American Association of Swine Veterinarians
Basic Guidelines of Judicious Therapeutic Use of Antimicrobials
in Pork Production
(Approved by the AASV - October 2004)
Veterinarians agree to protect animal and public health when they
pledge the Veterinarian's Oath. This oath is applicable today as
it was when it was written many years ago. Swine practitioners are
committed to "the use of scientific knowledge and skills for
the benefit of society." This commitment remains the core of
veterinarians' efforts to achieve "the protection of animal
health, the relief of animal suffering, the conservation of livestock
resources, the promotion of public health, and the advancement of
medical knowledge."
Position Statement
When a condition exists that threatens or impairs animal health
and well being, it is essential that an accurate clinical diagnosis
be obtained. Appropriate diagnostic techniques and clinical experience
should substantiate a presumptive diagnosis. Once the decision is
reached to use antimicrobials for therapy, veterinarians strive
to optimize therapeutic efficacy, minimize resistance to antimicrobials,
and protect public and animal health.
The American Association of Swine Veterinarians supports and is
committed to the following objectives as developed by the American
Veterinary Medical Association's Steering Committee on Judicious
Therapeutic Antimicrobial Use:
• Support development of a scientific knowledge base
that provides the basis for judicious therapeutic antimicrobials
use.
• Support educational efforts that promote judicious
therapeutic antimicrobials use.
• Preserve therapeutic efficacy of antimicrobials.
• Ensure current and future availability of veterinary
antimicrobials.
Judicious Therapeutic Use of Antimicrobials Principles
for Swine Veterinarians
- Preventive strategies, such as appropriate husbandry
and hygiene, routine health monitoring, and immunization, should
be emphasized.
- Establish the definitive diagnosis.
- Recognize the roles played by the following factors in the
course of the disease(s):
- Genetics
- Genetic sources
- Genetic predisposition
- Nutrition
- Water availability and quality
- Protein
- Energy
- Micronutrients
- Housing
- Air space per pig
- Temperature extremes beyond the thermal comfort zone of
swine
- Meteorological conditions (e.g., seasonal patterns)
- Ventilation
- Management
- Stocking density
- Appropriate biosecurity controls of animals and humans
- Isolation and acclimatization of incoming breeding swine.
- Appropriate and timely use of cleaning, disinfection and
drying of premises.
- Depopulation/repopulation to eliminate a disease organism.
- Health
- Immune status of the animals
- Herd dynamics and health status of the sow herd
- Presence and importance of concurrent infections
- Source of pigs (e.g., single source or multiple sources
- Other therapeutic options should be considered prior
to or in conjunction with antimicrobial therapy.
- Examples include acidification of feed or water, electrolyte
therapy, supportive care (e.g., antipyretic therapy).
- Judicious use of antimicrobials, when under the direction
of a veterinarian, should meet all requirements of a veterinarian-client-patient
relationship.
- Antimicrobials represent a powerful therapeutic option. Specific
guidelines on the use of prescription antimicrobials and the
extralabel use of any antimicrobial must involve a VCPR. We
believe that judicious use requires the oversight of a veterinarian
at some point in the decision making process. (See glossary
for definition of VCPR as it appears in AMDUCA)
- Prescription, Veterinary Feed Directive, and extralabel
use of antimicrobials must meet all the requirements of a valid
veterinary-client-patient relationship.
- The law prohibits extra label use of antimicrobials in the
feed.
- Extralabel antimicrobial therapy must be prescribed
only in accordance with the Animal Medicinal Drug Use Clarification
Act amendments to the Food, Drug, and Cosmetic Act and its regulations.
- The following drugs are expressly prohibited for extralabel
use in food animals: chloramphenicol, clenbuteral, diethylstilbestrol,
dimetridazole, ipronidazole, other nitroimidazoles, furazolidone,
nitrofurazone, sulfonamide drugs in lactating dairy cows (except
approved use of sulfadimethoxine, sulfabromomethazine, and sulfaethoxypyridazine),
fluoroquinolones, glycopeptides (e.g., vancomycin), and phenylbutazone
in female dairy cattle 20 months of age or older. (Current as
of October 7, 2004 . Check for updates on the FDA web site at
www.fda.gov/cvm)
- For more information on extralabel drug use, see the AMDUCA
guidance brochure entitled Extralabel Drug Use (ELDU) ,
published by the AVMA.
- Veterinarians should work with those responsible for
the care of animals to use antimicrobials judiciously regardless
of distribution system through which the antimicrobial was obtained.
- Judicious use requires the oversight of a veterinarian at
some point in the decision making process.
- Veterinarians are the primary source of information on the
use of swine antimicrobials.
- Veterinarians must accurately communicate written, adequate
directions to the client for antimicrobial use.
- The Pork Quality Assurance (PQA) program of the National Pork
Board provides a basis for the judicious use of antimicrobials.
- The AASV recognizes the legal availability of antimicrobials
obtained through over-the-counter (OTC) distribution channels.
- The extra label uses of OTC antimicrobials fall within the
regulatory constraints of the Animal Medicinal Drug Use Clarification
Act and thus requires the oversight of a veterinarian.
- Regimens for therapeutic antimicrobial use should be
optimized using current pharmacological information and principles.
- Package inserts should be considered as sources of information
for the practitioner.
- Continuing education is an important component of maintaining
and enhancing the veterinarian's pharmacological knowledge.
- AASV supports the development of a veterinary antimicrobial
decision system for swine to improve accuracy in the selection
of therapeutics.
