—By Tom Philpott| Fri Apr. 27, 2012

RuffLife/Flickr

Move along, nothing to see here.

That sums up the USDA's public reaction to news that a downed California dairy cow was discovered to have contracted bovine spongiform encephalopathy, also known as mad cow disease. The cow had an "atypical" case of BSE, one that likely doesn't come from BSE-infected feed, but rather from a genetic mutation, the agency insists.

Moreover, it never came close to entering the food supply, USDA stressed—it had shown up dead at a rendering facility, where it was randomly chosen for testing as part of the USDA's BSE-testing program. USDA chief Tom Vilsack, ever ready to jump to the meat industry's aid at a time of need, declared on CNN, "I'm having beef tonight for dinner. And that's no lie."

Global food and health agencies echoed the USDA's assessment, Bloomberg reports: "The U.S. finding of a case of mad cow disease shows the country’s surveillance system is working, according to the United Nations' Food & Agriculture Organization and the World Organisation for Animal Health."

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Let me raise two uncomfortable points about this case.

• The idea that the discovery of this BSE-stricken cow proves that the US "surveillance system is working" is, well, ludicrous. The cow showed up at Baker Commodities, a California company plant that buys spent cows from California's vast dairy industry and renders them into various pet and livestock feed products.

Here's how a Baker executive described the discovery to Business Week:

"We randomly pick a number of samples throughout the year, and this just happened to be one that we randomly sampled," Baker Commodities executive vice president Dennis Luckey said. "It showed no signs" of disease.

So when the rendering plant picked up the infected cow, it was just another dead cow to be rendered. However, in an update released Thursday afternoon, the USDA revealed that the animal was "humanely euthanized" on the dairy farm where it lived, "after it developed lameness and became recumbent." Apparently, the dairy farm did not communicate with the rendering plant that the cow had gone lame, and thus was a good candidate for BSE infection.

Altogether, the USDA program tests about 40,000 cows a year for mad cow—a tiny fraction of the millions that are slaughtered or otherwise die each year. (Bloomberg puts the portion tested annually at "less than 0.1 percent of the U.S. cattle herd.") By contrast, in the European Union, all sick or downed cattle over the age of 4 years old, all healthy cows over six years, are tested before being slaughtered or rendered. The California cow, the USDA said in its Thursday statement, was 10 years and seven months old—so it would have been automatically tested in Europe.

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