Now is the Time for Lyme and EWT-WNV Vaccinations for Horses

Lyme disease is becoming more and more common in humans, dogs, and horses in our region.  It is spread by ticks and there are two primary ways to counter infection: 

  1. Avoid tick bites (use tick repellents) and remove ticks within 12 hours of attachment,
  2. Vaccinate against Lyme disease, when possible.

There are several Lyme vaccines labeled for dogs, one of these vaccines has been used fairly extensively in horses and does not interfere with laboratory test results.  As a veterinarian, I am allowed to use vaccines in an extra-label fashion, meaning that I may use a dog vaccine in a horse if deemed that the benefit of vaccination outweighs risk. Current research suggests that horses differ from dogs in their response to Lyme disease, as most will not become ill. But for the horses that do become ill with Lyme disease, treatment is expensive (upwards of $500), and can result in loss of performance during a show season. The vaccine does not prevent the disease completely, but it does significantly reduce the severity of illness and the associated costs.

Due to rising concern about the disease in horses, I strongly recommend vaccinating them.

  • I can utilize a canine vaccine that has been shown somewhat protective in horses. The vaccine is administered once, then boostered at 3 weeks, and again at 3 months. Based on current research, the protective effects of the vaccination are short lived, requiring frequent (every 6 month) vaccination after the initial series of 3 vaccines are given. (A scientific overview of Cornell University’s pony studies on Lyme treatment and vaccination: The cost per vaccine dose is $42, as of March 4, 2019.  
  • Because the vaccination initially requires a series of three visits, it can be costly. Try coordinating your schedules with nearby friends so that your call charges may be reduced by arranging back-to-back appointments.  A single call charge can be split between multiple owners at one site.
  • Due to concerns about reactions, I will work with the owners to decide what is the best vaccination plan for each individual horse. For horses that are prone to allergic reactions, I will NOT administer the Lyme vaccine at the same time as other vaccinations. There is currently no equine vaccination for Lyme disease and I am utilizing a canine vaccination off-label.

Horses that were already vaccinated for Lyme disease last year need to be given a booster dose this year, preferably a minimum of 2 weeks before ticks become active, which is often in mid-March.  From here forward, horses that were vaccinated for Lyme previously are recommended to have a booster every 6 months to maintain protective immunity throughout tick season. If finances just won’t reach to cover that expense, I strongly recommend a single booster dose every year in late February / early March, after the initial series.

Horses (and ponies, donkeys, etc.) should also receive their EWT-WNV vaccine boosters now. This vaccine protects against Equine Encephalitis (EEE and WEE), Tetanus, and West Nile Virus. EEE and WNV are carried by mosquitos, thus all Vermont horses are at-risk.  They cause severe illness with neurological symptoms, are indistinguishable from each other on clinical presentation (and indistinguishable from one form of Lyme disease (!). Both cause severe illness and EEE and Tetanus are fatal.

Various other vaccines may be recommended for your horses at this time or over the course of the year. Call Dr. Johnson for a consult and to schedule an appointment!


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