For more than a year, a once-popular drug that makes cattle put on weight faster has been stuck in a kind of veterinary purgatory.
As far as the Food and Drug Administration is concerned, the drug, Zilmax, is legal to use. But large meat packers, which dominate the industry, have ostracized it after the drug was accused of making animals suffer. The drug's manufacturer, Merck, has been working on a plan to rehabilitate it. But that effort has stalled.
Merck suspended sales of Zilmax in August 2013, after Tyson, a leading beef processor, announced that it would no longer buy cattle that had been treated with Zilmax, and other cattle buyers followed Tyson's lead. Tyson's move followed reports that Zilmax-treated cattle were more likely to suffer from what some researchers call "cattle fatigue syndrome." At an industry conference, an animal welfare expert from the meat packer JBS showed a video of Zilmax-treated cattle that appeared immobile, unable to move properly.
Merck responded with a "five-step plan" to examine the safety of Zilmax. Last November, it unveiled new procedures for using the drug, including guidelines and training that are intended to prevent overdosing cattle with the drug.