Skip to main content

Safe-Guard Medicated Dewormer for Beef Cattle (20% Protein Block)

This page contains information on Safe-Guard Medicated Dewormer for Beef Cattle (20% Protein Block) for veterinary use.
The information provided typically includes the following:
  • Safe-Guard Medicated Dewormer for Beef Cattle (20% Protein Block) Indications
  • Warnings and cautions for Safe-Guard Medicated Dewormer for Beef Cattle (20% Protein Block)
  • Direction and dosage information for Safe-Guard Medicated Dewormer for Beef Cattle (20% Protein Block)

Safe-Guard Medicated Dewormer for Beef Cattle (20% Protein Block)

This treatment applies to the following species:
Company: Intervet/Merck Animal Health


Medicated Dewormer for Beef Cattle

20% Protein Block

Type C free-choice medicated feed

Withdrawal Periods and Residue Warnings: Cattle must not be slaughtered for human consumption within 16 days following last treatment with this drug product. Not for use in female dairy cattle 20 months of age or older, including dry dairy cows; use in these cattle may cause drug residues in milk and/or in calves born to these cows or heifers. Not for use in beef calves less than 2 months of age, dairy calves, and veal calves. A withdrawal period has not been established for this product in pre-ruminating calves.

Consult your veterinarian for assistance in the diagnosis, treatment and control of parasitism.

Safe-Guard Medicated Dewormer for Beef Cattle (20% Protein Block) Indications

For the treatment and control of: Lungworms: Adult Dictyocaulus viviparus; Stomach worms: Adult brown stomach worms (Ostertagia ostertagi), Adult and fourth stage larvae barberpole worms (Haemonchus contortus), fourth stage larvae barberpole worms (H. placei), and Adult and fourth stage larvae small stomach worms (Trichostrongylus axei); Intestinal worms (Adult and fourth stage larvae): hookworms (Bunostomum phlebotomum), thread-necked intestinal worms (Nematodirus helvetianus), small intestinal worms (Cooperia punctata & C. oncophora), bankrupt worms (Trichostrongylus colubriformis), and nodular worms (Oesophagostomum radiatum).


1.67 mg fenbendazole per kg body weight per day for three (3) days. Total dose for the three (3) day period of 5 mg fenbendazole per kg of body weight (2.27 mg fenbendazole per pound).

Do not underdose. Ensure each animal receives a complete dose based on a current body weight. Underdosing may result in ineffective treatment, and encourage the development of parasite resistance.



750 mg/lb


Crude Protein



Crude Fat



Crude Fiber



Calcium (Ca)



Calcium (Ca)



Phosphorus (P)



Salt (NaCl)



Salt (NaCl)



Magnesium (Mg)



Cobalt (Co)


3 ppm

Copper (Cu)


200 ppm

Fluorine (F)


100 ppm

Iodine (I)


20 ppm

Manganese (Mn)


500 ppm

Zinc (Zn)


800 ppm

Vitamin A


20,000 IU/lb

Vitamin D-3


5,000 IU/lb


Cottonseed Meal, Dehydrated Alfalfa Meal, Salt, Cane Molasses, Calcium Carbonate, Magnesium Limestone, Defluorinated Phosphate, Lignin Sulfonate, Calcium Bentonite, Rice Hulls, Zinc Oxide, Copper Sulfate, Manganous Oxide, Zinc Sulfate, Ferrous Sulfate, Manganese Sulfate, Vitamin A Supplement, Mineral Oil, Calcium Iodate, Magnesium Sulfate, Potassium Sulfate, Vitamin D-3 Supplement, Cobalt Sulfate.


