# COMAR Title 15 — Maryland Department of Agriculture

## Subtitle 01 — Office of the Secretary

### Chapter 15 — Use of Antimicrobial Drugs

#### Regulation .03 When Permitted.

*COMAR 15.01.15.03*

A. Except as provided in this regulation, a person may administer a medically important antimicrobial drug to cattle, swine, or poultry if, in the professional judgment of a licensed veterinarian, the medically important antimicrobial drug is necessary:

  (1) To treat a disease or infection;

  (2) To control the spread of a disease or infection; or

  (3) For a surgery or medical procedure.

B. A person may administer a medically important antimicrobial drug to cattle, swine, or poultry if, in the professional judgment of a licensed veterinarian, the medically important antimicrobial drug is necessary for prophylaxis to address an elevated risk of contraction of a particular disease or infection.

C. Unless administration of a medically important antimicrobial drug is consistent with §A of this regulation, a person may not administer a medically important antimicrobial drug in a regular pattern to cattle, swine, or poultry.

D. A person may not administer a medically important antimicrobial drug to cattle, swine, or poultry solely for the purpose of:

  (1) Promoting weight gain; or

  (2) Improving feed efficiency.

E. Dry Cow Treatment.

  (1) General Rule Requiring Assessment. The administration of a medically important antimicrobial drug to a cow entering a dry cycle is prohibited except when the cow is diagnosed with a bacterial intramammary infection (mastitis).

  (2) Methods of Assessing Mastitis in an Individual Cow.

    (a) Tests. A person may assess the presence of mastitis in an individual cow through one or more of the following tests:

      (i) A positive bacterial culture test;

      (ii) A positive California Mastitis Test;

      (iii) A somatic cell count for an individual cow greater than 200,000 cells per milliliter in the most recent lactation; and

      (iv) Any other assessment method approved by the Secretary generally recognized by the American Association of Bovine Practitioners.

    (b) Signs of Mastitis. A person may assess the presence of mastitis in an individual cow using one or more of the following indicators:

      (i) Visibly abnormal milk including the presence of clots, blood, or discoloration; or

      (ii) Heat, pain, tenderness, or swelling of a gland.

    (c) A licensed veterinarian may assess the presence of mastitis in an individual cow through the observation of clinical signs of mastitis.