From Efficacy to Reactions, Here's What to Expect from Horse Vaccines

Veterinarian vaccinating a horse.
Veterinarian vaccinating a horse. Kondrashov MIkhail Evgenevich

Newsdate: Monday, June 2, 2022 - 11:35 am
Location: DULUTH, Ga

Each spring, horse owners are encouraged to schedule a wellness exam with their veterinarians that often includes annual vaccinations. Vaccinations can be put into two categories: core vaccines, used to protect horses against diseases that every horse is at risk of contracting (such as West Nile virus, Eastern and Western encephalitis, tetanus and rabies), and risk-based vaccines.

Horse splashing drinking water on a hot day.

Veterinarian vaccinating horse with aide of intern

Not all vaccines are created equal, so veterinarians are the best resource when choosing the right vaccine for your horse.
© 2013 by Karin Belgrave New window.

The latter are often recommended based on a horse’s geographic location, occupation and traveling status.

One of the most critical health decisions a veterinarian and horse owner can make is choosing the right vaccine. Bob Stenbom, DVM, Senior Equine Professional Services Veterinarian with Boehringer Ingelheim, explains what should be considered when choosing a vaccine.  

“Efficacy is a vaccine’s ability to protect against a certain disease challenge,” says Dr. Stenbom.  “It can vary, and can be based on the time elapsed since the previous exposure to that vaccine, and how well the initial series of vaccines were given to the horse."

"It also depends on how intense or prevalent the disease is in the horse’s geographic area, among other things.” Some horses that compete or perform are required to be vaccinated regularly to minimize outbreaks. Click here for a full listing of vaccines that meet USEF regulations.

All licensed equine vaccines have to meet minimum USDA requirements, but some vaccines outperform others in real-world use. At the end of the day, not all vaccines are created equal.  This is why it can be very difficult for horse owners to assess the efficacy of vaccines on their own. Veterinarians are the best resource when it comes to choosing the right vaccine for your horse.  

Risk Factors and Reactions

According to Stenbom, after a vaccine is administered to a horse, a variety of sensitivities may be observed. However, most mild side effects are normal.

He says, “I like to tell horse owners to think about themselves and what they experience after receiving a vaccination. Transient soreness at the injection site, feeling lethargic and a mild, transient fever are not uncommon side effects.”  

Vaccinations can also temporarily affect a horse’s movement. “Vaccinations are often given in the muscles of the neck, so any amount of discomfort there can be amplified or exaggerated,” adds Dr. Stenbom. “It affects a horse moving its head up and down, and also the locomotion in its front limbs. It can look a lot worse than it is.” 

Horse owners should consult their veterinarian if they are unsure about any side effects a horse may be experiencing after vaccination. Excessive fever, swelling, and/or soreness at the injection site should be reported.

For more information on vaccine options, as well as tailoring your vaccination program to meet the needs of your horse, talk to your veterinarian or visit

Press release by Boehringer Ingelheim

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