Dr. Victor Cortese presented tips for proper vaccine use in cattle to the AABP New Graduate Conference in Columbus, Ohio in early 2019. Cortese is recognized as a leading expert in the field of dairy cattle immunology. Following are some good thumb rules from his talk.
    Do not give injectable vaccines to calves less than 7 days old, except for Clostridium perfringens products, and preferably do not inject vaccines within the first sixty days. There are reports of calf deaths due to herpes virus hepatitis following vaccination in the first week of life. Mounting an immune response takes energy, and baby calves have little reserves. Injecting vaccines early in life may make calves susceptible to other disease. Intranasal vaccines are safe in very young calves, however.
    Do not vaccine cows with injectable vaccines within the first 30 days after calving. While vaccines in this period are not likely harmful, they may not work due to the immunosuppression most dairy cows experience post calving.
    Do not give more than two gram negative vaccines at the same time. There is a heightened risk of reactions when more than two are given. One may see significant milk drops, fever, induced labor (3-5 days post vaccination) in dry cows, early embryonic death, or in the worst case, down or dead cows. Reactions may take up to 24 hours to appear. Reactions to gram negative vaccines are not endotoxin reactions, but rather due to modulants that are present in the vaccines, so vaccines that advertise low levels of endotoxin can still cause reactions.
    Give SRP vaccines and autogenous Salmonella vaccines by themselves. Reactions may occur due to modulants in these products.
    Consider Clostridial vaccines to be one-half gram negative. Clostridial organisms, while not gram negative, do produce their own exotoxin.
    Never use Vibrio/Lepto combination vaccines in Jerseys or Holsteins. These products have been known to cause abortions.
    Avoid injectable vitamins when giving gram negative vaccines. The carriers in these products are reactive, and they may cause abortions when given with gram negatives.
    Booster all vaccines that require a booster. Check the label for proper timing. Animals that have not received a booster are not protected, period.
    Do not give scours vaccines to dry cows (e.g. ScourGuard, Guardian, Scour Bos) within five weeks of calving. While it is not harmful, cows need at least five weeks to develop antibodies in their colostrum.
    If you use Brucellosis (Bangs) vaccine, do not give it with other vaccines. While less reactive than the old strain used years ago, the current RB 51 strain can still make animals sick.
    Observe label slaughter withdrawals. Vaccines have low levels of antibiotics, normally not enough to cause a residue, but there may be concentrated levels in and around the injection site.
    BVD vaccines can be blocked by maternal antibody for extended periods. Herds that do a great job getting colostrum into calves may find that this blocking will last for long periods of time, even 6-8 months after birth. Thus, any vaccine given for protection for reproductive disease should be given after 8-10 months of age. One dose of a modified viral vaccine should be given to all heifers at least 30 days prior to breeding to ensure adequate protection. In total, calves should receive at least two doses of a MLV vaccine up to 30 days before breeding
    While most modified live viral vaccines are safe to use in pregnant cows if the cows were previously vaccinated with the same vaccine within 12 months, Cortese argues there is no compelling reason to do so. Cows that did not get the earlier vaccine might be at risk for IBR abortion, so any boosters given to late lactation pregnant cows should be of the killed variety in case anyone was missed for the first shot.
    Modified live vaccines must be used with 1.5-2 hours of mixing, or 45 minutes of mixing if in sunlight. Killed vaccines begin to lose potency two weeks after a needle is introduced into the bottle, so repeat use of opened bottles is discouraged.
    Change cannulas between calves when administering intranasal vaccines. It is easy to spread pathogens between calves by using a common cannula.
    It is often hard to comply with all of these restrictions when giving vaccines. Sometimes rules have to be bent or broken. However, being aware of the rules is still advisable. For specific recommendations for your farm, be sure to consult with your herd veterinarian.
    Bennett is one of four dairy veterinarians at Northern Valley Dairy Production Medicine Center in Plainview, Minn. He also consults on dairy farms in other states. He and his wife, Pam, have four children. Jim can be reached at bennettnvac@gmail.com with comments or questions.