The Need to Read

Table of Contents

Drug Label Directions Enhance Health of Livestock and Bottom Line

The information contained on a drug label, or product monologue as the pharmaceutical industry calls it, explains how to use the drug safely. When you follow the directions, you get the optimum benefit from the drug.

A package insert-the leaflet not attached to the drug container may accompany a medicine container in the same box. These product inserts often contain critical and more detailed information than what is printed on the container's label.

Read the inserts carefully before using the product. Ignoring them may result in missing vital information. That could put animals to be treated and the person handling the product at risk. Moreover, you could jeopardize food safety and quality.

Many drug manufacturers and distributors ensure these inserts accompany the drugs when you buy them. Other companies send a bundle of inserts along with the product, relying on the retailer to put the two together .

If you don't get an insert with a drug purchase, ask your retailer if the information accompanying your purchase is complete. Otherwise you may not get the complete bang for your buck.

The federal Food and Drugs Act tells manufacturers what information must appear on a label itself. This is to ensure safe storage and use. Here's what you typically read on a label and why it's so important:


The front and side panels of a drug container describe the product and its use. Next to the name of the product will be some indication of its classification. The Pr symbol identifies the product as a prescription drug.

No Pr suggests that no prescription is required for its purchase. This does not necessarily mean it's available for over-the-counter sale (see the section on the Livestock Medicines Act). There is no designator for over- the-counter drugs.

Drug Identification Number

All drugs, before they can be sold legally in Canada, must be assigned a Drug Identification Number (DIN) . Health Canada requires manufacturers to provide data ensuring product safety, effectiveness in satisfying label claims, potency and purity. Once the manufacturer meets these criteria, Health Canada issues a registration number for the drug.

These measures provide confidence that medicines have been adequately tested and are safe for the use intended, when administered according to label directions. The DIN should appear somewhere on the front panel, DIN: 123456, for example. Avoid purchasing or using products that lack a DIN.

Active Ingredients

The product's brand name is registered with the Veterinary Drugs Directorate (VDD), a division of Health Canada. The brand name is followed by the registered trademark symbol (TM or ®) of the manufacturer. Below the brand name, you generally see the active ingredient the medicine contains and its concentration or strength. This component produces the desired effect of the medicine as claimed on the label, such as ". ..indicated for treatment of livestock bacterial infection associated with pneumonia." The front panel provides a detailed description of the product. This description indicates whether the medicine is an antibacterial, a vaccine or a wound dressing.


The drug's formulation directly follows the active ingredient. This indicates whether it's an injectable product, a powder or a topical preparation. It provides our first clue for how to administer the medicine, but the dosage and administration section makes it clearer .


The volume of liquid or weight for non-liquid medicines appears in millilitres (mL) or grams and is found on the front panel as well. This information is essential in calculating proper dosages. For any drug product to be effective, and to avoid problems with residues or over- or under- dosing, you have to calculate dosages correctly. Manufacturers suggest dosages on the label that are safe and effective for the animal. Using too little will result in poor results; too much could lead to residues in animal products. Either one decreases the product's cost effectiveness. When calculating dosage, consider these factors:

  • animal weight;
  • size of dose;
  • how and where you'll administer the drug;
  • how often you'll administer the dose;
  • how long the treatment will last.


You need to know if the medicine is for veterinary or human use. All medicines intended for use in animals will have Veterinary Use Only stated on the front label. Medicines designed to make animals well again can have detrimental effects on human or animal health when used improperly. The warning addresses any cautions you should know about, such as the withdrawal time- the recommended time between the last drug treatment and the shipping for sale of milk or meat in the case of dairy cows. It's required for residues to deplete to safe levels. Any restrictions are also included in the warning statement, such as "not for use in lactating dairy cows. "

Other Information

The manufacturer's name and address gives you a point of contact for further information about the product. The side panel of the label actually instructs us how to use this drug product, as well as how to store it to ensure it will continue to be effective in the future. There may be a caution statement associated with storage and handling. Typical precautions may include "store below 25 degrees C" or "Keep out of reach of children. "

Lot Numbers

Lot numbers are assigned to products by manufacturers and are a useful reference if adverse reactions occur. In these cases, this number may be needed for product investigations and recalls.

Expiry Date

An expiry date, assigned by the manufacturer, indicates the date past which the drug should not be used. The Livestock Medicines Act prohibits retail outlets from offering for sale drugs that have expired.

Extra-Label Use

Health Canada's approval process clears a drug for use in specific species. Any use of a drug in a species not indicated on the label constitutes "extra-label" use and may result in unpredictable results. Extra-label use of medicines generally is discouraged. Proper dosages and subsequent withdrawal times are unknown and may result in residues.

Veterinarians can legally prescribe drugs in an extra-label manner, but must leave a treatment prescription with you at the time of the visit. This information must identify the product, the species and class of animal for which the product is to be used, directions for use and withdrawal times.

As well, the label must indicate the name of the veterinary clinic and the veterinarian prescribing the product. Warnings, cautions or precaution statements, and storage information must also be included.

While medicines represent a significant financial investment, they're an essential tool in modern animal husbandry. It's paramount to use them wisely to ensure effectiveness and avoid the potentially high costs associated with product residues.

There are four critical times to read a drug label:

  • before you buy a medicine;
  • before you use a medicine;
  • before you store a medicine;
  • before you dispose of a medicine.

You need to take time to read the label of livestock medicine as well as any inserts.

This information may influence your decision on whether to buy the product or how to use it. Either way, you'll be a more informed consumer and more confident that you have administered the drug in a safe and responsible manner .

References: Livestock Medicines Manual. Second Edition; OMAFRA. ISBN0-7778-3541-X. P.31

This document is a revised version of an article that appeared in the March 2002 Ruminations column in the Ontario Milk Producer.

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