Eastern-Western-Tetanus Vaccine for Horses

The EWT vaccine protects your horse from 3 diseases that can be fatal to your horse. This is the most important vaccine for your horse to get every year.

EWT Vaccine for Horses on Princeton Veterinary Hospital. The EWT vaccine protects your horse from 3 diseases that can be fatal to your horse. This is the most important vaccine for your horse to get every year.

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Eastern-Western-Tetanus Vaccine for Horses

There are a few routine vaccines that we recommend for horses. The vaccine for Eastern-Western-Tetanus is the most important for your horse to receive every year. This vaccine is sometimes called a 3-way vaccine, or a EWT vaccine. The EWT vaccine protects against 3 different diseases in one shot.

Eastern Equine Encephalitis

Eastern Equine Encephalitis (EEE) is the “Eastern” part of the vaccine. EEE is a virus transmitted by mosquitoes, and causes neurologic (brain) disease. EEE is sometimes also called “sleeping sickness” because horses with EEE look very sleepy. EEE can be managed at a specialty care facility, but it has a very poor prognosis and is often fatal. If it can be treated, it is at a large cost with unpredictable results. EEE is very easy to prevent with a yearly vaccine.

Western Equine Encephalitis

Western Equine Encephalitis (WEE) is the “Western” part of the vaccine. WEE is very similar to EEE. WEE is another virus, also transmitted by mosquitoes, that also¬†causes neurologic (brain) disease. The prognosis for WEE is also very poor, and this disease is usually fatal. Just like EEE, WEE is very easy to prevent with this yearly vaccine.


Tetanus is the third disease this vaccine protects against. Tetanus is caused by toxins produced from the Clostridium tetani bacteria. This bacteria grows in the dirt. Animals (and people) are most commonly infected with tetanus through a cut, scratch, or other wound. Any mammal can be infected with tetanus, but horses are more sensitive than most other animals. Tetanus is also called “lockjaw” because it causes severe muscle stiffness. Tetanus can be treated if it is caught early and handled aggressively. Often, horses infected with tetanus die because they are unable to eat or drink. Tetanus can also be prevented with this yearly vaccine.

Because both EEE and WEE are transmitted by mosquitoes, we recommend getting your horse’s vaccines boostered every spring. This will help their immunity be at it’s peak when they are most likely to be bitten by mosquitoes. If your horse is injured and has an open wound or cut, your veterinarian may recommend that he gets a booster of his EWT vaccine to be sure that he has adequate protection against tetanus.

Other Recommended Vaccines

In addition to the EWT vaccine, we also strongly recommend that every horse be vaccinated against West Nile Virus. The American Association of Equine Practitioners also recommends a rabies vaccination for every horse. The rabies vaccine is a requirement for any horse participating in 4-H shows in Indiana. If your horse will be traveling, competing, or spending time with other horses, your veterinarian may also recommend a vaccine against influenza and rhinopneumonitis.

Are your horses up to date on their annual examination and vaccines? Getting an annual examination by your veterinarian is another important part of keeping your horse healthy. If you haven’t gotten your horses their spring shots yet, call us to schedule a farm call, or bring your horses in for their annual examination and vaccines.

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