Exclusive: FDA says working with Merck, USDA on cattle drug Zilmax

The U.S. Food and Drug Administration on Friday said it was working with drugmaker Merck & Co and the U.S. Department of Agriculture to gather information on the cattle feed additive Zilmax and determine if it poses a safety issue.

The FDA, in an email response to a Reuters query, said it had received "a very small number of reports of lameness or lying down" in cattle whose feed contained zilpaterol, or Zilmax. The agency said it would review any new information about the additive and would notify Merck and the public if it established that the product posed safety concerns.

"We are always interested in new information about the safety and effectiveness of approved animal drugs," the FDA statement said. The agency does not typically reveal its investigations.

Merck on Friday said it was temporarily suspending sales of Zilmax due to concerns about the product, which is given to cattle to increase their weight before slaughter.

(Reporting by Alina Selyukh; Editing by John Wallace)