NEW RESEARCH: Surveillance of antimicrobial use and resistance to improve stewardship practices and animal health on dairy farms

The increase in antimicrobial resistance in dairy cattle could have adverse effects on animal health and welfare, impacting the profitability of dairy farms. About 48% of antibiotics prescribed to a dairy farm are to treat mastitis infections in cattle.[i] While most mastitis pathogens are low in antimicrobial resistance, choosing and using other antimicrobials to treat dairy cattle health can result in the transfer of antimicrobial resistance in bacteria other than mastitis pathogens.

Researchers are developing a surveillance program to measure antimicrobial use (AMU) and antimicrobial resistance (AMR) on Canadian dairy farms, as well as the effectiveness of antimicrobial stewardship protocols and programs. Led by researchers Javier Sanchez and Luke Heider (University of Prince Edward Island) with collaborators from across Canada, the team is collecting data and information to help support farmers’ efforts in applying effective antimicrobial stewardship practices.

The pan-Canadian team has developed a platform to collect data and monitor AMU and AMR. The Canadian Dairy Network of Antimicrobial Stewardship and Resistance (CaDNetASR) is a first for the dairy sector and designed to conform with the Federal Action Plan on Antimicrobial Resistance and Use in Canada, and the Food Safety and Biosecurity modules of proAction®. Data is being collected on about 150 dairy farms in British Columbia, Alberta, Ontario, Quebec, Nova Scotia and New Brunswick on a yearly basis.

“The network has been very active since the funding of the project and even under the Covid-19 situation, we are completing the second year of data collection. We’re focused on two major activities in the network. The first is the harmonization of veterinary clinic dispensing records to quantify the use of the antimicrobials in each of the participating farms. This is being conducted with the active participation of veterinary clinics representing the study farms. The second activity is the development of intervention strategies to assess their impact on mastitis, cow health and animal welfare. In addition, we are finalizing the data management system that will allow the generation of reports to send back to producers with their antimicrobial usage and antimicrobial resistance profiles compared to the other study farms.”

Javier Sanchez, co-lead of the project.

To provide antimicrobial use data estimates, treatment records logged as part of the Food Safety and Biosecurity modules of proAction®, and the retrieval of receptacles placed on farms for the deposit of empty drug bottles and containers are being used. To measure antimicrobial resistance on dairy farms, fecal, environmental and bulk tank milk samples are being taken and analyzed. The information will serve as a base for the development and testing of evidence-based and effective tools for farmers and their veterinarians (i.e. standard operating protocols or SOPs). 

“CaDNetASR has also developed a repository of bacterial isolates that, along with the other data being generated, will allow for future analysis and studies on AMU and AMR on Canadian dairy farms.”

Luke Heider, co-lead of the project.

The project outcomes will support farmers in continuing to use antimicrobials responsibly, apply efficient antimicrobial stewardship practices and assure the continued health and welfare of dairy animals and the safety of food for consumers. 

SEVEN facts about antibiotic use and antimicrobial resistance in the Canadian dairy sector

1.   Under proAction®, milk is produced according to strict provincial and federal regulations and high standards regarding antibiotic use to treat sick animals. proAction milk quality and food safety standards are among the highest in the world. 

2.   Dairy farmers use antibiotics to treat sick animals if necessary and as directed on the prescribed medication label and directives given by the herd’s veterinarian.

3.   Canadian milk is free of antibiotics. Cows treated with antibiotics for a medical reason are clearly identified, and the milk is discarded. The milk does not re-enter the system until the mandatory withdrawal time has been met to ensure the medication is out of the animal’s system.

4.   All milk is tested for antibiotic residues at the time it is picked up from a farm and again when it reaches the processing plant to guarantee it is antibiotic-free.

5.   Antibiotic resistance happens when bacteria change and become resistant to the antibiotics used to treat the infections they cause. (ii)

6.   Antimicrobial resistance development in major pathogenic bacteria found in dairy cows does not yet appear to be a major problem in North America (iii). Most antibiotic treatments are to treat mastitis, and the levels of antimicrobial resistance remain low in mastitis pathogens (iv-vi). But, the pressures to select and use antimicrobials to treat animals more rapidly for better health can result in the emergence and transfer of bacteria that are resistant (iii). 

7.   Disease prevention is key in a strategy to reduce antimicrobial use and resistance!

You can access the project summary by clicking on the link here: Surveillance of antimicrobial use and resistance to improve stewardship practices and animal health on dairy farms


Project Overview

Principal Investigators: Javier Sanchez and Luke Heider (University of Prince Edward Island) 

Co-Investigators: J Trenton McClure, Greg Keefe (University of Prince Edward Island), David Leger (Public Health Agency of Canada), Simon Dufour (Université de Montréal), Herman Barkema (University of Calgary), David Kelton (University of Guelph), Christopher Luby (University of Saskatchewan), and Kapil Tahlan (Memorial University of Newfoundland)

Collaborators: Marie Archambault, David Francoz, André Ravel, Jean-Phillipe Roy (Université de Montréal), Jeroen De Buck (University of Calgary), Scott McEwen, Jan Sargeant, Scott Weese (University of Guelph), Cheryl Waldner (University of Saskatchewan), Richard Reid Smith (Public Health Agency of Canada), 

Project duration: 2018-2022 

Project partners: Agriculture and Agri-Food Canada, Dairy Farmers of Canada and the Public Health Agency of Canada

TOTAL BUDGET: $1,582,087


i Adapted from: Bauman CA et al. Canadian National Dairy Study: Herd-level milk quality. J Dairy Sci. 2018 Mar;101(3):2679‍-‍2691.

ii World Health Organization, Antibiotic Resistance – How it Spreads, www.who.int/drugresistance

iii Oliver SP et al. Impact of antibiotic use in adult dairy cows on antimicrobial resistance of veterinary and human pathogens. Foodborne Pathog Dis; 2016; 8(3):337–55. 

iv Call DR et al. Antimicrobial resistance in beef and dairy cattle production. Anim Health Res Rev. 2008; 9(2):159–67. 

v Bengtsson B et al. Antimicrobial susceptibility of udder pathogens from cases of acute clinical mastitis in dairy cows. Vet Microbiol. 2009; 136(1–2):142–9.

vi Cameron M et al. Antimicrobial susceptibility patterns of environmental streptococci recovered from bovine milk samples in the Maritime provinces of Canada. Front Vet Sci. 2016; 3(79).

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