21 CFR § 520.2220e - Sulfadimethoxine extended-release bolus.

---
identifier: "/us/cfr/t21/s520.2220e"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 520.2220e - Sulfadimethoxine extended-release bolus."
title_number: 21
title_name: "Food and Drugs"
section_number: "520.2220e"
section_name: "Sulfadimethoxine extended-release bolus."
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"
---


# 520.2220e Sulfadimethoxine extended-release bolus.

(a) *Specifications.* Each extended-release bolus contains 12.5 grams sulfadimethoxine.

(b) *Sponsor.* See No. 054771 in § 510.600(c) of this chapter.

(c) *Related tolerances.* See § 556.640 of this chapter.

(d) *Conditions of use in beef cattle and non-lactating dairy cattle*—(1) *Amount.* Administer one 12.5-gram-sustained-release bolus for the nearest 200 pounds of body weight, i.e., 62.5 milligrams per pound of body weight. Do not repeat treatment for 7 days.

(2) *Indications for use.* For the treatment of shipping fever complex and bacterial pneumonia associated with *Pasteurella* spp. sensitive to sulfadimethoxine; and calf diphtheria and foot rot associated with *Fusobacterium necrophorum* sensitive to sulfadimethoxine.

(3) *Limitations.* Do not use in female dairy cattle 20 months of age or older. Do not administer within 12 days of slaughter. Federal law restricts this drug to use by or on the order of a licensed veterinarian.

[79 FR 28830, May 20, 2014]