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Drug Tissue Residues


What is a Drug Residue?

Residue is defined by CVM (Center for Veterinary Medicine) as any compound or metabolite of a compound that is present in edible tissues from food animals because of the use of a compound in or on animals.

Drug Residue Information Form

Why is preventing drug residue important?

The goal is to provide safe consumer products and ensure consumer confidence in our food products.  By reducing drug residues in the consumer’s product we are also reducing the chance for any possible acute allergic or toxicity reaction by the consumer.  Preventing drug residues lends itself to also promote antimicrobial stewardship.  Through judicious use of drugs we are also helping decrease antimicrobial resistance which is both an animal and human health concern.


Who is involved in preventing drug residues?

Everyone!  Everyone can do their part in preventing drug residues. Beginning with farm workers properly giving and documenting medications given; the producer making sure the farm workers are properly trained and participating in ‘best practices’ to help reduce the risk of drug residues; the veterinarian prescribing appropriate drugs and knowing withdrawal times; FDA having clear rules and regulations; FARAD and various institutions to provide the scientific data needed to make guidelines and regulations on medications and practices used in the food animal industry; and the consumers for being invested in having access to a safe food product.


Who is involved in monitoring for drug residues?

Three agencies do most of the work to protect the public from residue and microbial hazards: the U.S. Department of Agriculture (USDA), including the Food Safety and Inspection Service (FSIS) and the Agricultural Marketing Service (AMS); the Food and Drug Administration (FDA); and the U.S. Environmental Protection Agency (EPA).  State Agencies also play a role.  State Department of Agriculture use federal regulations to establish more state-specific regulations and they will work collaboratively with the FDA and USDA to help provide surveillance and compliance.

Resource: reference

National Research Council (US) Committee on Drug Use in Food Animals. The Use of Drugs in Food Animals: Benefits and Risks.      https://www.ncbi.nlm.nih.gov/books/NBK232575/

The FARM Antibiotic Stewardship module



Drug Residue Educational Videos

ODA's animal health experts have created a number of educational videos about drug residue. Click here to watch.


Prevention of Drug Residues


10 Steps to Help Prevent Drug Residues

  1. Establish a valid Veterinarian-Client-Patient Relationship (VCPR) to ensure proper diagnosis and treatment of disease.
  2. Keep records of antibiotic use and identify all treated animals, including treatment protocols.
  3. Implement a preventive Herd Health Plan to reduce the incidence of disease.
  4. Maintain milk quality and implement an effective mastitis management program to reduce the use of antibiotics, including protocol development and review.
  5. Implement employee training and awareness of proper animal drug use
  6. Use drugs approved for specific disease indications according to labeled recommendations and withdrawal periods.  If extra label drug use is indicated by a veterinarian’s prescription, that veterinarian must establish and document appropriate withdrawal periods.
  7. Do not use drugs that are specifically prohibited for use in milking, dry or growing animals.
  8. Segregate and milk treated animals after or in a separate facility from all non-treated animals to ensure that milk is not accidently commingled.  Visibly mark these animals with a specific protocol.
  9. Use drug residue screening tests specifically for the drug utilized before marketing milk and or meat from treated animals.
  10. If in doubt about residue status, do not market milk and/ or cull treated animals CCHECK before you ship!<


Antimicrobial Stewardship


What is Antimicrobial Stewardship?

Antimicrobial stewardship is “the optimal selection, dosage, and duration of antimicrobial treatment that results in the best clinical outcome for the treatment or prevention of infection with minimal toxicity to the patient and minimal impact on subsequent resistance”.

Why is Antimicrobial Stewardship important?

Antimicrobial stewardship spans across human health, companion animals and livestock.  “Misuse and overuse of antimicrobials is one of the world’s most pressing public health concerns.  Infection organisms adapt to antimicrobials designed to kill them, making the drugs less effective.”  Less effective drugs will affect everyone in the future.

How can we slow the emergence of antimicrobial resistance?

To help slow down the emergence of antimicrobial resistance antimicrobial drugs should only be used when necessary to treat, prevent or control disease.  When these drugs are used, they should be given in an appropriate manner and under the supervision of a veterinarian.

What is the FDA doing to promote antimicrobial stewardship?

