Vaccination is an integral part of your horse’s health care program.  There is no standard protocol that is suitable for every horse, and individual programs should be developed with your veterinarian.  Vaccinations are given via an intramuscular injection or an intranasal spray.  They help to prime the immune system to react promptly when the horse is exposed to an infectious agent.  There is no guarantee that vaccinating will prevent all disease, but doing so helps minimize the risk of infection and may decrease the severity of symptoms if the animal does become sick.  Ideally, all horses in a group should receive vaccinations on the same schedule when possible.

Basic guidelines to follow for adult horses in West Central Florida (Foal and Broodmare recommendations differ and will not be covered here):

Core vaccines, as defined by the American Association of Equine Practitioners (AAEP), protect against diseases that are endemic to a region, are highly virulent/contagious, pose a risk of severe disease, those having potential public health significance, and/or are required by law.  Core vaccines have clearly demonstrated efficacy and safety, with a high enough level of patient benefit and low enough risk to justify their use in all horses.

  • Eastern Equine Encephalitis and Western Equine Encephalitis (EEE/WEE) are transmitted by mosquitoes to horses and humans from wild birds or rodents.  Horses and humans are “dead end hosts” for this disease and cannot pass it on to others.  Infection causes fever and neurological symptoms with a death rate of 70-90%.  All horses should be vaccinated for EEE/WEE in the spring, prior to mosquito season and again in the fall (every 6 months).
  • West Nile virus is also transmitted by mosquitoes.  It causes neurological symptoms such as change in mentation/behavior, staggering, loss of coordination, and muscle tremors.  The death rate for infected horses is about 33%.  Horses should be vaccinated for West Nile Virus twice yearly.
  • Tetanus is caused by Clostridium tetani, an anaerobic bacteria found in the soil and manure of horses.  This bacteria can infect a horse through open wounds or lacerations.  Signs of Tetanus in horses include stiffness, rigidity, third eyelid prolapse, and “lockjaw”.  Severe cases may not be able to eat or drink and may die or require euthanasia.  All horses should be vaccinated annually for Tetanus and boostered immediately if they sustain a wound or undergo surgery more than 6 months after receiving their last Tetanus vaccination.
  • Rabies can be transmitted to horses through the bite of an infected animal.  It results in progressive neurological disease and is fatal in all cases.  It can be transmitted from infected horses to humans.  Annual vaccination for Rabies is recommended.

The AAEP categorizes the following as Risk-Based Vaccines:

  • Equine Influenza is one of the most common causes of infectious respiratory disease in the horse.  The virus is highly contagious and is transmitted by inhaling respiratory secretions from an infected horse.  The most common signs are fever, dry cough, nasal discharge and decreased appetite.  Horses younger than 5 years of age or those exposed to a large number of other horses through showing or transport are most susceptible.   Most horses recover in two to three weeks with supportive care.  Vaccination for Equine Influenza is recommended every six months, or more frequently (every 3 to 4 months) in higher risk populations.
  • Equine Herpesvirus type 1 (EHV-1) and equine herpes virus type 4 (EHV-4)may cause upper respiratory infections (Rhinopneumonitis) in horses.  Fever, nasal discharge and cough are common symptoms of EHV infection.  EHV-1 can also result in neurologic disease, abortion, and foal death.  EHV-1 and EHV-4 are transmitted through the air or by direct contact with infected nasal secretions on buckets, water troughs, or in drinking water.  Vaccination is not effective in preventing the neurologic form of EHV-1.  Adult horses should be vaccinated for EHV-1 and EHV-4 (Rhino) at least every 6 months to reduce the severity of clinical signs and spread of respiratory disease.  The duration of immunity is short (2 to 4 months).  Horses in higher risk populations may be vaccinated more frequently.

Additional vaccines for Strangles (Streptococcus equi) and Potomac Horse Fever are also available.  Please discuss your horse’s needs with your veterinarian so an individual vaccination program can be designed specifically for your animal.