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Classes of Drugs

This section is intended to provide background information on many of the
types of drugs that may be encountered on dairy farms. Included are common
classes of drug compounds and a brief description and some common examples of
those compounds. Some of the drugs listed are not approved for use in dairy cattle.

NOTE: LISTING OF DRUGS OR PRODUCT TRADE NAMES DOES NOT IMPLY
AN ENDORSEMENT OF THEIR USE IN DAIRY CATTLE.

I. ANTIMICROBIAL DRUGS

Antibiotics and antibacterial products are drugs primarily intended for the
treatment of infections caused by bacterial organisms and other microbes.
These products are not effective for treating viral or fungal infections. They are
however sometimes used to treat those secondary bacterial infections occurring
simultaneously with viral and fungal infections.

Some of the more common bacterial infections in dairy cattle include mastitis
(mammary infection), metritis (uterine infection), pneumonia (respiratory
infection), some diarrheal infections, foot rot, and infrequently encephalitis.
These products are used to treat abscesses, wounds and to treat or prevent
infections after surgery.

Antimicrobials are divided into classes. The following list provides these classes
and examples of active ingredients in each class.

A. Sulfonamides

 Sulfathiazole  Sulfaethoxypyridazine
 Sulfamethazine  Sulfadimethoxine
 Sulfamerazine  Sulfachloropyridazine
 Sulfadiazine  Sulfanilamide
 Sulfabromomethazine

The sulfonamides, particularly sulfamethazine (SMZ), have received a great
deal of attention in recent years. Sulfamethazine has been used in veterinary
medicine in several animal species for more than 25 years. The sulfonamides
have been widely used in human medicine for more than 40 years.

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