The FDA (Food and Drug Administration) has developed 3 key initiatives to promote antimicrobial stewardship:

  • Align antimicrobial drug products with the principles of antimicrobial stewardship in veterinary settings
    • FDA is enhancing processes of new product development and keeping industries up to date on antimicrobial drugs
  • Support efforts to foster stewardship of antimicrobials in veterinary settings
    • FDA is making efforts to increase education regarding antimicrobial use in animals
  • Assess the impact of strategies intended to curb the emergence of antimicrobial resistance associated with the use of antimicrobial drugs in veterinary settings
    • FDA is collecting data on the use of drugs in animals as well as antimicrobial resistance patters.  They are then using this data to help influence practices or make policies.


Common Causes of Antibiotic Residues in
Milk and Meat


These are not the only causes of antibiotic residues as every farm situation and practices are different.

  • Not working under a valid Veterinarian-Client-Patient Relationship
  • Not following veterinarian’s recommendation when using any drug
  • Not following the manufacturer or veterinarian prescribed label directions for correct treatment for the appropriate withdrawal time
  • Poor identification of all cattle including bull calves
  • Accidently milking a treated cow into the bulk tank or not diverting from the bulk tank
  • Long-term residue following treatment as a calf
  • Use of medicated milk replacers in calves that may be sold for human consumption
  • The use of prohibited drugs or aminoglycosides in cattle (the USDA and FDA are still detecting gentamicin residues in cattle)
  • The use of compounded medications in cattle (using multiple medications together can affect how they are metabolized and thus affect withdrawal time)
  • The practice of spraying hairy heel warts with antibiotic sprays in the parlor during milking can cause contamination
  • The use of sulfonamide products extra-label in lactating dairy cows


Source Reference: National Dairy Farm Program’s FARM Milk & Dairy Beef Drug Residue Prevention Reference Manual. https://nationaldairyfarm.com/wp-content/uploads/2019/06/DRM2019-Web.pdf


Most Common Drugs Found in Violations


Ceftiofur (Also known as Ceftiflex, Excede, Excenel, Naxcel and Spectramast)

  • Each product is different and has different withholding times and routes of administration, but all products have a pre-slaughter withdrawal time.

Enrofloxacin (Also known as Baytril 100)

  • Extra-label use in food animals is prohibited.  It is only labeled for non-lactating dairy animals 20 months or younger and beef animals for pneumonia.

Florfenicol (Also known as Nuflor, or Resflor Gold which contains Flunixin also)

  • Sustained release has a longer withdrawal period.  It is not approved for dairy cattle over 20 months of age.

Flunixin (Also known as Banamine, Flu-Nix, Flunixin, meglumine, and Prevail)

  • Only approved for intravenous administration; other routes of administration (IM or SQ) results in extended withdrawal times.


  • This drug has extended withdrawal times; FARAD recommends at least 2 years.  Use of this drug is STRONGLY discouraged.


  • This drug may be found in some medicated milk replacers- do not feed to calves that are being sent to slaughter.


  • Issues can arise when this drug is given longer than labeled, a different route than labeled, or a different frequency or amount than labeled without using an extended withdrawal period.


  • Use of any sulfonamide product not labeled for lactating dairy cows is illegal.  Using a sustained release product will change the withdrawal time as will using a higher dose or frequency.

Tetracycline (Oxy-tet, LA 200, LA 400)

  • Using this drug as an intrauterine infusion is considered extra-label.  Issues also arise from large volume injections at a single site (SQ) vs. IV administration.                                     

Source Reference: National Dairy Farm Program’s FARM Milk & Dairy Beef Drug Residue Prevention Reference Manual. https://nationaldairyfarm.com/wp-content/uploads/2019/06/DRM2019-Web.pdf


Preventing Drug Residues- Equipment Use and Drug Storage


Proper drug administration and handling can help prevent drug residues.  Here are some helpful hints for best practices:

  • Always use the drug as directed!
    • Make sure to read the drug label; consult your veterinarian with any questions
  • Single-use needles help prevent the spread of disease and cross contamination
    • At a minimum, it is recommended to change needles every 10 head
  • If reusable equipment is used, make sure it is properly disinfected.  Some equipment can be heat sterilized by boiling.  Also make sure to completely rinse any disinfectants- such as alcohol off.  If not properly rinsed they can neutralize vaccines or react with some medications.
  • Needles that break off and are left in the animal can migrate and cause serious issues.  These animals should NOT be sold or sent to a packer.  Contact your veterinarian immediately!
  • Store and dispose of needles properly
    • Make sure container is rigid and has a secure lid.
  • Train employees how to read label directions and properly give medications
  • Use clean sites for injections to help reduce risk for disease and site lesions
  • Dairy specific recommendations
    • Discard milk from all four quarters even if only one is treated
    • Mark treated animals in a highly visible way and train all employees to recognized treated animals and act accordingly
    • Milk treated cows last or in a separate area
    • Make sure not to send any calves fed antibiotic waste milk to slaughter

