Major events related to mad cow disease, or bovine spongiform encephalopathy (BSE):

--May 20, 2003: Scientists announce discovery of lone case of mad cow disease in Canada. U.S. health officials ban imports of cattle, beef, beef-based products and animal feed from Canada.

--Aug. 9: The United States announces it will resume imports of some Canadian boneless meat products and game animals by month's end.

--Sept. 11: Truckloads of Canadian beef cross U.S. border for first time since May.

--September: Cattle prices soar to highest levels in at least a decade, a result of drought, growing demand and Canada's case of mad cow disease.

--Dec. 23: Agriculture Secretary Ann Veneman announces first suspected appearance of mad cow disease in the United States. Japan and South Korea halt U.S. beef imports. Some 50 countries eventually follow, including Australia, Mexico and other Asian countries. Canada follows with a limited ban.

--Jan. 6, 2004: DNA tests confirm that cow diagnosed with first U.S. case of mad cow was born in Canada, U.S. officials say.

--Feb. 4: International panel convened by Veneman calls for more restrictions on cattle feed, saying there are probably undiscovered mad cow cases. The next day, Veneman says there still is no cause for alarm.

--Feb. 14: FDA panel recommends U.S. government step up testing for mad cow disease to evaluate any risk to American consumers.

--Feb. 19: Agriculture Department economist says U.S. beef bans imposed by more than 50 nations will push U.S. retail prices down 10 percent to 15 percent in the second half of the year.

March 3: USDA inspector general says government has begun a criminal investigation into whether records may have been falsified in the U.S. case of mad cow disease. Mexico partially lifts its ban on U.S. beef imports.

--March 15: Officials say USDA will expand its testing for mad cow disease to more than 221,000 animals over the next year to 18 months, 10 times the number tested in 2003.

--March 26: United States formally notifies trading partners that U.S. beef is safe to eat.

--June 1: USDA begins expanded national testing for mad cow disease.

--June 25: Agriculture officials say two animals in the United States tested inconclusive in a preliminary screening test for mad cow disease.

--June 30: Officials say follow-up tests showed no sign of mad cow disease in the animals.

--July 9: Government tells cosmetics makers they can no longer use brain and spinal cord tissue from older cattle in lipstick, hair sprays and other products.

--Oct. 23: U.S. and Japanese negotiators agree to ease a 10-month-old ban on U.S. beef exports to Japan. Agreement would allow resumption of Japanese beef exports to the United States.

--Oct. 26: Pending a final round of inspections, Taiwan agrees to resume U.S. beef imports.

--Nov. 18: Agriculture officials say they may have found a second case of mad cow disease in the United States.