A spokeswoman for Merck & Co said the drugmaker intended to sell Zilmax again in the US and Canada. Spokeswoman Pamela Eisele told Reuters by email that it would resume sales in both countries once the company had completed its audit on how the controversial animal feed additive is used. However, Eisele said it was still too early to tell when Zilmax would again be sold in the US and Canadian markets.

In August, Merck stopped selling the drug which could build muscle among cattle. The move to halt sales came after meat processing company Tyson Foods Inc said they would not accept Zilmax-feed beef anymore. This was prompted by observations that some cattle had difficulty walking as they arrived at the slaughterhouse. Tyson did not specifically name Zilmax as the cause of the animals' behavior. However, officials from the meat processing firm cited animal health experts who had suggested that the additive could be the cause of the cattle's behavior.