# Agriculture (GAG)

## Title 3. Regulation of Livestock and Poultry

### Subtitle 10. Use of Antimicrobial Drugs

#### Section 3-1003

(a) A medically important antimicrobial drug may not be administered in feed or water to cattle, swine, or poultry unless ordered by a licensed veterinarian through:

  (1) A medically important antimicrobial drug prescription; or

  (2) A veterinary feed directive.

(b)

  (1) On or after January 1, 2018, and subject to subsection (c) of this section, a medically important antimicrobial drug may be administered to cattle, swine, or poultry if, in the professional judgment of a licensed veterinarian, the medically important antimicrobial drug is necessary:

    (i) To treat a disease or infection;

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

    (iii) For a surgery or medical procedure.

  (2)

    (i) On or after January 1, 2018, a medically important antimicrobial drug may be administered 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.

    (ii) Notwithstanding subsection (e) of this section, administration of a medically important antimicrobial drug for the purpose of prophylaxis may not exceed 21 days unless federal label directions require a longer period of use.

(c) Unless administration of a medically important antimicrobial drug is consistent with subsection (b)(1) of this section, a medically important antimicrobial drug may not be administered in a regular pattern to cattle, swine, or poultry.

(d) A medically important antimicrobial drug may not be administered to cattle, swine, or poultry solely for the purpose of:

  (1) Promoting weight gain; or

  (2) Improving feed efficiency.

(e)

  (1) Except as provided in paragraphs (2) and (3) of this subsection, a medically important antimicrobial drug may not be administered to cattle, swine, or poultry for a period longer than 21 days.

  (2) A medically important antimicrobial drug may be administered to cattle, swine, or poultry for a period longer than 21 days if the federal label directions for the drug require a longer period of use.

  (3)

    (i) A licensed veterinarian may extend administration of a medically important antimicrobial drug for not more than 21 days if, after conducting an on-site visit, the veterinarian determines that the extension is necessary to treat or control the spread of disease or infection.

    (ii) A licensed veterinarian may grant additional extensions of not more than 21 days, provided that the veterinarian conducts an on-site visit before each extension.

(f) On or before January 1, 2021, the Department shall adopt regulations prohibiting the routine administration of a medically important antimicrobial drug to dairy cattle entering a dry cycle except when necessary based on an assessment of the presence of an intramammary infection.

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Md. Code Ann., Agric. (as displayed at mgaleg.maryland.gov, October 16, 2026)