Skip to main content

Synovex C

This page contains information on Synovex C for veterinary use.
The information provided typically includes the following:
  • Synovex C Indications
  • Warnings and cautions for Synovex C
  • Direction and dosage information for Synovex C

Synovex C

This treatment applies to the following species:
Company: Zoetis

(progesterone and estradiol benzoate implants)

100 mg progesterone and 10 mg estradiol benzoate per implant


For increased rate of weight gain

This product was manufactured by a non-sterilizing process.

Important: Read ALL sides of carton

Do Not Use In Veal Calves

Not For Use In Humans

For Animal Use Only

For subcutaneous ear implantation only.

Approved by FDA under NADA # 009-576

Synovex C Calf Implants contain two pure steroid hormones, progesterone and estradiol benzoate. This formulation provides a complementary amount of each hormone for maximal growth stimulation. Study the enclosed instructions carefully and use this product only as illustrated.

How To Implant With Synovex® C

(progesterone and estradiol benzoate)

100 mg progesterone and 10 mg estradiol benzoate per implant


Study the following instructions carefully, then proceed step by step, until the technique becomes routine. Many head can be implanted per hour by an experienced team, one member of which should be assigned to do nothing but the implantation. This person should maintain hand cleanliness and use sanitary instruments only.

How Supplied

100 Dose

Synovex® C Implants

Synovex C (progesterone and estradiol benzoate implants) is recommended for use in suckling beef calves up to 400 lbs of body weight. Synovex C is also recommended for improvement in rate of weight gain in steers weighing greater than 400 pounds and fed in confinement for slaughter when used as part of a re-implant program in which an initial Synovex C implant is followed at approximately 70 days by Synovex S. Do not use in veal calves. Effectiveness and animal safety in veal calves have not been established.

Do not use in bull calves intended for reproduction, or in calves less than 45 days old.

Store at controlled room temperature 20° - 25°C (68° - 77°F) with excursions between 15°-30°C (59°-86°F). Avoid excessive heat or humidity.


Not for use in humans. For animal use only. Implant pellets in the ear only. Any other location is in violation of federal law. Do not attempt salvage of implanted site for human or animal food.

A withdrawal period has not been established for this product in pre-ruminating calves. Do not use in calves to be processed for veal.

Synovex C Caution

Bulling, rectal and vaginal prolapse, udder development, ventral edema and elevated tailheads may be reported in calves administered Synovex C implants.

Keep this and all drugs out of the reach of children.

Restricted Drug (California) - Use Only as Directed.

Directions For Use

Implant complete contents of one cartridge cell per calf at each implanting. Approved implantation technique is fully described in the package insert.

NOTE: Never sacrifice careful, clean technique for speed of implantation.

Step 1 Loading The Applicator

Load the applicator following the directions outlined in the instruction manual accompanying each applicator.

Additional information for the individual applicator user guides can be found at:

Step 2 Restraint

The animal must be confined in a restraint mechanism (squeeze chute or head gate). The implant site on the back of the ear should be prepared by scrubbing with a firm bristled brush that has been soaked in a germicidal solution.

Note: If implanting horned cattle, greater safety is provided when the head is controlled by the use of a bull lead (nose tongs).

Step 3 Implant Site

Divide the ear into three imaginary sections as illustrated. The implanted pellets should be deposited in the center one-third of the ear as shown. To accomplish this, the applicator needle should be inserted in the outer one-third of the ear as indicated by the “X” in the illustration. Implanting too close to the head may cause abnormal sexual behavior. Care should be taken to avoid severing the major arteries of the ear.

Step 4 Insert Needle

Grasp the ear with one hand. While holding the applicator firmly with the other hand, penetrate the skin at the point shown by the “X”. Thrust the needle under the skin taking care not to penetrate the cartilage. Ease the applicator forward (toward the base of the ear) until the full needle length is beneath the skin.

Step 5 Pellet Implantation

When the needle is completely inserted, activate the instrument by squeezing the trigger completely. Refer to instructions for individual applicator.

Step 6 Inspection

Check the implant site. If properly administered, the implants should lie in a straight line under the skin.

Re-cock the applicator. Disinfect the applicator needle in a germicidal solution. The applicator is now ready to implant the next animal.

Distributed by: Zoetis Inc., Kalamazoo, MI 49007



Each Cartridge Contains 10 Rows of 4 Pellets.


CPN: 3690403.1

Telephone:   269-359-4414
Customer Service:   888-963-8471
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