Horse Care: Sticking to It

An overview of AAEP recommended vaccination guidelines

story by Hope Ellis-Ashburn

While you may be well-versed on the American Association of Equine Practitioners’ core—and, in some cases, risk-based—vaccination recommendations, you may find that you are less knowledgeable about other parts of their recommended vaccination protocols. Becca Davis, DVM, an associate veterinarian with Scenic City Veterinary Services in Dayton, Tenn., offers her advice on getting the most coverage out of your horses’ vaccinations.


Choosing vaccines

To begin, it can be helpful to understand how veterinarians arrive at their vaccination recommendations.

“Most of the time, the core vaccines are the ones that I recommend all owners give because the risk for the diseases they help protect against are higher regardless of whether that horse is staying in the field or traveling,” Dr. Davis said. “These are the diseases that are typically carried by a vector—such as a mosquito—or by wild animals, such as rabies. The risk factors there are high for all horses.”

Beyond that, Dr. Davis takes into consideration what the horse will be used for and any additional concerns the owner may have about their horse’s exposure to disease.

The most common types of vaccines that horse owners will observe are killed vaccines, which expose the animal to a killed form of the causative agent so that it can form a response to it without becoming infected; and modified live vaccines, which contains a living virus—as the name suggests—but the virus has been altered so that it is unable to infect or attach to cells yet still able to replicate and confer protection.


Levels of protection

It can also be helpful to keep in mind the level of protection that owners can reasonably expect vaccinations to provide. Some vaccines, like those administered to humans, provide only partial protection while others give more complete coverage.

“The rabies vaccine does not prevent horses from getting it,” Dr. Davis explained. Instead, the vaccine aids in preventing it from getting worse. “Other vaccines, like those for eastern and western encephalitis and tetanus, provide good coverage.”

Pre-planning to administer vaccinations two to three weeks ahead of when coverage is needed, such as the start of mosquito season, further increases the likelihood of a given vaccine’s ability to help ward off infection.


Adverse reactions

“Sometimes we can see vaccination abscesses that form or, overall, it just makes the horse lethargic,” Dr. Davis said, adding that other times, the reaction is something less, such as a tender inflamed area at the injection site. “A lot of times these are because we put something in them that their body is reacting to and their immune system is trying to fight off. It means that the immune system is working.”

An abscess, though, is not the same thing. “These can be formed by sticking a needle into a dirty area of the neck,” she said.

While less common, hives are another possible adverse reaction. Keeping track of how your horse responds to vaccinations can help you and your veterinarian decide how to best address the issue. Careful monitoring can also help you determine whether your horse responds best to no or light exercise post-vaccination.


Biosecurity’s role

Beyond recommendations and coverage expectations, the biosecurity measures, or lack thereof, implemented on your farm can have a direct effect on the effectiveness of any veterinarian’s recommended protocols. Of those measures deemed most important, Dr. Davis recommends isolating any horse that is new to your property for a minimum of three to four weeks.

“These horses should also be observed for any nasal discharge or fever to make sure that you are not exposing current horses on the property to any source of contagious disease,” she said. She added that having new horses examined by your veterinarian as quickly as possible and, if necessary, administering initial or booster vaccines to match those of your existing herd can be beneficial.

Dr. Davis further explained that having a high-density population of horses on your farm who share one field and water and feed buckets is another biosecurity deficit that can diminish your horse’s level of protection.


Product labeling

Failing to follow product labeling is another area that can decrease the level of protection that a vaccine gives. Important information that can be found on vaccine labels includes the recommended age to administer the vaccine; the amount; the route, such as subcutaneous or intramuscular, to administer the vaccine; and how the vaccine should be stored. Most vaccines, Dr. Davis advised, should be kept refrigerated to prolong their effectiveness.


Special guidelines for broodmares and foals

For the protection of their foals, the AAEP website recommends that broodmares receive a stepped-up core vaccination schedule with booster shots given four to six weeks before giving birth. Depending upon the need, many risk-based vaccines, except for anthrax, can also be safely administered.

Typically, vaccinations for foals begin at age 4 months and often require a series of boosters. Before that, protection is conferred via colostrum. Like with broodmares, core vaccines and risk-based vaccines can be safely administered. In addition, male foals—or colts—should also receive a single annual dose of the Equine Viral Arteritis (EVA) vaccine.


Establishing a schedule

Some horses—such as those less than a year old, broodmares, and horses that frequently travel—have different vaccination needs. These differing needs include the presence or absence of vaccines normally found on the core vaccination list, or frequent boosters for those horses who regularly travel and therefore experience an increased risk. At other times, for specific reasons, your veterinarian may recommend certain risk-based vaccines. However, Dr. Davis said, if your horse is over a year of age, the core vaccines are typically administered annually.

Many times, the plethora of information to take in—all of which aids your horse in achieving the best possible outcome from an established vaccination protocol—can seem overwhelming. But through extra research and consultation with your veterinarian, you can achieve improved responses that benefit the health of your horse. HB


Hope Ellis-Ashburn is a freelance writer living in Tennessee. To comment on this story, email us at


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