California. Health officials maintain the risk to humans is very low, and say federal law prohibits disclosing the names of the restaurants.