Section 2 | Reading Livestock Medicines Labels

Livestock Medicines
Page 09 /

Extra-Label Drug Use

What is Extra-Label Drug Use?

Use of a product in a way that is different from what is written on its label instructions is called extra-label drug use (ELDU).


ELDU is when the product is used in a manner other than what is specified on the label, such as:

  • In a different species
  • At a different dose (e.g. higher or lower)
  • For a longer period of time
  • By a different route of administration
  • At a different treatment frequency
  • In combination with other drugs
  • For a different class of animals (e.g. in lactating cows rather than non-lactating cows)
  • For a different disease condition


Examples of ELDU include:

  • Doubling the dose of Draxxin® for treating incoming steers in the feedlot
  • Using Anafen®
  •  in laying hens
  • Treating a dairy cow with metritis with penicillin for one month
  • Using tetracycline topically on footrot
  • Giving pigs with pneumonia twice-daily Trimidox®
  •  (instead of once daily)
  • Using the mastitis treatment tube Special Formula 17900 Forte® to treat eye injuries in horses

Why Use Drugs Extra-Label at All?

There is a need for ELDU, as there are no drugs labelled to treat some conditions in animals. For example, small ruminants (goats in particular) have very few drugs that are currently approved for use. However, there are drugs that are approved for other species that can work in sheep and goats, and must therefore be used in an extra-label manner.

Only veterinarians have the ability to use and prescribe drugs in an extra-label manner for animals. So animal owners MUST use medicines in accordance with label instructions, unless otherwise instructed by their veterinarian.

ELDU is only allowed under the supervision of a licensed veterinarian. The FIRST choice for drug use MUST be according to label directions!


In order to access prescription antimicrobials, you need to establish a relationship with a licensed veterinarian. For more information on establishing a valid veterinary-client-patient relationship (VCPR), see Animal Owner FAASTsheet #5.

ELDU is only allowed under the supervision of a licensed veterinarian

Accountability and Liability

ELDU may be dangerous to animals and could lead to residues in human food. Anyone who uses a product extra-label without veterinary supervision is doing so at their own risk. If something goes wrong, only that person using the drugs without supervision (not the manufacturer, not the regulatory authorities, not their veterinarian) is to blame.


Veterinarians should only resort to ELDU when:

  • No suitable drug is labelled for the required purpose
  • The health of the animals to be treated is immediately threatened
  • The risk of suffering or death will be great without immediate treatment

Withdrawal Times

It is very important to understand that the withdrawal time given on the label DOES NOT apply in ELDU. Veterinarians prescribing drugs extra-label are responsible for recommending proper withdrawal times and for giving warnings for human safety and cautions for animal safety.

BOTH the veterinarian and animal owner are responsible for ensuring that no illegal drug residues result from ELDU.


Guidelines for Veterinarians Choosing ELDU

The attending veterinarian must:

  • Make a careful medical diagnosis
  • Determine that there is no on-label options to treat the disease OR that the dosage recommended on the label is not effective
  • Be confident that the drug will not harm the animals
  • Identify (with the producer) all treated animals carefully (including maintaining treatment records)
  • Assign a different withdrawal time, in consultation with CgFARAD*
  • Ensure there are no illegal residues in animal products after treatment


*CgFARAD = Canadian Global Food Animal Residue Avoidance Database

Globally funded group that provides advice to veterinarians regarding withdrawal times for drugs used in an extra-label manner in food-producing animals.

Forbidden Drugs – These are NOT to be Used Extra-Label

Federal regulations forbid the use of some drugs in food-producing animals. If you are found to be using these restricted drugs in food-producing animals, you could face large fines or prison.

Drugs not permitted for food-producing animals in Canada include:
Chloramphenicol (an antimicrobial)
Clenbuterol (asthma treatment drug)
Diethylstilbestrol (a synthetic estrogen)
𝛼5-nitrofuran compounds (an antimicrobial)
Estrogenic products (in poultry)
Ethylenediamine dihydroiodide
Drugs not permitted for food-producing animals in the United States include:
Chloramphenicol (an antimicrobial)
Clenbuterol (asthma treatment drug)
Diethylstilbestrol (a synthetic estrogen)
𝛼5-nitrofuran compounds (an antimicrobial)
Dimetridazole, metronidazole, ipronidazole, nitroimidazole (antiparasitics)
Sulfonamide drugs in dairy cattle older than 20 months (except approved use of sulfadimethoxine)
Dipyrone (anti-inflammatory)
Glycopeptides (antimicrobial)
Extra-label use of medically important antimicrobial medications