AAAP-AVMA Guidelines for Judicious Therapeutic Use of Antimicrobials in Poultry

Comment on this policyThe Principles of Judicious Therapeutic Use of Antimicrobials of the AVMA are the framework for the Guidelines for Judicious Therapeutic Use of Antimicrobials in Poultry of the American Association of Avian Pathologists. The purpose of this document is to provide information for field veterinarians on intervention strategies for common bacterial diseases of chickens and turkeys. This working document will be updated as needed by the American Association of Avian Pathologists Committee on Drugs and Therapeutics and the Committee on Food Safety with input by the National Chicken Council and the National Turkey Federation.

The overarching goals of veterinary poultry practice are to address the health and wellness of poultry. When the decision is reached to use antimicrobials, veterinarians should strive to optimize therapeutic efficacy and minimize resistance to antimicrobials to protect public and animal health. Use of antimicrobials can be minimized through carefully planned and executed preventative practices, including vaccination programs, automated ventilation controls, and conventional poultry husbandry and management programs. These programs are the pillars of sound production practices, and antimicrobial therapy provides an important tool aiding veterinarians in maintaining animal health and welfare.

Disease Prevention and Diagnosis
To ensure proper use of antimicrobials in poultry, focus should be placed on disease prevention strategies. The poultry environment should be managed to reduce morbidity and mortality rates. The birds’ environment should be optimized at all times, including thorough cleaning and disinfection of houses after a flock is removed. House environmental conditions should be altered frequently and as needed based on the appearance and activity of the birds. Noninfectious factors that predispose birds to disease include chilling, heat stress, inappropriate humidity, high ammonia concentrations, and unpalatable or unsanitary feed or water. Ventilation must be managed to minimize the negative impact from ammonia, dust, excessive humidity, or combustion gases on primary defense mechanisms in the birds. Likewise, ventilation should be optimized for litter moisture control to reduce bacterial exposure and control ammonia concentrations. To assess the progression of disease within a flock, removal of morbid birds may be required. Diagnostic testing and troubleshooting procedures should be initiated to identify the primary microbial challenge and any predisposing conditions. Strict biosecurity should be maintained to prevent spread to other houses on the same farm, and immunization should be used when warranted.

Therapeutic Antimicrobials Available for Use in Poultry
The classes of antimicrobials (animal drugs given for the treatment, control, or prevention of confirmed bacterial disease and administered through feed, water, or injection) that are currently approved by the FDA for use in poultry are summarized (Tables 1 and 2).

Judicious Antimicrobial Use
Antimicrobials may be administered in feed only in accordance with label instructions. For administration via water or injection, extralabel use may be additionally permitted if the federally codified valid veterinarian-client-patient relationship is established. Only after the valid  veterinarian-client-patient relationship is established and flock and farm history and diagnostic procedures are performed is extralabel drug use permitted. The use of medically important antimicrobials (Table 3) in animals is intended for therapeutic purposes at therapeutic dosages and under the supervision of a veterinarian. Products should be administered according to the manufacturer’s labeled recommendations or based on the clinical experience of the attending veterinarian. When multiple barns are present on the farm with disease, each flock within each barn should be evaluated individually for current disease status and risk of disease exposure. Only barns with clinically affected birds or those judged to be at definite risk should be treated. Morbidity and mortality rates should be evaluated closely to determine the treatment protocols. The least number of diseased and at-risk birds should be treated on a farm. Additionally, management, biosecurity, and vaccination programs should be reevaluated and corrective actions taken as necessary.

