Horse Vaccines: A Case Study

Published: February 11, 2013
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I’ve moved my horse Atticus to another barn … again. I added it up. In the last six years, he’s moved six times – poor guy. I have to admit my sympathy is a bit tempered by the fact that this last change was precipitated by his bone-headed behavior towards another horse at his last facility. I was relieved to see that when I introduced him to his new herd mates, a couple of them immediately made it clear they, and not he, were in charge. Despite what his recent behavior might imply, he is actually happier not being at the top of the herd’s pecking order, so it looks like this should work out. Fingers crossed.

As part of this move, I had to dig out his vaccination records to make sure he was up-to-date on everything. This made me realize that as much as I’ve talked about vaccination protocols for dogs and cats in this blog, I’ve never done the same for horses. My bad. Let me use Atticus in an example of how veterinarians determine which vaccines an individual horse should get.

The American Association of Equine Practitioners (AAEP) divides equine vaccines into "core" — those that the majority of horses should get, and "risk based" — those that should be given after a risk-benefit analysis is performed. The AAEP’s guidelines list the following as core vaccines for horses:

  • Tetanus
  • Eastern and Western Equine Encephalomyelitis
  • West Nile Virus
  • Rabies

Atticus got all of those last year. Check.

According to the AAEP, the risk based vaccines for horses are

  • Anthrax
  • Botulism
  • Equine Herpesvirus (Rhinopneumonitis)
  • Equine Viral Arteritis
  • Equine Influenza
  • Potomac Horse Fever
  • Rotaviral Diarrhea
  • Snake Bite
  • Strangles

Atticus’s primary risk factor is exposure to a large number of horses as he and other horses that he has contact with move in and out of boarding facilities, show grounds, etc. Therefore, I also gave him boosters for equine herpesvirus, influenza, and strangles last year. Looking over the rest of the list, I can discount the majority based on his age and lifestyle. He does not need to be vaccinated against rotavirus (he’s not a foal or pregnant mare), Potomac Horse Fever (we don’t see much of it around here, and the vaccine has questionable efficacy), equine viral arteritis (he’s not going to be bred), or anthrax (he’s not pastured in an endemic area).

I’d consider the snake bite vaccine if we did more trail riding in the foothills near us (home to the western diamondback rattlesnake), but those outings are exceedingly rare so we’ll pass on that. The one vaccine I haven’t given Atticus in the past that I now need to consider is botulism. At his new barn, the horses on pasture are sometimes fed from large round bales of hay. This increases his risk for botulism because Clostridium botulinum bacteria can produce their deadly toxin in spoiling hay or dead critters trapped inside bales.

This exercise is a good reminder as to why an animal’s vaccination protocol needs to be reassessed on a regular basis. Things change. Last week botulism wasn’t on my radar screen; now it is.

Dr. Jennifer Coates

Image: Dhoxax / via Shutterstock