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Antimicrobial Use in Veterinary Medicine

Today and Tomorrow...

W. Ron DeHaven, DVM, MBAExecutive Vice President and CEOAmerican Veterinary Medical Association

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Definitions

MicroorganismsAntimicrobialsAntibioticsAntimicrobial Resistance

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Uses of Antibiotics

Treatment Control Prevention Production Uses

(Growth Promotion/Feed Efficiency)

Animal uses currently approved by FDA

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Sources and Regulatory Oversight of Antimicrobials

Over-the-Counter (OTC) Producers, only as approved on label; can be feed or water Added to feed by a feed mill or producer as directed on the

FDA approved label Veterinary Feed Directive (VFD)

Currently only 2 drugs are approved - florfenicol (Nuflor) and tilmicosin (Pulmotil)

OTC => VFD medically important antimicrobials in feed Prescription (Rx) –

GFI 213 transitions medically important antimicrobials in water from OTC to Rx and allows mechanism to seek therapeutic claims for production use antimicrobials

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Differences in Use

Human Medicine For treatment or prevention Physician determines indication and route of administration,

dose, frequency, and duration of treatment No restrictions on extra-label or "off label" uses

Food Animals Drug only approved for specific indications, e.g., respiratory

disease due to Pasteurella multocida Only allowed at specific dosage, duration, frequency, and

route of administration Extra label uses heavily regulated

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A Source of Controversy…

Antimicrobial use in food producing animals can serve as a reservoir for antimicrobial resistance, i.e., the more we expose the organisms to antimicrobials the more we give them the opportunity to develop resistance.

Although that may be true in a very simplified, general sense, there is no clear scientific evidence of how, and to what extent such exposure affects human health.

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Additional Complexity

While plausible, there is no hard evidence that cases of human infection with a resistant bacteria have been caused by use of antimicrobials in food animals.

There is little to no evidence that restricting or eliminating the use of antimicrobials in food-producing animals would improve human health or reduce the risk of antimicrobial resistance to humans.

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Benefits vs. Risk

Benefits of AntibioticsAnimal welfare

Prevent, control, & treat diseaseFood safety

Healthy animals produce safer foodEconomic - EfficiencyEnvironmental

Disadvantages Antimicrobial resistant bacteria can develop

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Impact of Animal Health on Foodborne Risk

Healthy: Passed FSIS antemortem inspection (not visibly ill)

Some (~7%) had internal adhesions from previous chronic infectionCarcasses 90% more likely to be contaminated with Salmonella

Photo credit: Hudson ISD FFA

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Which is Preferred?

Less Use vs. More UseLower dose in more animals (today)Higher dose in fewer animals (tomorrow?)

Stronger drugs? Or more culls?

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Differing Approaches

Discontinue Use Although we may not know the degree of risk, why

should we take any chances? Let’s eliminate or reduce the use of antibiotics in animals

on the possibility that this is jeopardizing human health.

Continue Use Let’s not take any action that is not based on a scientific

risk assessment. The benefits to animal health, welfare, and food safety

outweigh the risks to human health based on risk assessments done to date.

Novel Approach ?

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We Need a Collaborative Approach!

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AVMA's Current Approach

Judicious use of antimicrobialsMaximize benefit, minimize risks

Supports veterinary involvement in any use of antimicrobials

Actions to limit use should be based on: Available scientific researchRisk-based assessments

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Preservation of Antibiotics for Medical Treatment Act (PAMTA)

Purpose Preserve the effectiveness of medically important antibiotics used in

the treatment of human and animal diseases by reviewing the safety of certain antibiotics for nontherapeutic purposes in food-producing animals.

Nontherapeutic Use Use of the drug as a feed or water additive for an animal in the

absence of any clinical sign of disease in the animal for growth promotion, feed efficiency, weight gain, routine disease prevention, or other routine purpose.

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AVMA’s Position on PAMTA

Not supported by science (based on AVMA’s interpretation)

Lacks risk-based assessments Has potential to eliminate 2 or 3 of the 4

approved uses of antibiotics in animals Animal welfare implications

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Greater Veterinary Oversight

Some believe this is the way to go – supported by market research

General agreement within AVMA (We think!) Workforce shortage issue (some disagree) VFD is primary vehicle for greater oversight in

antimicrobials in feed Degree of oversight proportionate to risk AVMA would do all we can to make it work!

Veterinary Oversight Steering Committee

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Legislation versus Regulation

Legislation Less opportunity for scientific input & evaluationCan be more politically motivated

Regulation (rulemaking process)Provides months/years for inputMore of a deliberative processStatutory authority already exists

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FDA-CVM Perspective

Innovative use of VFD Supportive of and recognition of the importance of

treatment, control, and prevention Phase in greater veterinary oversight Phase out growth promotion/feed efficiency

Data needed – Is Growth Promotion really prevention?

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So, where are we headed?

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Pathogenesis of Baldness

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So, where are we headed?

More Veterinary OversightWorkforce concernsMore responsibility and more credit - yet also

more blame Role of Veterinarians? Huge!

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