Dear Editor,
We thank Jean Szkotnicki and the Canadian Animal Health Institute for their comments regarding our review article on broiler antimicrobial use published in the December 2012 issue (Can Vet J 2012;53:1289–1300). We agree that phasing out growth promotion claims for antimicrobials that may have implications for resistance and human health and implementation of a veterinary feed directive process would further enhance prudent use of antimicrobial drugs.
Currently, infeed and water dosage forms of veterinary drugs, including antimicrobial drugs, are available over-the-counter (OTC) and include those for administration in mass medication situations. In order to comply with the Feeds Regulations, all medicated feed manufactured or sold in Canada must be prepared in such a way as to adhere to the specifications of the Compendium of Medicating Ingredient Brochures (CMIB). The sole exception is feeds prepared according to a veterinarian’s prescription, considered extra-label drug use. In comparison, there is less oversight for the OTC veterinary drugs in dosage form for administration through water.
The paper largely focused on the 3 major diseases with clinical relevance to Canadian poultry; a thorough discussion on Canadian antimicrobial use practices that highlights current industry initiatives aimed to manage antimicrobial use and resistance may be described in future articles. Table 1 listed available antimicrobials (that is, as described by various authors for the therapy of diseases included in the review) and their current pattern of use, regardless of their on-label approval status in Canada. The actual use of these antimicrobials in the industry remains largely unknown but the implementation of the CIPARS national surveillance program for antimicrobial use and resistance in the broiler sector beginning 2013, in collaboration with the industry, will help quantify usage.
In terms of your request for additional data, we feel that CIPARS is well-positioned to provide much of this information: the CIPARS program targets selected indicator and zoonotic organisms from humans, animals, and foods of animal-origin and collects antimicrobial use information in humans and animals (http://www.phac-aspc.gc.ca/cipars-picra/index-eng.php). As concluded in our review, data gaps exist regarding antimicrobial use and resistance, though current surveillance findings demonstrate emerging/re-emerging trends in antimicrobial resistance concerning zoonotic organisms (for example, ceftio-fur-resistant Salmonella Heidelberg and ciprofloxacin resistant Campylobacter). The authors agree that more research and surveillance would further contribute to the understanding of the epidemiology of antimicrobial resistance, help quantify clinical outcomes, and close the data gaps in antimicrobial use and resistance.