A routine test indicated the possible presence of mad cow disease. U-S-D-A official John Clifford says inconclusive results are a normal part of the extremely sensitive tests. He says it does not necessarily mean a new case has been found. More detailed tests are being done in a lab in Iowa. Results are expected in four to seven days. Clifford says the cow did not enter the human or animal food chain. U-S-D-A won't say where the animal was from. IIn humans, eating meat products contaminated with mad cow disease has been linked to more than 150 deaths worldwide from a rare and fatal nerve disease. A majority of the deaths were in Britain, where there was an outbreak of mad cow disease that started in the mid-1980s.