The following are general guidelines to aid veterinarians in making informed decisions regarding antimicrobial use:
  • Use according to labeled instructions should be considered first, if farm history, results of in vitro antimicrobial susceptibility testing, and clinical judgment warrant.
  • Extralabel drug use of antimicrobials administered via drinking water or injection may be considered if labeled use of antimicrobials in the same class have failed, if farm history or in vitro antimicrobial susceptibility testing dictates, or based on clinical experience of the attending veterinarian. Extralabel drug use must be within the context of a valid veterinarian-client-patient relationship (see the Principles of Judicious Therapeutic Use of Antimicrobials of the AVMA before initiating extralabel use).
  • When farm history, results of in vitro antimicrobial susceptibility testing, or clinical judgment warrants the use of highly important antimicrobials, their use should be in accordance with labeled instructions before extralabel use is considered. Antimicrobial choice should be dictated by potency and site-of-infection drug concentrations derived from pharmacokinetic and pharmacodynamic data if available, with extended withdrawal periods as appropriate.
  • Use of critically important antimicrobials should be considered as a last resort based on all appropriate information after antimicrobials classified as important or highly important have been carefully considered and all other intervention strategies have failed.
  • With any therapeutic regimen of important or highly important antimicrobials, use of narrow-spectrum antimicrobials is recommended to avoid overuse of broad-spectrum antimicrobials.
  • Bacteriostatic drugs should be considered cautiously when treating chronic infection due to decreased primary defense mechanisms in the birds. Overall effectiveness of bacteriostatic drugs in chronic infections may be decreased. Likewise, when immunosuppressive agents such as infectious bursal disease and chicken anemia virus are involved, bacteriostatic antimicrobials may not be clinically effective.

Antimicrobial Therapeutics Administered Via Water
Antimicrobial therapy can be administered via drinking water. Addition of ammonia to raise the pH of water may increase the solubility of some antimicrobials, such as sulfonamides and penicillin. Addition of organic or inorganic acid to lower water pH may increase the solubility of some classes of antimicrobials (eg, tetracyclines and erythromycin) when used via water application. In all cases, federal and state laws must be followed. For more information on compounding, visit the AVMA website. Any combination of antimicrobials would be subject to extralabel drug use rules as described in 21 CFR 530.13 (extralabel use from compounding of approved new animal and approved human drugs).

Feed-Grade Antimicrobial Therapeutics
Poultry veterinarians have the option to administer in-feed medications. Combinations of FDA-approved in-feed medications that have obtained cross-clearance are limited. However, if in-feed antimicrobials are considered, the appropriate feed-grade antimicrobial must be used per the FDA-approved label indication. Extralabel drug use of in-feed antimicrobials is not permitted under any commercial conditions.

Veterinarians are limited in their use of therapeutic antimicrobials in-feed based on FDA regulations published in the Code of Federal Regulations (21 CFR) and veterinary feed directive drugs section of the Animal Drug Availability Act of 1996. On December 11, 2013, the FDA finalized Guidance for Industry #213, establishing procedures for phasing out growth promotion indications for medically important antimicrobials in alignment with Guidance for Industry #209 and proposed changes to VFD drug regulations. The FDA CVM will assess progress made by drug sponsors after a 3-year period. All feed-grade antimicrobials may continue to be used as they are currently, at least until that time. The VFD regulation mandates the rules and responsibilities of licensed veterinarians in prescribing and administering medically important antimicrobials in feed. Guidance for Industry #209 establishes 2  principles: use of medically important antimicrobial drugs in food-producing animals should be limited to uses considered necessary for assuring animal health and use of medically important antimicrobial drugs in food-producing animals should include veterinary oversight or consultation. This would mean a change from over-the-counter to VFD regulation status for medicated feed products containing medically important antimicrobial drugs. Veterinarians should be involved in decisions regarding antimicrobial use in food animals for the health of the animal. No poultry in-feed medications currently require a VFD. Use of all medicated feed articles and combinations in poultry require following the FDA-approved label completely as extralabel drug use is not permitted. Veterinarians can refer to specific disease therapeutic strategies in this document to assess the potential benefit of approved feed-grade antimicrobials.