Drug Storage

It is necessary to keep records of all medications and treatments.  It is highly recommended to keep a drug inventory list.  Read the package insert when medications are purchased.  Various medications and products can have differing requirements on proper storage- follow the manufacturer’s storage instructions for each product.  Many products do require refrigeration. Store in a clean area and limit access to any drugs to those persons that are trained.  Store animal health products away from feed ingredients or mixing areas (unless it is specifically to be added to the feed).

Storage of partially used medication or vaccines is not recommended.

Properly dispose of drugs

For more information and resources regarding proper disposal of drugs visit:



Source Reference: National Dairy Farm Program’s FARM Milk & Dairy Beef Drug Residue Prevention Reference Manual. https://nationaldairyfarm.com/wp-content/uploads/2019/06/DRM2019-Web.pdf

Types of Drugs and Administration



Can be sold without a veterinary prescription- this is any sort of medication that can be purchased off the shelves in stores



Prescribed by a veterinarian, bought at a pharmacy.  The pharmacy may be via the veterinarian or a distributer.  Can only be sold to the producer by a veterinarian (or pharmacist)

Medicated Feed

(Veterinary Feed Directive)


A drug intended for use in or on feed, which is limited by an approved prescription application to use under the professional supervision of a licensed veterinarian












There are three different classes of drugs- over the counter (OTC), prescription (Rx), and medicated feed (VFD).  The type of class determines how a drug can be acquired as well as how they can be used.  Any type of drug can have the potential for causing a drug residue.

Types of injections:

  • IM Intramuscular (Administered in the muscle)
  • IMM Intermammary (Administered in the udder and does not use needle)
  • IV Intravenous (Administered in the vein)
  • SQ Subcutaneous (Administered under the skin)

By giving injections (especially IM injections) in the neck damage can be prevented to more important cuts of beef.  Some medications can be given at the base of the ear.  This is beneficial as the ears are removed and do not enter the food chain.  An example of how to give an injection at the base of ear (BOE) can be found at: https://www.zoetisus.com/products/beef/ excede/dosing-administration.aspx


Extra-Label Drug Use


What does Extra-Label Use mean?

Using a prescription or OTC drug in any way not specifically listed on the label is considered “extra-label drug use” and is illegal unless it is specifically prescribed by a veterinarian working in the context of a VCPR (and withdrawal times are given).  Most extra-label drug use will require an elongated withdrawal time.  All prescription drugs will have the statement “Federal law restricts this drug to use by or on the order of a licensed veterinarian”.

What are examples of ELDU?

Examples of extra-label use can include: changing the amount of a medication given or giving the medication longer than prescribed, changing the route of administration or amount given per injection site, or giving the medication for a disease or production class it is not labeled for.

Drugs not approved for ELDU:

The following drugs (or families of drugs) are prohibited for Extra-label animal drug uses in food-producing animals per 21 CFR Sec 530.41

  • Chloramphenicol
  • Clenbuterol
  • Diesthylstilbestrol (DES)
  • Ipronidazole
  • Other Nitroimidazoles
  • Furazolidone
  • Nitrofurazone
  • Fluoroquinolones
  • Glycopeptides

The following drugs have restricted extra-label use in food-producing animals:

  • Gentian Violet (prohibited in food or feed)
  • Cephalosporins (excluding cephapirin) use in cattle, swine, chickens or turkeys
    • Using Cephalosporin drugs at unapproved dose levels, frequencies, duration or routes of administration is prohibited
    • Using Cephalosporin drugs in cattle, swine, chickens or turkeys that are not approved for use in that species (ex. Cephalosporin drugs intended for humans or companion animals)
    • Using cephalosporin drugs for disease prevention
  • Phenylbutazone (prohibited in female dairy cattle 20 months or older)
  • Sulfonamide drugs in lactating dairy cattle (except approved use of sulfadimethoxine, sulfabromomethazine and sulfaethoxypyridazine)
  • Indexed drugs (see Farad.org for list)


Source Reference: National Dairy Farm Program’s FARM Milk & Dairy Beef Drug Residue Prevention Reference Manual. https://nationaldairyfarm.com/wp-content/uploads/2019/06/DRM2019-Web.pdf


Preventing Drug Residues-Record Keeping


Why keep drug records?

