Types of Horse Vaccines

Horse vaccines prevent diseases such as West Nile virus, tetanus, encephalomyelitis and influenza, among others. Some vaccinations use inactivated or killed organisms, which when alive cause the virus. When the dead virus is injected into the horse's system, an immune response is stimulated to protect it from live viruses. Other vaccines use a modified live virus that can reproduce but does not cause the disease. This triggers the horse's immune system to build up antibodies. The two types of vaccines are core vaccines, which are given regularly to all horses, and noncore vaccines, which are given only to certain horses in certain situations.

  1. West Nile Virus

    • West Nile virus is a member of the Japanese encephalitis complex of flavi-viruses. It causes swelling of the brain and spinal cord. The incubation period is between 5 and 15 days from the time the horse is bitten by an infected mosquito. A vaccination to prevent West Nile virus is given annually or semiannually depending on risk. The first dose is given at 3 to 4 months of age for foals whose mother was not vaccinated, with subsequent vaccinations given at 5 months and 6 months. West Nile vaccination is a core vaccine.

    Tetanus

    • Tetanus is caused by the bacterium Clostridium tetani. The toxins of the bacterium cause a paralysis in which the muscles become stiff and hard, unable to relax or contract. Dr. Lyndi Gilliam, DVM, states that a tetanus vaccination of tetanus antitoxin is given at the time of a penetrating injury or surgery if the last booster was not administered within 6 months. The tetanus toxoid vaccination is a core vaccine, which is given annually and provides long-acting protection. For foals whose mother was not vaccinated a series is given at 3 to 5 months and a second dose at 6 to 7 months, followed by a yearly booster.

    Encephalomyelitis

    • Equine Viral Encephalomyelitis is a group of six virus diseases of the brain. Encephalomyelitis vaccine is broken down into EEE, WEE and VEE. EEE is given to horses in high-risk areas; WEE is administered to horses in low-risk areas; and VEE is for foals. The vaccine is a core vaccine given annually in the spring, and when there is a threat of exposure VEE is given.

    Influenza

    • Influenza is a severe, acute respiratory disease with a short incubation period of 3 to 4 days. The virus gains entry through the nasal mucosa and attacks the lining of the respiratory tract causing damage to large areas of mucosa. The American Association of Equine Practitioners advises a series of at least three doses for primary immunization of foals. Inactivated boosters are given for yearly boosters. Influenza is a noncore vaccination.

    Strangles

    • Strangles is primarily a disease of the upper respiratory tract. Foals are administered the first dose of the injectable strangles vaccine at 4 to 6 months, a second dose at 5 to 7 months, a third dose at 7 to 8 months, and a fourth dose at 12 months. Strangles vaccines containing M-protein extract, which may be less reactive than whole-cell vaccines. Yearlings, performance horses, pleasure horses and broodmares receive semiannual boosters of this noncore vaccine.

    Rabies

    • Rabies is a viral disease, which affects the nervous tissue of all warm-blooded species. The horse is particularly susceptible to its effects; however, this is a noncore vaccine. The American Association of Equine Practitioners states that rabies modified live virus vaccine is prohibited for horses. Therefore, inactivated vaccinations are given annually and beginning at 3 to 4 months and at 12 months for foals.