Horse vaccinations are vital to keeping your horse safe against certain diseases, but did you know that your horse doesn’t need every single vaccine that is available? The need for some equine vaccinations depends solely on your geographic location and the amount of travel you do with your horse.
According to the American Association of Equine Practitioners (AAEP), there is no mandated program for equine vaccinations. They do, however, recommend a core set of vaccinations for every horse and they recommend others based solely on the calculated risk of infection.
Many new horse owners may feel overwhelmed at the number of vaccinations available for their horses. Fear not! The following breakdown will provide a complete guide to the wonderful world of horse vaccinations. You will be more than prepared the next time the topic of horse vaccinations comes up.
Keep in mind that this article is meant for informational purposes only. You should work with YOUR veterinarian to determine a vaccine schedule appropriate for your herd and your geographic location.
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Equine vaccinations can cause side-effects in some horses. Small amounts of swelling in the injection site and soreness are normal reactions to vaccinations.
Tiredness and fever are also expected reactions that shouldn’t cause much worry but should be monitored. There are some severe reactions to some vaccinations that can be causes of concern.
Severe side-effects to horse vaccines include but are not limited to skin rashes, colic, and anaphylaxis, an allergic reaction that can result in low blood pressure and airway closure.
Most of these severe reactions cannot be predicted if they have not occurred in that horse previously. The risk of severe reactions may increase when multiple vaccines are given at the same time.
You may want to have your veterinarian administer the first set of vaccines to any new horse. This way, if the horse has an immediate, severe reaction, the veterinarian can provide immediate treatment. While rare, a severe reaction could be fatal.
You will need to work with your vet to decide whether to stagger the vaccines if your horse needs more than just the core vaccinations.
Many vets also recommend not vaccinated within a window of 3 weeks if you intend on transporting your horse for any reason. This ensures that any side-effects or adverse reactions are monitored and caught quickly. Some side-effects can be exasperated by the stress of travel. (source)
What You Need to Know About Immunity
Just because you give your horse a vaccination, it does not mean that they are immediately protected against that particular disease. Horses that were previously unvaccinated will need an initial priming dosage.
This means that it will need one preliminary dosage and then a follow-up injection, or booster, a few weeks later. This ‘waiting time’ in between depends on the specific vaccine.
The horse will only be considered relatively immune to that specific illness after the priming dosage schedule is completed. The horse will then need booster shots at intervals recommended by the manufacturer to keep its immunity.
According to the AAEP:
A properly administered, licensed product should not be assumed to provide complete protection during any given field epidemicAAEP, https://aaep.org/guidelines/vaccination-guidelines/principles-vaccination
This means that you should never just assume that your vaccinated horse is adequately protected against a disease and knowingly expose it to that illness.
If you know of a horse that is or appears to be infected with a specific illness, you should keep your horse away from them at all costs. You should also always keep your stables and pastures/paddocks as clean as possible and limit exposure to unfamiliar horses when you can.
Prevention of exposure to illnesses is just as important as vaccinations. It is always better to be safe than sorry.
Modified-Live Vaccines versus Inactivated Vaccines
Two essential types of horse vaccinations exist including modified-live vaccines and inactivated vaccines.
The majority of equine vaccinations on the market are inactivated. This means that the disease’s microbes have been killed before the vaccine was created. They cannot cause the disease any longer, but they can provide antibodies to prevent the disease.
Modified-live vaccines are created with a modified-live disease microbe. This means that the microbes that cause the disease have been modified in a way that prevents them from causing the disease again.
Typically, modified-live vaccines produce a stronger immunological response with fewer doses and there is typically less side-effect associated with them.
An inactivated vaccine typically maintains it effectively longer when stored and is less likely to be contaminated with other pathogens. Both types of vaccines are extremely effective and the availability of one over the other should not prevent you from vaccinating your horse. (source)
Core Vaccines for Horses
As advised by the AAEP, core vaccinations include vaccines that have scientifically shown their effectiveness and are considered safe. These are the vaccinations every horse should get.