- The compounding of antimicrobials should be avoided in those
instances where there is a lack of supporting scientific pharmacological
data.
- Combinations that do not currently have FDA approval should
not be used in the absence of supporting scientific pharmacological
data.
- Cost is not a factor when considering the use of compounded
therapeutic antimicrobials.
- For more information on compounding, see the FDA Compliance
Policy Guide entitled Compounding of Drugs for Use in Animals
.
- Antimicrobials considered important in treating refractory
infections in human or veterinary medicine should be used in animals
only after careful review and reasonable justification. Consider
using other antimicrobials for initial therapy. (1)
- Utilize culture and susceptibility results to aid in
the selection of antimicrobials when clinically relevant.
- Clinical outcomes, history, and experience should also be
used in the selection of antimicrobials.
- Veterinarians should utilize appropriate references for proper
procedures and accurate interpretation of susceptibility results,
such as the NCCLS publication, Performance Standards for
Antimicrobial Disk and Dilution Susceptibility Tests for Bacteria
Isolated from Animals; Approved Standard .
- Therapeutic antimicrobial use should be confined to
appropriate clinical indications.
- An accurate diagnosis includes characterization of etiology.
- Practitioners should strive to rule out parasitisms, mycotoxicoses,
nutritional imbalances, and viral infections.
- Secondary bacterial pathogens may require antimicrobial therapy.
- Therapeutic exposure to antimicrobials should be minimized
by treating only for as long as needed for the desired clinical
response.
- Therapeutic exposure involves both dose and duration.
- Continued use of antimicrobials in chronic, non-responsive
clinical cases should be discouraged.
- Withdrawal times must always be considered during the selection
of antimicrobials.
- Limit therapeutic antimicrobial treatment to ill or
at risk animals, treating the fewest animals indicated.
- Consider group morbidity and mortality rates when deciding
whether or not to initiate herd, group, or individual therapy.
- Consider the herd health history for the therapeutic use of
antimicrobials in the control and prevention of disease.
- When these factors are appropriately considered, preventative
therapy is a judicious use of antimicrobials.
- Minimize environmental contamination with antimicrobials
whenever possible.
- Water medicators and feeders need to be properly adjusted
to deliver the desired dose and to avoid spillage and waste.
- Accurate records of treatment and outcome should be
used to evaluate therapeutic regimens.
- AASV recommends the use of treatment records such as those
proposed by the Pork Quality Assurance (PQA) program of the
National Pork Board.
- Compliance to treatment regimens can be monitored by the review
of pertinent records.
- Accurate animal or group identification must be employed within
a production system for effective residue avoidance.
(1) In this context, this principle takes into account development
of resistance or cross-resistance to important antimicrobials.
Glossary:
Antibiotic --a chemical substance produced by a
microorganism which has the capacity, in dilute solutions, to inhibit
the growth of or to kill other microorganisms.
Antimicrobial --an agent that kills bacteria or
suppresses their multiplication or growth. This includes antibiotics
and synthetic agents. This excludes ionophores and arsenicals.
Narrow Spectrum Antimicrobial --an antimicrobial
effective against a limited number of bacterial genera; often applied
to an antimicrobial active against either Gram-positive or Gram-negative
bacteria.
Broad Spectrum Antimicrobial --an antimicrobial
effective against a large number of bacterial genera; generally
describes antibiotics effective against both Gram-positive and Gram-negative
bacteria.
Antibiotic Resistance --a property of bacteria
that confers the capacity to inactivate or exclude antibiotics or
a mechanism that blocks the inhibitory or killing effects of antibiotics.
Extralabel --Extralabel use means actual use or
intended use of a drug in an animal in a manner that is not in accordance
with the approved labeling. This includes, but is not limited to,
use in species not listed in the labeling, use for indications (disease
or other conditions) not listed in the labeling, use at dosage levels,
frequencies, or routes of administration other than those stated
in the labeling, and deviation from the labeled withdrawal time
based on these different uses.
Immunization --the process of rendering a subject
immune or of becoming immune, either by conventional vaccination
or exposure.
Monitoring --monitoring includes periodic health
surveillance of the population or individual animal examination.
Therapeutic --treatment, control, and prevention
of bacterial disease.
Veterinarian/Client/Patient Relationship (VCPR) -- A VCPR exists
when all of the following conditions have been met:
- The veterinarian has assumed the responsibility for making clinical
judgements regarding the health of the animal(s) and the need
for medical treatment, and the client has agreed to follow the
veterinarian's instructions.
- The veterinarian has sufficient knowledge of the animal(s) to
initiate at least a general or preliminary diagnosis of the medical
condition of the animal(s). This means that the veterinarian has
recently seen and is personally acquainted with the keeping and
care of the animal(s) by virtue of an examination of the animal(s)
or by medically appropriate and timely visits to the premises
where the animal(s) are kept.
- The veterinarian is readily available for follow-up evaluation,
or has arranged for emergency coverage, in the event of adverse
reactions or failure of the treatment regimen.
Veterinary Feed Directive (VFD) Drug --The VFD
category of medicated feeds was created by the Animal Drug Availability
Act of 1996 to provide an alternative to prescription status for
certain therapeutic animal pharmaceuticals for use in feed. Any
animal feed bearing or containing a VFD drug shall be fed to animals
only by or upon a lawful VFD issued by a licensed veterinarian in
the course of the veterinarian's professional practice.
