Vaccine Guidelines

These guidelines are based on the American Association of Equine Practitioners vaccine recommendations for core vaccines and strongly recommended vaccines (aka vaccines almost all horses should have). Vaccine guidelines are different for foals/weanlings and pregnant mares – these are for adult (greater than one year) non-breeding animals. Vaccines for other diseases certainly exist and may or may not be recommended depending on the individual and the location/intended location of the horse. As always, if you have any questions regarding your horse(s), contact your vet.

Core Vaccinations

Tetanus

Tetanus is caused by the toxin of the bacteria Clostridium tetani. The bacteria lives in the environment and most animals contract it via wounds. The toxin causes severe persistent body-wide muscle contractions. Most horses that develop tetanus are euthanized for humane reasons, though the disease itself may be fatal. Horses should be vaccinated annually. Horses that sustain a wound or undergo surgery 6 or more months after their previous tetanus booster should be revaccinated with tetanus toxoid immediately at the time of injury or surgery.

Note: The severity of the wound does not predict the risk for development of tetanus. Superficial wounds have resulted in clinical tetanus in horses.

EEE/WEE

EEE/WEE are mosquito-transmitted viral based neurologic diseases that are generally very severe and have a high fatality rate. Annual revaccination should be completed prior to mosquito season in the spring. In areas where mosquitoes are active year-round, many veterinarians elect to vaccinate horses at 6-month intervals to ensure uniform protection throughout the year.

West Nile Virus

West Nile virus causes neurologic disease of varying severity. Like EEE/WEE, West Nile is transmitted by mosquitos. Horses should be vaccinated annually in the spring, prior to the onset of the mosquito season.

Booster vaccinations are warranted according to local disease or exposure risk.

Rabies

Rabies is a rare cause of neurologic disease in horses. While the incidence of rabies in horses is low, the disease is invariably fatal and has considerable public health significance. By the time a horse is diagnosed with Rabies often numerous people have been exposed. It is recommended that rabies vaccine be a core vaccine for all horses and should be given yearly.

Strongly Recommended Vaccinations

EHV (Herpes virus)

EHV-1 & EHV-4

Each can infect the respiratory tract that can range in severity from sub-clinical to severe. Symptoms include fever, lethargy, nasal discharge, cough, and anorexia. In foals, it typically occurs in the first weeks or months after birth. Recurrent infections are seen in weanlings, yearlings, and young horses, especially in a training environment where horses are intermixed from various environments. EHV-1 can cause abortion in mares, birth of foals that are weak and nonviable, or neurologic disease secondary to vasculitis of the spinal cord and brain.

With the exception of pregnant mares, it is recommended that the following horses be revaccinated at 6-month intervals:

Horses less than 5 years of age.
Horses on breeding farms or in contact with pregnant mares.
Horses housed at facilities with frequent equine movement on and off the premises, thus resulting in an increased risk of exposure.
Performance or show horses in high-risk areas, such as racetracks. More frequent vaccination may be required as a criterion for entry to certain facilities.

Flu (Influenza)

Influenza is endemic in the equine population of the United Sates and throughout much of the world. Equine influenza is highly contagious and the virus spreads rapidly through groups of horses in aerosolized droplets dispersed by coughing. All horses should be vaccinated against equine influenza unless they live in a closed and isolated facility.

Mature performance, show, or pleasure horses constantly at risk of exposure should be revaccinated at 6-month intervals. Other adult horses can be vaccinated as infrequently as once a year.

Equine Rhinitis A Virus (ERAV)

This disease can affect both the upper and lower airways in horses and can be spread nose to nose through nasal discharge as well as aerosol inhalation. It may be a contributing or exacerbating factor of inflammatory airway disease (IAD) and recurrent airway obstruction (RAO or Heaves).

The vaccine is given annually to semi-annually. A booster is needed 4 weeks after the initial dose is given.