Adequate forage must be available at all times to cattle receiving supplemental block feeding. Safe-Guard® (fenbendazole) 20% Protein Deworming Block (Medicated) is designed for deworming pastured cattle by feeding these medicated blocks for three (3) days only as the sole source of salt. It is essential to establish full cattle adaptation to supplemental block feeding prior to treating cattle with Safe-Guard® 20% Protein Deworming Block (Medicated). Cattle behavior and per capita consumption must be established by feeding nonmedicated 20% Protein Blocks prior to medicated block treatment. Adaptation to block feed intake for medicated treatment may take twelve (12) to nineteen (19) days of prior exposure to unmedicated feed blocks depending on consumption rates and environmental conditions. When cattle block consumption of 0.1 pound (1.6 ounces) per 100 pounds of body weight (or 1.0 pound for a 1000-pound cow) per day is attained for several days on the nonmedicated 20% Protein Block, the three (3) day medicated treatment with Safe-Guard® 20% Protein Deworming Blocks (Medicated) may begin. For effective treatment, the cattle must consume an average 0.1 pound of Safe-Guard® 20% Protein Deworming Blocks (Medicated) per 100 pounds of body weight each day for the three (3) days of treatment. This is equivalent to an average of one (1) pound per head per day to a 1000-pound cow for the three days of treatment in order to provide a total dose of 2.27 mg fenbendazole per pound of body weight. To commence deworming treatment, replace the nonmedicated blocks with Safe-Guard® 20% Protein deworming Blocks (Medicated). Place these medicated blocks at the same locations where cattle have demonstrated adequate per capita block intake (0.1 pound per 100 pounds of body weight per day).

DAILY TREATMENT (To be continued for three [3] days):

Cattle Body Weight

Average Block Intake

Number of Head
Per Block*











Following the three (3) day treatment any remaining Safe-Guard® 20% Protein Deworming Blocks (Medicated) should be removed from the pasture and cattle may be returned to their normal supplemental feeding program. Remaining blocks, or portions of blocks, can be utilized for retreatment purposes if used prior to the expiration date shown below. It is essential that good block feeding husbandry practices be followed at all times. Block feeding techniques include, but are not limited to, a variety of practices. Blocks should be first located in those areas where cattle are seen to browse or loaf. It may be desirable to relocate unconsumed blocks to locations where obvious block consumption is identified. Increased consumption may often be obtained by moving feeding stations into shaded or loafing areas, closer to water source, increasing the number of blocks available to the animals or combinations of these practices. Decreased consumption may often be obtained by the reverse of the above practices.


Not for use in humans. Keep out of reach of children. The Safety Data Sheet (SDS) contains more detailed occupational safety information. For customer service, adverse effects reporting, and/or a copy of the SDS, call 1-800-211-3573. For additional information about adverse drug experience reporting for animal drugs, contact FDA at 1-888-FDAVETS, or

OTHER WARNINGS: Parasite resistance may develop to any dewormer, and has been reported for most classes of dewormers. Treatment with a dewormer used in conjunction with parasite management practices appropriate to the geographic area and the animal(s) to be treated may slow the development of parasite resistance. Fecal examinations or other diagnostic tests and parasite management history should be used to determine if the product is appropriate for the herd, prior to the use of any dewormer. Following the use of any dewormer, effectiveness of treatment should be monitored (for example, with the use of a fecal egg count reduction test or another appropriate method). A decrease in a drug’s effectiveness over time as calculated by fecal egg count reduction tests may indicate the development of resistance to the dewormer administered. Your parasite management plan should be adjusted accordingly based on regular monitoring.

Approved by FDA under NADA # 139-189

Manufactured by Ridley USA Inc. for:

Intervet Inc. (d/b/a Merck Animal Health) Madison, NJ 09740

©2020 Intervet Inc., a subsidiary of Merck & Co. Inc.

Rev. 09/2020

Net Weight


25 LBS (11.34 kg)

396127 R11

319382 R13

CPN: 1047390.2

Intervet Inc.

Customer Service:   800-521-5767
Order Desk:   800-648-2118
Technical Service (Companion Animal):   800-224-5318
Technical Service (Livestock):   800-211-3573
Fax:   973-937-5557
THIS SERVICE AND DATA ARE PROVIDED "AS IS". DVMetrics assumes no liability, and each user assumes full risk, responsibility, and liability, related to its use of the DVMetrics service and data. See the Terms of Use for further details.

Copyright © 2023 Animalytix LLC. Updated: 2023-05-30