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


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

(amoxicillin intramammary infusion)


Intramammary Infusion

Amoxi-Mast Caution

Federal law restricts this drug to use by or on the order of a licensed veterinarian.

Amoxi-Mast (amoxicillin intramammary infusion) is specially prepared for the treatment of bovine mastitis in lactating cows.


Amoxi-Mast is a stable, nonirritating suspension of amoxicillin trihydrate containing the equivalent of 62.5 mg of amoxicillin per disposable syringe. Amoxi-Mast is manufactured by a nonsterilizing process.

Amoxicillin trihydrate is a semisynthetic penicillin derived from the penicillin nucleus, 6-amino-penicillanic acid. Chemically, it is D(-)-α-amino-p-hydroxybenzyl penicillin trihydrate.

ACTION: Amoxicillin trihydrate is bactericidal in action against susceptible organisms. It is a broad-spectrum antibiotic which is effective against common infectious mastitis pathogens, namely Streptococcus agalactiae and penicillin-sensitive Staphylococcus aureus.

In vitro studies have demonstrated the susceptibility of the following strains of bacteria: α- and β-haemolytic streptococci, nonpenicillinase-producing staphylococci, and Escherichia coli. Susceptibility has not been demonstrated against penicillinase-producing bacteria, particularly resistant staphylococci. Most strains of Pseudomonas, Klebsiella, and Enterobacter are resistant. The clinical or subclinical significance of these in vitro studies is not known.

Amoxi-Mast Indications

Amoxi-Mast is indicated in the treatment of subclinical infectious bovine mastitis in lactating cows due to Streptococcus agalactiae and penicillin-sensitive Staphylococcus aureus. Early detection and treatment of mastitis is advised.


Milk taken from animals during treatment and for 60 hours (5 milkings) after the last treatment must not be used for food. Treated animals must not be slaughtered for food purposes within 12 days after the last treatment.

PRECAUTION: Because it is a derivative of 6-amino-penicillanic acid, Amoxi-Mast has the potential for producing allergic reactions. Such reactions are rare; however, should they occur, the subject should be treated with the usual agents (antihistamines, pressor amines).

Dosage and Administration

Milk out udder completely. Wash udder and teats thoroughly with warm water containing a suitable dairy antiseptic. Dry thoroughly. Clean and disinfect the teat with alcohol swabs provided in the carton. Remove the syringe tip cover and insert the tip of the syringe into the teat orifice. Express the suspension into the quarter with gentle and continuous pressure. Withdraw the syringe and grasp the end of the teat firmly. Massage the medication up into the milk cistern.

For optimum response, the drug should be administered by intramammary infusion in each infected quarter as described above. Treatment should be repeated at 12-hour intervals for a total of 3 doses. At the next routine milking after the last dose, the treated quarter should be milked out and the milk discarded.

Each carton contains 12 alcohol swabs to facilitate proper cleaning and disinfecting of the teat orifice.

How Supplied

Amoxi-Mast is supplied in cartons of 12 single-dose syringes with 12 alcohol swabs. Each 10-mL, disposable syringe contains amoxicillin trihydrate equivalent to 62.5 mg of amoxicillin activity.

Do Not Store Above 24°C (75°F)

Approved by FDA under NADA # 055-100

Manufactured by:

G.C. Hanford Mfg. Co., Syracuse, NY 13201

Copyright © 2022 Merck & Co., Inc., Rahway, NJ, USA and its affiliates.

All rights reserved.

Rev 10/2022

INS15427 04

CPN: 1047233.5

Intervet Inc.

126 E. LINCOLN AVENUE, PO BOX 2000, Rahway, NJ, 07065
Customer Service:   800-521-5767
Technical Service (Companion Animal):   800-224-5318
Technical Service (Livestock):   800-211-3573
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Copyright © 2024 Animalytix LLC. Updated: 2024-02-27