§ 520.48 Altrenogest.

Specifications.(a) Each milliliter (mL) of solution contains 2.2 milligrams (mg) altrenogest.

Sponsors.(b) See sponsors in § 510.600(c) of this chapter:

(1) Nos. 000061 and 051072 for use as in paragraph (d) of this section.

(2) No. 061133 for use as in paragraph (d)(1) of this section.

(3) No. 053701 for use as in paragraph (d)(2) of this section.

Tolerances.(c) See § 556.36 of this chapter.

HorsesAmount.(d) Conditions of use—(1) —(i) 1.0 mL per 110 pounds body weight (0.044 mg/kg) daily for 15 consecutive days.

Indications for use.(ii) For suppression of estrus in mares.

Limitations.(iii) Do not use in horses intended for human consumption. Federal law restricts this drug to use by or on the order of a licensed veterinarian.

SwineAmount.(2) —(i) Administer 6.8 mL (15 mg altrenogest) per gilt once daily for 14 consecutive days by top-dressing on a portion of each gilt's daily feed.

Indications for use.(ii) For synchronization of estrus in sexually mature gilts that have had at least one estrous cycle.

Limitations.(iii) Do not use in gilts having a previous or current history of uterine inflammation (i.e., acute, subacute or chronic endometritis). Gilts must not be slaughtered for human consumption for 21 days after the last treatment.

[66 FR 47960, Sept. 17, 2001, as amended at 68 FR 62006, Oct. 31, 2003; 72 FR 9455, Feb. 21, 2008; 74 FR 61516, Nov. 25, 2009; 77 FR 32012, May 31, 2012; 80 FR 34278, June 16, 2015; 82 FR 21690, May 10, 2017; 83 FR 13635, Mar. 30, 2018; 84 FR 8972, Mar. 13, 2019; 88 FR 27698, May 3, 2023; 91 FR 20340, Apr. 16, 2026]