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Synovex Plus

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

Synovex Plus

This treatment applies to the following species:
Company: Zoetis

(trenbolone acetate and estradiol benzoate)

200 mg trenbolone acetate and 28 mg estradiol benzoate


NADA 141-043, Approved by FDA

Synovex Plus (trenbolone acetate and estradiol benzoate) is a growth promoting implant containing 200 mg of trenbolone acetate and 28 mg of estradiol benzoate. Each implant consists of 8 pellets. Ten implants are provided in each cartridge.

NOTE: Synovex Plus is not better for increased average daily gain than Synovex Choice (100 mg trenbolone acetate/14 mg estradiol benzoate) in steers fed in confinement for slaughter. Studies have demonstrated that the administration of Synovex Plus can result in decreased marbling scores when compared to non-implanted steers and heifers.

DOSAGE: One implant (eight pellets), containing 200 mg of trenbolone acetate and 28 mg of estradiol benzoate, is administered to each steer or heifer by subcutaneous implantation in the middle one-third of the ear.

The ten-dose cartridge of Synovex Plus is designed to be used exclusively with a Synovex implanting device.




Synovex Plus Caution

Bulling, vaginal and rectal prolapse, udder development, ventral edema and elevated tailheads have occasionally been reported in heifers administered Synovex Plus implants.

Directions For Use

Implant complete contents of one cartridge cell per steer or heifer. Approved implantation technique is fully described in the fold-out carton section.

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

How To Implant Synovex Plus® Pellets

For Use With Any Synovex Gun.

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. Care should be taken to insure the hands of the person administering the implant are clean and only sanitary instruments are used.

Synovex Plus (trenbolone acetate and estradiol benzoate) is recommended for steers and heifers fed in confinement for slaughter. When properly administered, Synovex Plus implants increase rate of weight gain and improved feed efficiency in steers and increase rate of weight gain in heifers. Do not use in veal calves. Effectiveness and animal safety in veal calves have not been established.


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

Use product before the expiration date printed on the label.

Once the pouch is opened, unused product may be stored in the end-folded pouch (away from light) for up to six months under refrigerated conditions 2°-8°C (36°-47°F) or at room temperature 20°-25°C (68°-77°F) with excursions between 15°-30°C (59°-86°F) for up to one month.


Not for use in humans. For animal use only. Not for dairy or beef replacement heifers. Implant pellets in 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.

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

Restricted Drug (California)-Use Only as Directed.

Step 1 Loading The Sx10 Gun

Load the SX10 gun following the directions outlined in the instruction manual accompanying each SX10 gun.

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 SX10 gun 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. Holding the SX10 gun 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 SX10 gun 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. Do not withdraw the needle, but allow the automatic needle retractor to release the pellets. This will allow the pellets to be deposited in a straight line in the path of the retracted needle.

Step 6 Inspection

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

Re-cock the gun by grasping the barrel with your left hand and lifting the cocking bolt with your right hand. Fully retract the bolt to the rear of the device. Then, return the bolt forward to its locked position. Disinfect the SX10 gun needle in a germicidal solution. The SX10 gun is now ready to implant the next animal.

NET CONTENTS: One pouch contains ten 10-dose cartridges (100 implants).


Each Cartridge Contains 10 Rows of 8 Pellets

IMPORTANT: Read ALL sides of carton

Manufactured By A Non-Sterilizing Process

Distributed by: Zoetis Inc., Kalamazoo, MI 49007



NAC No.: 3690413.0

Telephone:   269-359-4414
Customer Service:   888-963-8471
Every effort has been made to ensure the accuracy of the Synovex Plus information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the US product label or package insert.

Copyright © 2019 Animalytix LLC. Updated: 2019-09-30