Antibiotic Use in the Feedlot:
A VET ’S PERSPECTIVE
D R . ST E V E H E N DRICK
Outline:
Antibiotic use in the feedlot
◦ Treatment vs. Prevention
Issues or Concerns
Questions and Comments
Antibiotic Use in Food Animals
Drugs approved for use by the federal government
◦ Clinical efficacy, human and animal safety, manufacturing
Prescribed by veterinarians according to the existing prudent use
guidelines
◦ Canada vs. US
Protocols guide there usage at the feedlot
◦ Computerized records
◦ Monitor compliance
Veterinary Drug Use in North America
Canada:
United States:
Veterinary Drugs Directorate
FDA (Food and Drug Administration)
◦ Branch of Health Canada
◦ Branch of USDA
◦ “Evaluates and monitors the safety, quality and
effectiveness, sets standards, and promotes the Animal Medicinal Drug Use
prudent use of veterinary drugs administered to Clarification Act (AMDUCA)
food-producing and companion animals”
◦ Extra-label drug use
◦ Licensure of drugs
Canadian Veterinary Medical Association
American Veterinary Medical
Association
Canadian Cattlemen’s Association
National Cattlemen’s Beef Association
Feedlot Antimicrobial Use
1. Treatment of sick animals
◦ Animal welfare implications  “natural beef”
◦ Bovine respiratory disease (BRD) and footrot (FR)
2. Prevention of disease
◦ Value in disease prevention
◦ Vaccination vs. Antimicrobials
◦ “Improved feed efficiency”
◦ Ionophores
◦ BRD metaphylaxis – “sick vs. home sick”
Metaphylaxis
Long-acting macrolides are commonly given upon entry to the feedlot
Do these antimicrobials allow for poorer management or buying
decisions?
◦ Ranch direct vs. Auction-derived fall placed calves
◦ Pen size commonly dictates mixing of cattle
◦ How and when were the calves weaned?
◦ Coaldale Vet Clinic Data: Calves vs. Yearlings
◦ Morbidity and mortality over the past 12 years
Fall Placed Calves - Morbidity
Total Morbidity
BRD Morbidity
FR Morbidity
n=500,000
70
60
50
40
30
20
10
0
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
Fall Placed Calves - Mortality
Total Mortality
Infectious Mortality
Digestive Mortality
3.0
2.5
2.0
1.5
1.0
0.5
0.0
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
Yearling - Morbidity
Total Morbidity
BRD Morbidity
n=1.6 million
FR Morbidity
20
18
16
14
12
10
8
6
4
2
0
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
Yearling - Mortality
Total Mortality
Infectious Mortality
Digestive Mortality
1.2
1.0
0.8
0.6
0.4
0.2
0.0
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
Preconditioning
Weaned, castrated, vaccinated and bunk started
Despite the value shown in several studies, its been hard to
implement on a broad scale
◦ Limited value to the rancher
◦ Structure of the industry
◦ Vertical integration or alliances
◦ Mandated through legislation
◦ Will the industry change?
Antimicrobial Resistance
Remains a significant concern to the beef industry
1.
2.
Safety of our beef
Efficacy of our treatments
◦ Welfare implications
Complex issue - many human, animal, bacterial and environmental factors
◦ Surveillance:
◦ Government - Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS)
◦ Resistance in zoonotic bacteria (farm to fork)
◦ Pharmaceutical industry
◦ Industry research
◦ Private clinics and feedlot clients
Science-based policy
Perception Issues… for the Food Animal Industries
1. Own use importation
◦ Harmonization of licenced products and prices in North America
◦ Limited importation of antimicrobials or active pharmaceutical ingredients (API’s )
2. “Growth Promotion” – feed antimicrobials
◦
Canadian Animal Health Institute – proposed label changes (Summer 2014)
3. “Over-the-counter sales” – purchase of antibiotics without a prescription
4. Vets prescribe and sell antimicrobials
◦ Conflict of interest
Health Canada
Category
Preferred option for
treatment of serious human
infections
No or limited
alternatives available
I – Very High Importance
Yes
Yes
II – High Importance
Yes
No
III – Medium Importance
No
No/Yes
IV – Low Importance
Not applicable
Not applicable
Category 1: Very High
1.2 Cephalosporins – the third and fourth generations – Excenel, Excenel RTU and Excede
1.3 Fluoroquinolones – Baytril and A-180
Category 2: High
2.2 Cephalosporins – first and second generations – mastitis formulations
2.5 Macrolides – Micotil, Draxxin, Zactran, Zuprevo
2.6 Penicillins
2.8 Streptogramins - virginiamycin
2.9 Trimethoprim/sulfamethoxazole – Borgal, Trivetrin
Metaphylaxis?
Category 3: Medium
3.6 Phenicols – Nuflor, Resflor
3.7 Sulphonamides – scour boluses
3.8 Tetracyclines – Biomycin, Liquamycin, Oxymycin, chlortetracycline, etc.
Category 4: Low
Not used in human medicine
4.2 Ionophores - Rumensin
Summary
Antimicrobials remain an important tool to the feedlot
◦ Treatment and prevention of disease
◦ Animal welfare implications
◦ Used according to prudent use guidelines
◦ Guidelines we currently use will change in time
◦ We need to start the conversation before its forced upon us
Many real and perceived concerns yet to be addressed
Questions or Comments