In mid-February the U.S. government gave up on its search for the herd mates of the first known U.S. case of bovine spongiform encephalopathy (BSE), popularly known as mad cow disease. The end of the trace-back effort, which began after the sick animal was uncovered in December 2003, means that the whereabouts and disposition of 52 of the 81 cattle that entered the country with the infected cow from Canada will remain uncertain. Of those 52, 11 were born at about the same time as the BSE cow and may have eaten the same contaminated feed that is presumed to have been the vector for the sickness.

The problem lies with the antiquated method of keeping tabs on animals--important not just for BSE but for other illnesses among livestock, such as foot-and-mouth disease, and for food poisoning resulting from Escherichia coli or Salmonella contamination. Unlike Canada, the U.K., the European Union and Australia, the U.S. does not mandate livestock tracking nationally. Moreover, there are significant regional differences in how animals are handled. Reliance on paper records contributes to slowness and inefficiency. And because only sick animals and their herd mates are followed, success in wiping out some livestock diseases (such as brucellosis) has, ironically, acted in the past few years to reduce the number of animals being tracked.

This article was originally published with the title Missing Movement.

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