Vaccines are very important to minimize the risk of infection with potentially fatal diseases, however they cannot prevent disease in all circumstances. The vaccinations that are considered “core” are those with potential public health risks, very highly infectious, common in our region, or required by law. Tetanus, Eastern & Western Equine Encephalomyelitis, West Nile Virus, and rabies are the “core” vaccines. Other commonly requested vaccines include Strangles, Equine Influenza, and Equine Herpesvirus or Rhinopneumonitits. Infrequently, Rotavirus, Equine Viral Arteritis, Botulism, Anthrax, Snake Bite, and Potomac Horse Fever vaccines are administered in endemic areas or for special circumstances.
Tetanus is caused by the bacteria Clostridium tetani which can survive in the environment for many years. It is acquired from punctures, lacerations, surgical incision, umbilicus of foals, and reproductive tract of postpartum mares. Tetanus toxoid vaccines should be given annually to previously vaccinated horses and in a two-dose series to horses that have not been vaccinated or if the vaccination history is unknown. The two tetanus toxoid vaccines should be give four to six weeks apart, followed by annual vaccines.
Eastern and Western Encephalitis (EEE and WEE) are viruses spread by mosquitoes to wild birds and rodents and then to horses. The risk of exposure to EEE and WEE varies from year to year.
Adult horses that have been previously vaccinated should be vaccinated annually. Horses with unknown vaccination history or have not been previously vaccinated should receive a two dose series four to six weeks apart, followed by annually.
West Nile virus is spread from birds to mosquitoes and then to horses, humans, or other mammals. It is the leading cause of encephalitis in the U.S. Adult horses that are current on vaccines should receive annual vaccination in the spring. Animals with unknown vaccination history or previously unvaccinated should receive a two dose series four to six weeks apart, followed by annual vaccination.
Rabies virus causes a neurological disease that is fatal and of public health concern. The virus is acquired via a bite from an infected animal.
Common sources of infection include the raccoon, skunk, fox, or bat. Adult horses both previously vaccinated and unvaccinated should receive a single vaccine annually.
Due to recent outbreaks, Equine Herpesvirus vaccinations have become more common. Both EHV-1 and EHV-4 are spread by aerosolized nasal secretions from infected horses. EHV-1 causes abortion in pregnant mares, weak foals, and neurologic disease. EHV-4 causes respiratory disease in all ages of horses.