adventures with the vet

Vet Update: Lyme Vaccine

I mentioned last week that my vet had listed consideration for a Lyme vaccine on my invoice from spring shots. I was curious, so I emailed her to ask more.

I wrote:

Hi Alison, 

I’m filing Tristan’s vet paperwork from his shots, and saw your note about the Lyme vaccine. I wasn’t aware that there was one yet for horses! I know my dog gets it every year. 

Is it new, or is it a variation on the dog vaccine? I’d love to learn more. (Mostly out of curiosity; I have never found a tick on Tris up here so I agree with you that it doesn’t make sense if he stays at this farm.)


To which the vet replied:

Hi Amanda. Dr Divers at Cornell started a study a few years ago using the Merial vaccine for lyme in dogs administered to horses. Very good efficacy and safety, study should be out this year. So it is exactly the dog vaccine, but I’ve become quite comfortable using it. 3 doses 1 month apart and then every 6-12 months depending on region.

Which is fascinating and kind of awesome! Years ago, we boarded at a barn that had absolutely ridiculously high levels of tick-borne disease. That was the first time I learned about ehrlichia, which is a vile little disease that every single horse in the barn but Tristan got at least once, many of them multiple times.

But he got ticks quite frequently, and he reacted horribly to them. Giant orange-sized abscesses, weeping puss, hot and painful to the touch. Mostly around his head and neck. I would wash them, treat them with antibiotic cream, and hot compress them endlessly to try and ease his misery a bit. Sometimes he got bute, but it never seemed to make a huge difference.

I always held onto a wholly unscientific theory that Tristan was fighting some kind of infection on the surface. No other horse in the barn reacted that way to tick bites. They just went about their business and then came down with the sudden high fevers that are characteristic of ehrlichia. He blew out those abscesses but sailed past anything deeper. I pulled a Lyme titer on him quarterly just to be neurotic, but he never registered any infection at all. Dumb luck, good constitution, some combination of the two – I’ll never know.

Here’s a good Practical Horseman article about the causes, symptoms, and treatment for Lyme that includes a little bit about the Cornell study at the end.

Here’s another (PDF) article right from Cornell with much more detail and more science.

So: it doesn’t make sense for us right now, but it’s awesome to know that there’s real research and strides being made toward a vaccine. Lyme is horrible, and it’s only going to get more widespread as ticks survive more and more of these mild winters.

10 thoughts on “Vet Update: Lyme Vaccine

  1. Fascinating! The ticks down here are Out. Of. Control. down here already (or at least they were until it suddenly turned into winter again – thinking about, if it gets rid of the ticks I think I can make peace with the current weather). The horses at our barn are getting a round of shots on Friday and I'll be around so I'll be asking my vet about this vaccine!


  2. The barn I boarded at with all those ticks was probably not far from you – in West Boxford. I remember all too well what the ticks are like in MA.


  3. I'm glad there's a vaccine now. A friend of ours had a really bad reaction to a tuck bite recently and had to go into the doctors. The doctor told him that in our area the ticks also bit lizards and the lizards apparently kill the lyme's. Now, if the tick then goes back to a deer or mouse it can get Lymes again, but that's apparently part of why Lymes so much less common here in CA than in new England.


  4. Hmm, the vet will be out Monday to do a bunch of other horses in the barn. I'll have to ask her about it then. Bobby was diagnosed a few years ago, but hasn't really displayed any symptoms since that first year.


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