Veterinary medicines are widely used to treat disease and protect the health of animals. Dietary enhancing feed additives may also be incorporated into the feed of animals to improve their growth rates. Because of historic, measurable impacts in the environment, a number of groups of veterinary medicines (i.e. sheep dip chemicals, fish farm medicines and anthelmintics) are known to be of environmental concern. However, the environmental fate, behaviour and effects of other veterinary medicines and their potential environmental impacts are less well understood.