Synanthic Bovine Dewormer: Product Information

SYNANTHIC BOVINE DEWORMER- oxfendazole suspension
Boehringer Ingelheim Animal Health USA Inc.

Each mL contains 225 mg of oxfendazole.

The entire contents of the 500 mL bottle treats 110 cattle weighing approximately 500 lbs each.

The entire contents of the 1000 mL bottle treats 220 cattle weighing approximately 500 lbs each.

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


SYNANTHIC Bovine Dewormer Suspension, 22.5%, is a broad-spectrum anthelmintic effective for the removal and control of the following parasites in cattle: lungworms, roundworms (including inhibited forms of Ostertagia ostertagi) and tapeworms, as indicated below:


Dictyocaulus viviparus (Adult, L4 )

Stomach Worms:

Barberpole Worms

Haemonchus contortus (Adult)

Haemonchus placei (Adult)

Small Stomach Worms

Trichostrongylus axei (Adult)

Brown Stomach Worms

Ostertagia ostertagi (Adult, L4 , inhibited L4 )

Intestinal Worms:

Nodular Worms

Oesophagostomum radiatum (Adult)


Bunostomum phlebotomum (Adult)

Small Intestinal Worms

Cooperia punctata (Adult, L4 )

Cooperia oncophora (Adult, L4 )

Cooperia surnabada (Adult, L4 )


Moniezia benedeni (Adult)

Administration and Dosage:

SYNANTHIC Bovine Dewormer Suspension, 22.5%, is supplied in 500 mL and one liter packages containing 225 mg of oxfendazole per mL. The recommended dose for cattle is 2.05 mg/lb (4.5 mg/kg) of body weight. SYNANTHIC Bovine Dewormer Suspension, 22.5%, should be administered orally by accurate dose syringe at the rate of 1 mL per 110 lb (50 kg) of body weight. This product should be shaken well immediately prior to use. 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.

Remove Cap and Protective Seal and Replace with Draw Off Cap Prior to Use. Do Not Squeeze Sides of Bottle. Replace the Draw Off Cap with the Initial Cap after Use.


Determine the proper dose according to estimated body weight. Administer orally. The recommended dose of 2.05 mg/lb (4.5 mg/kg) is achieved when 1 mL of the suspension is given for each 110 lb (50 kg) of body weight.


Cattle Weight


110 lb (50 kg)

1.0 mL

220 lb (100 kg)

2.0 mL

330 lb (150 kg)

3.0 mL

440 lb (200 kg)

4.0 mL

550 lb (250 kg)

5.0 mL

660 lb (300 kg)

6.0 mL

770 lb (350 kg)

7.0 mL

880 lb (400 kg)

8.0 mL

990 lb (450 kg)

9.0 mL

1100 lb (500 kg)

10.0 mL

Treatment may be repeated in 4–6 weeks.

Residue Warnings:

Cattle must not be slaughtered until 7 days after treatment. Because a withdrawal time in milk has not been established, do not use in female dairy cattle of breeding age.

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/flock, 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.


Use only as directed. Keep out of reach of children. Not for human use.


There are no contraindications for the use of SYNANTHIC Bovine Dewormer Suspension, 22.5%, in cattle.

Shake well before use.


Store at or below 25°C (77°F). Brief excursions are permitted up to 30°C (86°F). Do not freeze.

Restricted Drug (California) – Use Only as Directed

© 2019 Boehringer Ingelheim Animal Health USA Inc. All rights reserved.

SYNANTHIC and the Cattle Head Logo are registered trademarks of Boehringer Ingelheim Animal Health USA Inc.



Marketed by:
Boehringer Ingelheim Animal Health USA Inc.
Duluth, GA 30096

Principal Display Panel – Container Label 500 mL

NDC 0010-3832-01


(oxfendazole oral suspension)

Bovine Dewormer Suspension, 22.5%

For Animal Use Only

Net Contents: 500 mL

Approved by FDA under NADA # 140-854

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