21 CFR § 520.1441 - Milbemycin.

---
identifier: "/us/cfr/t21/s520.1441"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 520.1441 - Milbemycin."
title_number: 21
title_name: "Food and Drugs"
section_number: "520.1441"
section_name: "Milbemycin."
chapter_name: "FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "E"
subchapter_name: "ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS"
part_number: "520"
part_name: "ORAL DOSAGE FORM NEW ANIMAL DRUGS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "21 U.S.C. 360b."
regulatory_source: "40 FR 13838, Mar. 27, 1975, unless otherwise noted."
cfr_part: "520"
---


# 520.1441 Milbemycin.

(a) *Specifications.* Each flavored tablet contains 2.3, 5.75, 11.5, or 23.0 milligrams (mg) of milbemycin oxime.

(b) *Sponsors.* See Nos. 013744 and 058198 in § 510.600(c) of this chapter.

(c) *Conditions of use*—(1) *Dogs*—(i) *Amount.* For hookworm, roundworm, and whipworm, administer 0.23 mg per pound (mg/lb) of body weight (0.5 mg per kilogram (mg/kg)). For heartworm, administer 0.05 mg/lb of body weight (0.1 mg/kg). Administer once a month.

(ii) *Indications for use.* For prevention of heartworm disease caused by *Dirofilaria immitis,* control of hookworm infections caused by *Ancylostoma caninum,* and removal and control of adult roundworm infections caused by *Toxocara canis* and *Toxascaris leonina* and whipworm infections caused by *Trichuris vulpis* in dogs and puppies 4 weeks of age or greater and 2 pounds body weight or greater.

(iii) *Limitations.* Federal law restricts this drug to use by or on the order of a licensed veterinarian.

(2) *Cats*—(i) *Amount.* Administer 0.91 mg/lb of body weight (2.0 mg/kg) once a month.

(ii) *Indications for use.* For prevention of heartworm disease caused by *Dirofilaria immitis* and the removal of adult *Toxocara cati* (roundworm) and *Ancylostoma tubaeforme* (hookworm) infections in cats 6 weeks of age or greater and 1.5 pounds body weight or greater.

(iii) *Limitations.* Federal law restricts this drug to use by or on the order of a licensed veterinarian.

[84 FR 12494, Apr. 2, 2019]