(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.

(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.