of the genetic region amplified; the size of the amplified DNA can be measured by the number of base pairs and compared to the number of base pairs that the EHV-1 primers amplified. A match in base pairs seen in the reaction amplified to the primers used indicates a horse has been infected with EHV-1. Samples acquired from susceptible horses exposed to EHV-1 can be determined from a blood test or nasal swab. Although the PCR test has been a gold standard for many years in determining whether one harbors a certain infection, it is time consuming and there is a chance EHV-1 may not be detected in the DNA sample if the horse is in fact infected. This is common among horses that are latently infected where the virus is not actively replicating and therefore producing multiple copies of its genetic sequence. If a horse is in fact infected with EHV-1, treatment options are limited with the use of anti-inflammatory drugs administered either orally or intravenously. Even then, prognosis of the horse results in treatment that may alleviate EHV-1 symptoms presented (if symptomatic), but cannot be used to eliminate infection as no treatment to date has been found to do so. Prevention Vaccines exist to control the virus but not to prevent it. The inactivated vaccine contain a low antigen load and are made to help protect against the respiratory symptoms, the performance of the inactivated vaccines is variable and does not work for all. The modified live vaccine is made to vaccinate healthy horses 3 months or older, to help prevent the respiratory symptoms caused by EHV-1. Vaccinations should be given in 6-month intervals, and different horses will need to be vaccinated at different times. Pregnant mares should be vaccinated during the fifth, seventh and ninth months of gestation, with the inactivated EHV-1 vaccine. Foals should be vaccinated in a series of 3 doses starting at 3 months in 4–6 week intervals. Even though a horse has been vaccinated, infection and clinical disease still continues to occur. New vaccines to help prevent the spread of the virus are being studied. To prevent the spread of EHV-1, there are a few steps that should be taken. Most important is to stop horse movement and transportation; not allowing horses that have been exposed to EHV-1 to be in contact with unexposed horses; and to isolate animals that are showing symptoms