Bovine Rotavirus-Coronavirus Vaccine, Clostridial C & D and E. coli vaccine

Product Description

The most complete neonatal diarrhea (scours) vaccine available.

BOVILIS GUARDIAN offers the broadest spectrum of antigens associated with major bacterial and viral causes of scours in young calves including rotavirus types G6, coronavirus, Clostridium perfringens types C & D, and Escherichia coli type K99.


This product has been shown to be effective for the vaccination of healthy pregnant cattle to provide passive immunity against neonatal calf diarrhea due to bovine Group A Serotype rotaviruses, enterotoxigenic E. coli pilus type K99, and bovine coronavirus, and enterotoxemia due to C. perfringens Types C & D in calves. Duration of immunity has not been established.

Passive immunity against neonatal calf diarrhea due to:


Importance Of Scours Prevention

Scours can have a detrimental impact on the health and performance of calves. Anytime the intestinal tract is damaged, absorption is affected and performance impaired.

Vaccination timing for pregnant cows is critical to stimulating and optimizing antibodies in colostrum. If cows are vaccinated too early the antibody response may start to fall off prior to the colostrum being made. Vaccinating too late and the colostrum may be made before an antibody response is mounted.

made in the USA

Colostrum Regime Important To Maximize Antibody Transfer

Colostrum intake within the first 12 hours of a calf’s life is important for it to receive the necessary antibodies to fight scours-causing pathogens. Ideally, a calf will get 2 quarts of colostrum within 2 hours after birth and another 2 quarts within 6 hours after birth for the best antibody absorption.

In addition, it’s important to maintain a clean, open environment and reduce crowding and wet areas because they can lead to increased calf stress and exposure to disease agents.


Shake well and administer a single 2 mL vaccination dose by subcutaneous route to pregnant cattle 3 months prior to calving and a single 2 mL booster dose 3 – 6 weeks following initial vaccination. For subsequent calvings, revaccinate with a single 2 mL dose 5 – 7 weeks prior to calving.


1 x 20 mL (10 doses)
1 x 100 mL (50 doses)


Contains Gentamicin and thimerosal as preservatives.


Store at 2°-8°C (35°-46°F). Do not freeze. Use entire contents when first opened. Do not mix with other products. Do not vaccinate within 60 days before slaughter. Transient local reaction may occur at the injection site. Anaphylactoid reactions may occur following use. Antidote: Epinephrine. In case of human exposure, contact a physician.


BOVILIS GUARDIAN is a multiple-antigen vaccine used in pregnant heifers and cows that is efficacious against neonatal calf diarrhea against major bacterial and viral pathogens associated with scours.

Bovilis Guardian cover image

Bovilis Guardian: Scours Detailer 2023

13 beef herd management tips to help prevent calf scours

Help ensure the colostrum your calves receive contains a high concentration of antigen-specific antibodies by vaccinating pregnant cows with BOVILIS® Guardian®


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U.S. only: Merck Animal Health or call 1-800-211-3573
For more information regarding efficacy and safety data, go to
For additional information, please see the product label.

Late pregnancy is an important time to vaccinate your first-calf heifers and cows to protect your soon-to-be newborn calves against the common scours causing bacterial and viral pathogens. This powerful, broad-spectrum vaccine can provide the assurance you need to get your calves off to a good start.

For more cattle-friendly options, see the rest of the
Merck Animal Health vaccine lineup.