There are numerous reasons to keep records regarding the medication use on your farm.  For starters keeping records helps to prevent an accidental residue violation.  Records can also help improve your veterinarian’s effectiveness and ensure an effective herd health plan. Records also reduce liability as drug records are required by law.  In many ways keeping good records can help save money.


What should be included in drug records?

  • Treatment date
  • Name of drug
  • Animal identification
  • Dosage
  • Route of administration
  • Expected duration
  • Withdrawal time for milk and meat
  • Individual who administered the drug
  • Actual duration of therapy

Veterinarians must keep their records (written or electronic) for a minimum of two years.  While it is not mandatory that producers keep records on animals treated with drugs for two years it is STRONGLY recommended they do.  Some drug records are required by law.  It is a sign of good management for producers to keep complete, accurate, and clear records- especially when dealing with drug use. Records can include but are not limited to: Drug inventory, drugs purchased, treatments, veterinary relevant information, and how drugs were disposed.

Examples of record keeping templates can be found at:


Under FARM Resources > Antibiotics Stewardship Resources


Source Reference: National Dairy Farm Program’s FARM Milk & Dairy Beef Drug Residue Prevention Reference Manual. https://nationaldairyfarm.com/wp-content/uploads/2019/06/DRM2019-Web.pdf


Veterinary Feed Directive-VFD


What is the Veterinary Feed Directive or VFD?

VFD mandates the rules and responsibilities of licensed veterinarians in prescribing and administering medically important antibiotics in feed or water.  The veterinarian must have a valid Veterinarian-Client- Patient- Relationship to prescribe a VFD drug.

What is a medicated feed?

Medicated feed is any nutrient source (other than drinking water) that contains a drug (a drug is a substance other than food that is intended to affect the structure or function of the body).  It could be a complete feed, a free-choice supplement, top dress, milk replacer, or premix.  Medicated feeds can allow for an easy, safe, and stress-free method to administer medication to animals.  Depending on the category and type medicated feed can be over-the-counter from a licensed medicated feed mill or under a VFD.

What are some of the medically important antibiotics used?

  1. Aminoglycosides
  2. Lincosamides
  3. Macrolides
  4. Penicillins
  5. Streptogramins
  6. Sulfonamides
  7. Tetracyclines

Note: Ionophores (such as monensin) are not affected by the guidance since they have no human medical relevance

There are no VFD drugs approved for use in lactating dairy cattle.

There are no legal extra-label uses of VFD drugs.


Who is in charge of VFD?

The FDA oversees the regulating of medicated feed, licensing medicated feed mills, and veterinary feed directives.

Regulations can be found under: 21 CFR 514 and 21 CFR Part 55  


Source References: National Dairy Farm Program’s FARM Milk & Dairy Beef Drug Residue Prevention Reference Manual. https://nationaldairyfarm.com/wp-content/uploads/2019/06/DRM2019-Web.pdf



Prevention of Drug Residues
Withdrawal Time and FARAD


What is a withdrawal time?

A withdrawal time is the period of time from when a drug is administered to when the drug concentration falls below the tolerance.  Withdrawal times exist for both meat and milk. Every approved livestock drug has a withdrawal time, but this only applies when the drug is used according to the label.  If used differently than stated on the manufacturer’s label the withdrawal time is likely different.


Why is it important to follow?

Not following withdrawal times significantly increases the risk of unwanted drug residues in consumer food products.  This can lead to lack of confidence from consumers that their food products are safe and avoid allergic and toxic reactions.  Inappropriate use of antimicrobials may lead to antimicrobial resistance.


What is FARAD?

FARAD stands for Food Animal Residue Avoidance Databank.  It is a component of the Food Animal Residue Avoidance & Depletion Program.  It is a national program that serves as the primary source for scientifically-based recommendations regarding safe withdrawal intervals of drugs and chemicals in food-producing animals.  FARAD is a great resource for protection of our nation’s food supply.


Services offered by FARAD:


Withdrawal date calculator- helps to determine the safe withdrawal time


WDI look up tool- withdrawal interval recommendations for some extra-label uses of limited drugs


Extra-Label-Drug-Use advice- information and a resource for licensed veterinarians regarding ELDU


Search Vetgram- online database of uses, restrictions and required withdrawal times for drugs approved in food animal species


Species Specific pages- information and resources for specific species


Citations database- information regarding chemicals and their time vs. concentration data in live animals


Source Reference- FARAD- http://www.farad.org/