Currently, there are 4 different core vaccinations recommended by the AAEP including equine encephalomyelitis, rabies, tetanus, and West Nile virus.
These vaccinations are beneficial to the horse and have a low risk associated with their usage. They are designed to protect horses from certain diseases that are prevalent in most regions and pose the highest potential risk of infection.
Eastern/Western Equine Encephalomyelitis [EEE and WEE]
EEE and WEE are found in the eastern and western sides of North America, respectively. Birds and small mammals carry the disease and it can be transported to horses by mosquitos, as well as horse to horse if one of them is infected.
The risk of death for horses infected with EEE can be up to 75%, while the mortality rate from WEE is less, at around 20%.
Even if a horse survives the infection, they do not emerge unscathed and often suffer severe neurological defects. The inactivated vaccine for these diseases is recommended for all horses and is considered highly effective in preventing the disease.
Rabies is a viral infection can be transmitted to horses by the bites of dogs, raccoons, and other wildlife. The virus inevitably moves to the brain of the infected animal and quickly progresses to fatal encephalitis.
Since this is a preventable fatal disease, the AAEP recommends an annual inactivated vaccination against rabies for all horses. This ensures that they maintain the necessary level of antibodies against the disease.
It is extremely rare for a horse to contract rabies, but part of the reason for that lies in the fact that it is a core vaccine recommended for all horses.
Please note that rabies vaccinations are not approved for use in horses that are pregnant. If you know or suspect your mare is pregnant, you should wait to give them this vaccine until after they foal unless otherwise recommended by your veterinarian.
Tetanus is a highly fatal disease that every horse runs a risk of developing. The bacteria Clostridium tetani live in the intestinal tract of animals and humans.
Once excreted into the environment, it can survive for years. The bacteria can infect a horse through open wounds or exposed tissues.
The AAEP also recommends that the Tetanus vaccine be given to your horse annually to prevent this disease. They also recommend giving this inactivated vaccine again 4-6 weeks before pregnant mare foals due to the trauma of delivering and the inherent risk of contracting the disease. (source)
West Nile Virus (WNV)
West Nile Virus is another potentially fatal disease that is the main cause of arbovirus encephalitis in both horses and humans in North America.
In the past 20 years, over 25,000 horses have been reportedly infected with West Nile virus encephalitis. More than 96 percent of those cases were in North America.
Mosquitos transmit the disease to both horses and humans, as well as other animals. The virus has a 33% mortality rate in horses. Those horses that do survive often suffer debilitating effects on their gait.
The AAEP recommends vaccinating for West Nile virus annually in the spring months before the insect takeover season begins. WNV vaccinations are not approved for use in horses that are pregnant, but it can be given if the risk is so high that it outweighs the negative side-effects.
There are currently 3 different types of WNV vaccines available. You should work with your vet to decide which one is right for your horse.
Risk-Based Vaccines for Horses
These vaccines are recommended for use after a risk assessment is performed by a veterinarian. They should typically only be used if a vet determines that they are needed.
The recommendation for these vaccines will be based on geographic location and the risk of exposure. If you travel often with your horse, more of these vaccinations will be recommended.
Anthrax is a highly fatal disease caused by the bacteria Bacillus anthracis. This bacteria lives in the alkaline soil of certain geographic locations, mainly in the state of Texas.(source)
The modified-live vaccine for anthrax is only recommended for horses that live in these areas. If your horse lives in an anthrax endemic area, it is recommended that they receive this vaccine annually to prevent infection.
The anthrax equine vaccine is not recommended for use in mares that are pregnant. There have been some side-effects shown in young horses as well as miniature horses, so the use of this vaccine in those particular animals should be monitored. (source)
Botulism is an illness caused by the toxic bacteria Clostridium botulinum. Horses can be infected through open wounds or from eating forage that has the toxin in it.
