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Vaccine Reactions

Updated: Nov 16, 2020

Vaccinations are designed to provide your equine partner immunity against illnesses that are transmitted by other horses or species. Once the vaccine is injected, the body recognizes the virus and creates antibodies to help protect the horse against the specific pathogen. The antibodies that are created remain in the system and help fight off infection if the horse comes into contact with the virus in the future.

If the vaccine is supposed to protect my horse, why is he having a reaction?

A vaccine is composed of antigens, stabilizers, adjuvants, antibiotics, and preservatives. All of the components work together to maintain the integrity of the vaccine, prevent contamination from bacteria, and prolong the duration that the vaccine is good for. Due to all the different components, it is not uncommon for your horse to experience a reaction. While many horses do not have any type of vaccine reaction, some horses may exhibit adverse side effects.

If my horse has a reaction, what should I do?

Common vaccine reactions include swelling and soreness at the injection site, fever, and decreased appetite or energy. The reactions to vaccines that are most often seen are caused by the antigen or the virus in the vaccine. This does not compromise the effectiveness of the vaccination. In the case that your horse experiences a vaccine reaction, nonsteroidal anti-inflammatories, such as Banamine, can be administered. Applying a cold compress to the injection site as well as light exercise will also aid in dissipating any swelling or stiffness. Vaccine reactions are normal and tell us that the vaccine is working properly, however side effects should resolve within 48 hours after vaccine administration. If symptoms persist beyond this time, it is important to consult your veterinarian.

If you have concerns about your horse or the vaccine reaction they are experiencing, do not hesitate to contact your veterinarian directly.


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