US food safety authorities on Thursday called a new case of mad cow disease in California "atypical" and said they were confident in measures to prevent the disease from spreading via animal feed.
The Food and Drug Administration sought to tamp down fears that the new case of bovine spongiform encephalopathy (BSE) that surfaced Tuesday could herald a broader outbreak and disrupt the country's huge trade in livestock and beef.
"The FDA is confident in the effectiveness of the existing animal feed safeguards designed to prevent the spread of BSE through feed," they said in a statement.
"Although current science suggests that atypical cases of BSE, such as this one, are unlikely to be transmitted through animal feed, the FDA will work with the USDA (the Department of Agriculture) to complete a thorough epidemiological investigation."
Some previous cases of mad cow disease have been tied to the use of cattle remains in feed for livestock.
Incidents of the disease in the United States, Canada, Israel, Europe and Japan have caused disruptions to the global food trade worth billions of dollars.
The FDA also sought to calm consumer worries over beef and milk sold in markets.
"The USDA also confirmed the cow did not enter the animal feed or human food supply," the statement said.
"Importantly, scientific research indicates that BSE cannot be transmitted in cow's milk."
"The FDA is committed to protecting the safety of the US human food and animal feed supply from BSE," it added.