The bacteria causes a blockage of the message transmission from the nerves to the muscles in horses, which causes paralysis and often death.
There are 8 different subtypes of this bacteria, with types A,B, and C being the most associated with outbreaks. Currently, in the U.S., there is only a vaccine available for type B.
This inactivated vaccine is recommended for all horses, however, it is most needed in those residing in areas prone to breakouts like Kentucky as well as the mid-Atlantic states. (source)
Equine Herpesvirus (EHV-1 and EHV-4)
Equine Herpesvirus type 1 and 4 are illnesses that attack the respiratory system in horses. It causes a variety of respiratory-related issues including fever, lethargy, nasal discharge and cough.
Both strains are transmitted through nasal secretions and can cause hidden infections resulting in horses becoming carriers of the disease. This also means that they can experience a recurrence of the disease later on.
While most adult horses experience less severe symptoms and can easily live through an infection, pregnant mares can suffer abortions if infected.
Vaccinations for EHV-1 and EHV-4 are recommended to prevent abortion in pregnant mares. Bi-annual vaccinations are recommended for horses that have a higher risk of exposure, including young horses and those that travel often.
It is important to note that this vaccine can only be expected to help to lessen the effects of the illness, as vaccinated horses can still be infected.
They will, however, experience less severe symptoms if they have been recently vaccinated. There are currently both modified-live and inactivated vaccines available for this disease. (source)
This viral infection is an extremely contagious illness in horses that can be easily prevented. Young horses, those under 5 years old, are more likely to get equine influenza.
Equine influenza is spread from horse to horse through respiratory secretions. The AAEP recommends vaccinations every 6 months for horses under 5 years of age and horses that have common interaction with unfamiliar groups of horses.
Equine influenza is not a hidden disease and you will notice when a horse infected. It is suggested that this illness can be much easier to prevent if all new horses are quarantined for 14 days more when they are brought onto a farm with other horses.
If you only have one horse that never leaves the farm and never is around other horses, this vaccine is not needed. If you travel with your horse or have horses coming and going off of your farm, the use of this vaccine is warranted.
Keep in mind that equine influenza strains are similar to ours, as in they adapt and change over time. It is still possible for your vaccinated horse to get a different strain of the virus.
There are currently 3 different types of equine influenza vaccinations on the market including inactivated vaccines, modified-live vaccines, and the canary pox vector vaccine. Each of these protects against different strains and have different levels of effectiveness. You should work with your vet to determine which one is right for your horse and lifestyle. (source)
Equine Viral Arteritis (EVA)
EVA is a highly contagious illness in horses that is produced by a viral infection known as the equine arteritis virus. It is not typically a fatal disease but it can result in abortions in mares that are pregnant and even death in young horses.
Stallions can even become carriers of the disease and will pass along their carrier status to offspring.
It is transmitted through respiratory secretions so it can be easily spread to horses that live in close quarters. Most infections do not cause any symptoms that can be easily seen, but sometimes it can cause a fever, depression, and nasal discharge.
Vaccinations for this illness are not recommended for pregnant mares. Stallions and mares bred to stallions that are carriers tend to be the horses most often treated with the EVA vaccine.
The AAEP recommends testing first-time vaccination stallions and mares for the antibody before administering the first dosage. They also recommended working with state or local animal health officials on your vaccination program for EVA. (source)
This disease occurs when a horse is exposed to the bacteria Leptospira spp. which is found in the urine secretions of infected horses and other animals.
Leptospirosis can result in uveitis, abortions and renal failure in horses. Transmission is not typical from horse to horse and usually occurs when an open wound or mucous membrane of a horse is exposed to the bacteria.
There is one relatively new leptospirosis vaccine on the market for horses. Annual vaccinations are recommended for horses that may susceptible to the disease. This inactivated vaccine has been found to be safe for pregnant mares that are in their 2nd trimester. (source)
Potomac Horse Fever
Potomac Horse Fever is also called equine neorickettsiosis, a disease that affects horses most often during warm weather. It produces symptoms including diarrhea, fever, laminitis colic and abominable issues.
