Core Vaccines

The American Veterinary Medical Association defines core vaccines as those that:

  • protect diseases endemic to a region
  • protect from diseases with potential public health significance
  • are required by law
  • are vaccines against diseases that are virulent/highly infectious, and/or pose a risk of severe disease

Core vaccines have clearly demonstrated efficacy and safety, and thus exhibit a high enough level of patient benefit and low enough level of risk to justify their use in the majority of patients.

The following equine vaccines meet these criteria and are identified as ‘core’ by the American Association of Equine Practitioners:

  • Tetanus
  • Eastern/Western Equine Encephalomyelitis
  • West Nile Virus
  • Rabies

Tetanus Toxoid:

Tetanus is a disease caused by a specific toxin of Clostridium tetani. Horses are among the most sensitive to the harmful effects of the toxin.  Clinical signs observed with the disease include spasmodic contractions and rigidity of some or all of the voluntary muscles, especially of the face, neck, and jaw (hence its nickname "lockjaw"). The bacteria are present throughout the environment and enters the body through wounds. The vaccine is very effective and administered once yearly. The vaccine is boostered in case of laceration, surgery, or penetrating wounds.

Eastern & Western Encephalomyelitis

Encephalomyelitis is caused by a virus that is transmitted by mosquitoes. The virus causes inflammation of the brain and spinal cord.  The vaccine is very effective against the disease. In Florida, we recommend vaccinating initially with 2 doses 3-4 weeks apart with boosters every 6 months thereafter.  For foals born to vaccinated mares, we recommend vaccinating with 2 doses 3 weeks apart beginning when the foal is 6 months old. 

West Nile Virus

West Nile virus is also transmitted by mosquitoes, and like the encephalitidies above, it causes inflammation of the brain and spinal cord.  We recommend initially vaccinating adults horses with 2 doses 3 weeks apart before the beginning of mosquito season, usually in March.  For foals born to vaccinated mares, we recommend vaccinating with 2 doses 3 weeks apart beginning when the foal is 6 months old.  Foals born to nonvaccinated mares, should be vaccinated with 3 doses 3 weeks apart beginning at 3 months of age.


Rabies is a viral disease that affects the nervous system of mammals. It is transmitted through contact with the saliva of infected animals. It is 100% fatal. The vaccine is given once yearly and is very effective.

Risk-Based Vaccines

Vaccines in this category may be included in your program depending on several factors, including the age of your horse, the location of your farm, and your plans to travel with your horse to shows, trail rides, or athletic events.  Commonly used vaccines include:

  • Equine Influenza
  • Equine Herpesvirus (Rhinopneumonitis)
  • Potomac Horse Fever
  • Strangles


Similar to influenza in humans, equine influenza is a virus that causes high fever and respiratory infection. The vaccine is not 100% effective. Horses travelling to shows, trail rides, sales, athletic events, etc. should be vaccinated every 3 months. Horses that do not travel should be vaccinated every 6 to 12 months.


Rhinopneumonitis is a herpes virus which causes respiratory infections, abortions, and inflammation of the spinal cord. The vaccine is not 100% effective and does not protect against the neurologic form of the disease.  Pregnant mares should be vaccinated at 3, 5, 7 and 9 months from the breeding date using a killed product.  Horses that are travelling to shows, races, sales, etc. should be vaccinated every 3 months. Pleasure horses that do not travel should be vaccinated every 6 months.

Potomac Horse Fever

Also known as Equine monocytic ehrlichiosis is caused by Neorickettsia risticii.  This is a seasonal disease, occurring late spring through late fall (majority of cases in July, August, and September).  Clinical signs can vary but include, fever, diarrhea, laminitis, and mild colic.


Strangles is a bacterial disease caused by Streptococcus equi. It is highly contagious and causes high fever, abscessed lymph nodes, and a respiratory infection. Once they are through the initial infection, horses may develop guttural pouch infections, sinus infections, purpura hemorrhagica, laryngeal paralysis, and bastard strangles weeks to months after apparent recovery.  There is an intranasal vaccine which is more effective than the intramuscular vaccine. The vaccine is given once a year except in endemic barns (that have frequent outbreaks) where twice yearly vaccination is recommended.

Other vaccines are also available. If you have questions about any of the vaccines mentioned above, or others you have heard about, schedule an appointment and we can work together to create a vaccination program that best fits your horse(s). It is important to remember that not all vaccines prevent disease, in fact, many work to decrease the severity of the disease if it is contracted.

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