The approval of drugs is a federal responsibility. It is done through Health Canada and monitored partly by CFIA. The use of antimicrobial drugs is a provincial responsibility, through the veterinary acts or livestock medicines acts.
There's this federal-provincial crack, which means, for example, with the ceftiofur story, if you wish to say you can't use ceftiofur extra labelling for injecting chickens, the only thing you can do federally is put a warning label on saying there may be problems of resistance. But there's no way currently under the regulations to say you cannot use ceftiofur extra label for injection of chicks, let's say. There's no way to do it.