Infected pregnant mares could abort foals due to the disease, but it is uncommon. It was originally thought to only affect horses living near the Potomac River, hence the name, however, it is now known that it can affect horses of various locations.
If horses tend to become infected in a certain area, it is recommended that horses in that area be vaccinated every 6-12 months to prevent infection.
There currently one inactivated vaccination available for this disease and is often combined with the vaccination for rabies. Note that with this illness, vaccinating a pregnant mare that is infected will not prevent the possibility of abortion. (source)
This is a viral infection that causes severe diarrhea in foals and the risk of death can be high if there is no medical intervention.
Diarrhea in a foal can quickly become life-threatening. With treatment, mortality is usually low for rotaviral diarrhea.
Vaccinations are recommended for pregnant mares as this is the best method of prevention for newborn foals.
The one inactivated vaccine available for use with this illness has been used for over 20 years and is reportedly safe to use. Foals can still develop the disease after 2 months of age, when their resistance decreases, however, the symptoms will be far less severe than foals of unvaccinated mares. Vaccination is not needed in adult horses that are not pregnant. (source)
Snake bites that are venomous pose a great risk to horses in certain areas. Currently, there is only one vaccine available to treat venomous snake bites in horses.
This vaccine mainly provides protection against western diamondback rattlesnake bites, however, it is possible that it can protect against other venoms of snakes including the western rattlesnake, sidewinder, copperhead, timber rattlesnake and the massasauga.
While it may provide limited safety from the bites of eastern diamondback rattlesnakes, this inactivated vaccine does not offer any sort of protection against certain snakes including water moccasins, coral snakes and the Mojave rattlesnake.
It is recommended for horses over the age of 6 months only and is thought to be okay for use in pregnant mares, however, that fact is not advertised on the label.
Vaccinations for horses living in or traveling to areas with high snake populations are recommended every 6 months to maintain protection. (source)
Strangles is a dangerous bacterial infection caused by streptococcus equi. It typically strikes younger horses but it can affect adult horses as well. The disease causes purpura hemorrhagica, an auto-immune response resulting in generalized vasculitis.
Strangles can cause severe pitting edema of the limbs, head and neck which can result in breathing issues. Vaccination is recommended for horses in locations that have had repeated infections of the disease.
Often, a victim of the illness will become a temporary carrier of the disease and will shed the bacteria back into the environment. Transmission can occur from the horse coming in contact with a surface that is contaminated with the nasal discharge from an infected horse, including feed, tack, stalls, water buckets, troughs, and others.
The strptococcus bacteria is especially able to survive in water sources, which often tends to be the source of infection for many horses. It is vital to work with a vet on the vaccination of horses that have possibly been exposed to the illness, as they are more likely to have reactions from the vaccine.
It is recommended that horses receive the vaccination every 6 to 12 months depending on the likelihood of infection. Currently, there are both modified-live and inactivated vaccines available to prevent this disease. (source)
A combination vaccine can innoculate your horse for a variety of diseases all with one shot. This minimizes the number of injections your horse would receive.
Depending on your state, these can usually be ordered online or purchased at a local equine-friendly store. The decision to use combination vaccinations should be discussed with your veterinarian but is pretty common in the equine world.
Note that these vaccines need to stay refrigerated until you use them. Keep in mind that many of these do not include two of the core vaccinations recommended for all horses. This includes the rabies vaccine and the West Nile virus vaccine.
Pay attention to labeling when purchasing combination vaccines to ensure your horse is receiving all of the vaccinations your veterinarian recommended.
Combination vaccines are considered safe to use if you know what you are doing and can administer the injection correctly. If you have never given an intramuscular injection to a horse before, don’t start now. You should work with a veterinarian to learn the correct way to administer intramuscular injections to your horse.
Determining A Vaccination Schedule
Newborn horses do not need to be vaccinated right away. The AAEP has different age recommendations for the exact time to begin the dosage series in a foal. They put out a .pdf foal vaccination chart to help horse owners decide when to give vaccinations.
If the mother was vaccinated, they will pass along some of the antibodies to the foal. If the mother was not vaccinated, you should start vaccinating those foals a little earlier.
For horses that are 1 year old and older, the AAEP recommends beginning their vaccination schedule immediately, depending on when and if they were last vaccinated. For the older horses, they have a .pdf adult vaccination chart with their recommendations.
In either case, you should work with your veterinarian to determine a specific vaccination schedule for your adult horse, yearling or foal. It is imperative to maintain the schedule that you and your vet agree on so that your horse maintains its immunity to these diseases. A simple lapse in booster vaccinations could cause your horse to suffer unnecessarily.
Cost of Horse Vaccines
The cost of horse vaccines varies depending on the specific vaccine, but they typically cost between $20 and $30 each. Veterinarians also often include a consult fee or farm call fee.
Usually, if you have multiple horses needing vaccines at one time, the vet will combine the costs which usually saves some money in the end.
Combination vaccines are typically on the cheaper end of the spectrum with 5-way vaccines costing between $30 and $40 each, while 7-way vaccine combinations are around $48-60 each.
Keep in mind, you will need to purchase a booster shot as well if this is the first time you are vaccinating for those diseases. Although the costs of vaccinations can add up quickly, especially if you have multiple horses, the money you save in the end will be worth it.
The cost of treating these illnesses and the toll it will take on your horse can be astronomical, if not downright devastating. Losing an emotionally-valued horse is a price you don’t want to pay if the illness could have been easily prevented with a simple vaccine.
Maintaining Vaccination Records
It is important that you maintain vaccination records for each horse. If illness does occur, it will help your veterinarian to rule out certain causes.
Keeping an individual record for each horse is a best practice. In the event the horse travels or is sold, a copy of the log can go with the horse.
I have made a FREE .pdf printable horse vaccine record form for your convenience. It is fillable and you can choose between vertical orientation or horizontal orientation. To get your copy, fill out the form at the bottom of this post and it will be emailed directly to you.
Using a log like this, or one of your own design can help you keep good stable management records for your horse and is easily inserted into a stable management binder or folder record-keeping system.
Frequently Asked Questions
Combination equine vaccines are injections that include multiple vaccines in one dosage.
5-way equine vaccines are combination vaccinations that include 5 different vaccines in one shot. They most likely will include vaccinations for equine encephalitis, equine herpesvirus, equine influenza, and tetanus. Sometimes they will include an additional vaccine for West Nile. If you use a 5-way vaccine, always follow the directions on the label concerning when to vaccinate and when to give a booster. You should always consult with a vet before administering any medications to your horse.
7-way vaccines are also combination vaccine injections, but they include seven different vaccines instead of just five. These include vaccines for West Nile virus, equine encephalomyelitis, tetanus, equine influenza and equine herpesvirus. If you use a 7-way vaccine, always follow the directions on the label concerning when to vaccinate and when to give a booster. You should always consult with a vet before administering any medications to your horse.
For certain illnesses, horses need vaccinations every year to make sure that they still carry the antibodies to prevent the disease. While this may seem unnecessary to some, the risks of infections far outweigh the inconvenience and cost of annual vaccinations. Using the information in this guide, you should work with your local veterinarian to determine the correct vaccination schedule for your horse.
Regardless of what you may have heard through the grapevine, not all vaccinations are recommended for every horse. If you live in an area that is not prone to certain bacteria or illness, or if you never travel with your horse, you could be just fine with only vaccinating your horse with the core vaccinations.
For others, depending on their location and travel plans, certain risk-based vaccinations may be needed. In either situation, you should work with your local veterinarian to decide what vaccination schedule works for you and your horse or horses. Always stick to that schedule and make sure that your horse is protected against these diseases.