Vaccine Recommendations for Horses

Livestock Update, April 2007

Carrie Swanson, Extension Agent, Albemarle County

Equine facilities should work with their local veterinarian to plan a vaccination program which is tailored to fit the needs of the farm; taking into consideration ages, types, activities and number of horses as well as geographic location.  A backyard facility with two horses which never leave the property is going to require a lower level of preventative care than a large show barn, or horses that are exposed to a transient population.  Local vets can provide information concerning new threats and changes having to do with disease risk in a particular area, and can also update clients on advances in vaccine technology and recommended protocols.

There are two diseases which are endemic in Virginia and should be a part of any vaccination program. The first is Rabies, which as a zoonotic disease, can be transmitted to other species, including humans, and is nearly always fatal.  Considering the close contact we have with our horses and the potential for them to come into contact with wildlife, vaccination is essential.  The second is Tetanus.  Tetanus is an anaerobic bacterium found in the soil, which can cause extremely painful death if it finds its way into an open wound.  Luckily, there are extremely effective, and relatively low-cost, vaccines for both these diseases.

In Virginia horses are also commonly vaccinated for Eastern and Western Equine Encephalitis viruses (EEE & WEE).  Spread by mosquitoes, these affect the brain and spinal cord, causing depression, weakness, ataxia, fever, and difficulty eating.  Another Mosquito borne disease, West Nile Virus, has become a problem in Virginia only in recent years.  Fatal in about 25% of cases, the number of equine cases of West Nile has declined dramatically since the development and widespread use of a vaccine. This serves as a good reminder of the important role vaccines can play in protecting our horses.  When vaccinating for diseases which rely on insects for transmission, timing is everything.  Consult with your veterinarian to find out the best time of year, and whether or not a vaccine should be given more than once a year in your area.

Equine Influenza is a common respiratory infection that affects many horses each year, but that has a low mortality rate.  It is however, highly contagious, and recovery can take weeks or months, keeping horses out of training and competition.  Flu vaccine efficacy can vary depending on the type; and how often you should give the vaccine depends on the amount of exposure your horses encounter.

Another highly infectious disease which affects horses is Equine Herpes Virus I & IV (EHV) also known as Rhinopneumonitis.  Type 1 causes respiratory disease, weak foals and abortion.  Type 4 is usually associated with respiratory disease.  The neurologic form of the disease is rare, but periodic outbreaks do occur.  Pregnant mares require more frequent vaccination.  Vaccination does not protect against the neurologic form, and highlights the need for routine biosecurity measures in our preventative care programs.

Potomac Horse Fever can cause severe diarrhea, laminitis, and abortion.  Although this disease is seen most commonly in farms within close proximity to the Potomac River, vaccination is recommended throughout much of the state.  While it may not provide complete protection, the current vaccine is generally considered to lessen the severity of the disease if horses are exposed.

Other vaccines which may warrant consideration in some circumstances are: Equine Protozoal Myeloencephalitis (EPM), Botulism, Strangles (Streptococcus Equi), and Equine Viral Artertis (EVA).
The American Association of Equine Practitioners’ (AAEP) website for horse owners provides general guidelines for vaccination protocols and education on a variety of subjects: www.myhorsematters.com

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