1. 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. (1) To treat a disease or infection;
   2. (2) To control the spread of a disease or infection; or
   3. (3) For a surgery or medical procedure.
2. 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.
3. 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.

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

   1. (1) Promoting weight gain; or
   2. (2) Improving feed efficiency.

5. E. Dry Cow Treatment.

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

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

         1. (i) A positive bacterial culture test;
         2. (ii) A positive California Mastitis Test;
         3. (iii) A somatic cell count for an individual cow greater than 200,000 cells per milliliter in the most recent lactation; and
         4. (iv) Any other assessment method approved by the Secretary generally recognized by the American Association of Bovine Practitioners.

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

         1. (i) Visibly abnormal milk including the presence of clots, blood, or discoloration; or
         2. (ii) Heat, pain, tenderness, or swelling of a gland.
      3. (c) A licensed veterinarian may assess the presence of mastitis in an individual cow through the observation of clinical signs of mastitis.

Authority: Agriculture Article, §§3-1001—3-1003, 3-1005, and 3-1006, Annotated Code of Maryland

Effective date: January 28, 2019 (46:2 Md. R. 53)

Regulation .02 amended as an emergency provision effective April 12, 2019 (46:9 Md. R. 444); amended permanently effective September 9, 2019 (46:18 Md. R. 775)

Regulation .02B amended effective January 14, 2021 (48:1 Md. R. 10)

Regulation .03E adopted effective January 14, 2021 (48:1 Md. R. 10)

Regulation .04 amended effective January 14, 2021 (48:1 Md. R. 10)