Injectable Antimicrobial Therapeutics
Injectable antimicrobials are used predominately at 1 day of age or in ovo to control omphalitis in chicks and poults. In ovo administration to prevent infection when the yolk is withdrawn into the body cavity can be an important intervention strategy to control early bacterial contamination. However, appropriate sanitation and temperature controls must be maintained from breeder farm through the hatchery to minimize of the need for antimicrobials at 1 day of age and in ovo. Injection strategies should be used to support ongoing hatchery sanitation and proper egg collection techniques and not in lieu of these procedures. Current antimicrobials cleared for use in 1-day-old chicks or poults are not approved for use in ovo, and therefore, extralabel drug use regulations must be followed. The use of cephalosporins at unapproved dosages, frequencies, durations or routes of administration) is prohibited; therefore, in ovo use in chickens and turkeys is no longer permitted.

Injectable antimicrobials are occasionally used in an extralabel manner, except for the cephalosporin class, for acute disease outbreaks in valuable and long-lived poultry. Fowl cholera and erysipelas can be treated in this manner. Antimicrobials used in this manner include long-acting oxytetracycline, florfenicol, and penicillin. With any such extralabel administration,  extralabel drug use regulations must be followed.

Further Reading
For further details on treatment of specific disease in poultry, please refer to references below.

  • Boulianne M, Brash ML, Charlton, BR, et al, eds. Avian disease manual. 7th ed. Jacksonville, Fla: American Association of Avian Pathologists, 2013.
  • Swayne DE, Glisson JR, McDougald LR, et al, eds. Diseases of poultry. 13th ed. Hoboken, NJ: Wiley-Blackwell, 2013.

For a complete and current list of all the products affected by Guidance for Industry No. 213 and VFD drug regulations refer to the CVM's website. This is a public document.  The VFD regulations and Guidance for Industry No. 213 were published in the Federal Register on December 12, 2013.  The original listing of medically important antimicrobials can be found in Appendix A of Guidance for Industry No. 152 but is now superceded by Guidance for Industry No. 213.

 

Table 1 - Classes of antimicrobials approved for use in poultry

Class​ Drug or Combination​

Aminoglycosides

Streptomycin
​Gentamicin
​Neomycin
​Aminocyclitols ​Spectinomycin
​Cephalosporins ​Ceftiofur
Decapeptides ​Bacitracin
​Lincosamides ​Lincomycin
​Macrolides ​Erythromycin tylosin
​Penicillins ​Potassium penicillin G
​Sulfonamides ​Sulfadimethoxine
​Sulfaquinoxaline
​Sulfamethazine
​Sulfamerazine, sulfamethazine,sulfaquinoxaline
​Tetracyclines ​Chlortetracycline
​Oxytetracycline
​Tetracycline hydrochloride
​Combinations ​Lincomycin-spectinomycin
​Sulfadimethoxine-ormetoprim

 
Table 2 - Classification of poultry antimicrobials approved for use in poultry, by human medical importance (FDA CVM Guidance for Industry No. 152)

​Critically Important ​Highly Important

Cephalosporins

​Penicillin

​Tylosin

​Virginiamycin

​Sulfadimethoxine-ormetoprim

​Tetracycline
​Tetracycline
​Oxytetracycline
​Lincomycin
​Neomycin
 

Table 3 - Medically important antimicrobials based on FDA CVM Guidance for Industry No. 152 (now superceded by Guidance for Industry No. 213) and also delineated by the medical importance classification of antimicrobial products in regard to their human medical importance.

​Critically Important Highly Important​​ Important
​Third-generation cephalosporins ​Natural penicillins ​First-generation cephalosporins
​Flouroquinolones ​Penase-resistant penicillins ​Second-generation cephalosporins
​Macrolides ​Antipseudomonal penicillins ​Cephamycins
​Trimethoprim-sulfamethoxazole ​Aminopenicillins ​Monobactams
​Fourth-generation cephalosporins ​Quinolones
​Carbapenems
​Aminoglycosides
​Clindamycin
​Tetracyclines
​Glycopeptides
​Streptogramins
​Oxazolidones
​Pyrazinamide
Isoniazid
​Rifamycins
Chloramphenicol​
​Metronidazile
​Metronidazile
 

The intent of the categorizations is to restrict the use of medically important antimicrobials in animals to particular indications—particularly use in animals intended for food—while ensuring that sufficient therapeutic alternatives remain available to treat sick animals.

Relevant AVMA Policy: