As the days get longer, many horse owners and horse enthusiasts are eager to begin training for the show season or to get out on the trails. But before you load up your horse and haul them to a fun event, you should ask yourself, "Is my horse up to date on their vaccines?"
Have you ever stopped to consider why we vaccinate our horses - or ourselves, or our dogs and cats? Vaccines are meant to create and maintain immunity against specific diseases. In other words, vaccines are meant to reduce an animal's risk of getting sick, and if they do get sick after vaccination, then the severity of the disease should be lessened and they may be less contagious. The vaccine is usually a modified, weaker version of the disease you are trying to prevent. When the vaccine is given to your horse, their body creates antibodies to fight this "mock disease", and these antibodies will stay in the body for a period of time after the vaccination. Now your horse is armed with a defense system ready to go if they do encounter the actual disease!
Vaccines are created for specific diseases for a few different reasons. A disease might have a high fatality rate, such as tetanus. Or a disease might be highly contagious and easily spread from horse to horse, such as influenza or strangles. Finally, a disease may have the possibility to spread across different species (these are called zoonotic diseases), such as West Nile Virus or rabies.
Equine vaccines are categorized by the American Association of Equine Practitioners (AAEP) as either core vaccines or risk-based vaccines. Core vaccines are vaccines that every single horse should receive, every year. Risk-based vaccines are vaccines that you may or may not administer to your horse, depending on a variety of factors (location, travel expectations, odds of exposure, etc).
| Core Vaccines | Risk-based Vaccines |
|---|---|
| Rabies | Equine Influenza |
| Tetanus | Strangles |
| West Nile Virus | Equines Herpesvirus (Rhinopneumonitis) |
| EEE/WEE | Potomac Horse Fever |
| Botulism | |
| Equine Viral Arteritis | |
| Anthrax | |
| Rotavirus | |
| Snake Bite | |
| Leptospirosis |
The short but frustrating answer to this is: it depends! Keep in mind that for previously-vaccinated, adult horses, the vaccines listed above need to be given on either an annual or semi-annual basis in order to be most effective. For example, if your horse received their rabies vaccine in the fall, then they do not need to receive the rabies vaccine the following spring, since the rabies vaccine is given on an annual basis.
The vaccines that SHOULD be given in the spring are the ones that prevent against diseases spread by insects such as mosquitoes. As the weather warms up, insects reemerge, and the risk of being infected by diseases that they carry will increase. West Nile Virus and EEE/WEE are both transmitted by mosquitoes, so these vaccines should be given prior to the start of “mosquito season".
If you are planning on showing your horse or taking them off the farm to public places, then you should consider some of the risk-based vaccines. Strangles, equine influenza, and equine herpesvirus (EHV) are respiratory diseases that are easily spread from horse to horse and are diseases that are routinely seen where there is a high density of horses, like showgrounds. These diseases are also seen at barns where horses routinely come and go, so even if your horse is not leaving the grounds, other horses could contract diseases and bring them back home, where they could potentially infect their stablemates.
You should always consult with your veterinarian to develop a vaccine plan for your horse. Again, ALL horses should receive the core vaccines (rabies, EEE/WEE, tetanus, and West Nile Virus). The risk-based vaccines will depend on if your horse travels, your geographic location, breeding status, and other considerations. Talk with your vet to determine your horse's risk level for each disease; do not simply give your horse every vaccine available, since this could be costly and unnecessary.
Vaccines guidelines do vary slightly between adult horses, broodmares, and foals, as well as for horses that have never been vaccinated. Be sure to follow the AAEP guidelines for your horse's vaccination schedule. Remember that it can take several weeks after giving a vaccine for your horse to be protected, so plan accordingly based on the weather and your travel plans.
For complete, up to date information on equine vaccines, visit the AAEP Vaccination Guidelines.
For information on the diseases that these vaccines protect against, visit the Merck Veterinary Manual.
