Talk to me about EPM antibodies

[shadesofbay3]

hi all -

those who know my posting history know i have had quite the struggle finding the right horse since my heart horse retired, and have gone through two that were not the right fit at all

leading up to current day, i have an absolutely wonderful horse on trial, let’s call her april. april is older, experienced, saintly, and everything i am
looking for in a horse

vet is coming out on tuesday to do a PPE, and i asked the owner last week for her vet records to just look at and also send to my vet for him to look at prior to the PPE - previous owner has had her for 5/6 years

one thing stood out to me on the records was EPM exam/testing

i inquired with owner (we will call her mary) about it and she told me the following-

mary told me that april was in florida and a man wanted to buy a jumper for his daughter but wanted epm testing done, so mary had it done. this was in april 2023, according to vet records. bloodwork came back with her having the antibodies in her blood, and apparently the titers were also high

mary had her treated with marquis. mary told me she was never symptomic and also never has been and i did see on the vet records that she had a neuro exam shortly after and mary said she passed that

mary also said that her vet said that april’s current workload was more indicative of her not being neurological than her passing a neuro exam - she has been showing at 3’6” up to 4’0” at rated shows and has been very competitive

obviously the people in florida didn’t buy her, don’t know if the EPM was the reason

she has been tested multiple times since and still come up with positive with antibodies (which i don’t know if she should since she was treated?) and high titers … i don’t think a test has been done within a year and don’t know if it would be worth doing one with my PPE

so obviously i will discuss all this with my vet but would this turn you off of a purchase?? for a horse that is perfect otherwise? from what i have read online, up to 50-80% of horses have the antibodies but only 1% ever display symptoms… but whats to say she won’t start displaying symptoms out of the blue one day?

[Simkie]

I would want to know:

Which test
How high
What treatment and for how long

Epm is such an insidious thing and interpreting a neuro exam is just so subjective.

If the titer has not reduced despite treatment I would be concerned that it’s a when, not if, big neuro symptoms are coming.

[gailbyrd]

Titers could also be higher because she is being exposed to EPM on a regular basis (ie: EPM is endemic in her stable area). If you know she will be in stabled in an area that doesn’t have EPM, then the titers may come down. Of course you won’t know this until she is stabled in a different location. But high titers do indicate exposure on a regular basis, whether from circulating protozoa in her body or constant environmental exposure.

[FjordBCRF]

In areas where EPM is prevalent, if you tested all the horses in that area, a good lot of them would have positive titers with zero symptoms. Similar with Lyme. There seems to be something different with horses that become symptomatic to EPM vs those that don’t. There is nothing definitive to my knowledge, but it just seems that their immune systems aren’t able to clear it as effectively.

My personal opinion is if you buy a horse from an area with EPM or live in an area with EPM, you may get a symptomatic horse or you may not and it’s a total crapshoot.

When I was going through diagnostics for a knee buckling issue, we had a moderate EPM titer so we did treat with Marquis, but it ended up being his neck.

[shadesofbay3]

did the titers remain the same after treatment? (even though it wasn’t EPM)

[FjordBCRF]

I didn’t test after. The vet didn’t think it was necessary given the pathology found in his neck and his responding to that treatment.

[Simkie]

@shadesofbay3

did the titers remain the same after treatment? (even though it wasn’t EPM)

I’ve retested a few, both horses that presented with “typical” epm symptoms and those that have not, and the titers have all dropped post treatment, testing… oh… 6-9 months ish after completing it.

[OverandOnward]

@FjordBCRF

In areas where EPM is prevalent, if you tested all the horses in that area, a good lot of them would have positive titers with zero symptoms.

This.

EPM may be the KS of the next few years – far more prevalent than most horse people know; often undiagnosed; possible to have a major effect on the horse; treatment is at least somewhat a work in progress.

Kind of shocking that even where EPM is prevalent a lot of vets are not up to speed on it. An antibody test isn’t part of their standard PPE – but IMO, where EPM is prevalent, it should be.

There is no definitive positive / negative test for EPM as far as I know. But if the antibodies are high, it indicates that the horse is fighting it, or was fighting it recently, even though it may be better now. Hard to say which.

As I understand it, EPM can be held at bay if addressed early enough. But for some horses it will never truly be gone. It may be a come & go situation for the lifetime of the horse.

I know of people who have some herbal or other non-veterinary oral ‘remedies’ that they put through their horses annually. Just on general principal.

My current horse has been treated twice for EPM. I also suspect that he may have been experiencing symptoms at an earlier point. He seems to be doing well now.

We have a lot of possums around here.

[anonevent]

I’m not a vet, but I blood tested my horse out of curiosity because other horses in his stable had tested positive. The results were medium-ish, and my vet said that she advised treating for a month (with protozil) since the treatment was safe (though somewhat expensive). I treated out of an abundance of caution.

If you and your vet are concerned and that would be the one deal breaker, I suppose you could ask for a spinal tap.

[shadesofbay3]

did you do bloodwork after treatment? if so, how were levels afterwards?

[Simkie]

@OverandOnward

An antibody test isn’t part of their standard PPE – but IMO, where EPM is prevalent, it should be.

Yeah, I test for both EPM & Lyme when buying. It’s not part of my PPE and doesn’t factor into my purchasing decision but it’s absolutely the first thing I do as the owner.

Not like I buy a lot (at all) but of the two I’ve bought in the past couple years, one came with a WHOPPING EPM titer. Her neuro exam was “normal” although I found her wonky behind when she stepped over the 4" threshold in & out of her stall. Her titer & wonkiness resolved with a round of compounded ponazuril.

I’ve seen articles that call EPM the biggest concern in equine medicine. My own personal feeling is that infected horses can have very, very subtle neuro symptoms and may be called “normal” … until they very much are not, and at that point, there may be irreversible nerve damage. I’ll always treat a significant titer, and will also treat a low one, if there’s anything suspicious about the horse.

It’s such a tough thing, especially when interpreting a neuro exam is so damned subjective.

[shadesofbay3]

so you said you DON’T let it impact your decision? i understand of course that everyone’s risk tolerance is different

my only uneasiness is how her titers have remained high - keep in mind she was only tested once, and i’m assuming it was the full course of the treatment, but that’s info I don’t have yet

she was tested 3x in 2023 (the first time upon her diagnosis) and once last year in 2024 and all times the titers were at the 1:4000 (don’t quote me on that, i believe that’s correct but dont have her vet records in front of me right now)

her PPE is tuesday and i only have her on trial until saturday. i would love to pull blood and see where the numbers are but 1) i dont think i could get results that quickly and 2) i have no reason to think they wont still be high, so really what is the point

i just dont like that they didnt go down at all after treatment because it seems that means she is either constantly being exposed or actively fighting an infection…

also don’t know if i would do a spinal tap, since apparently treatment the same regardless and the CSF can quickly become contaminated…

[Simkie]

@shadesofbay3

so you said you DON’T let it impact your decision? i understand of course that everyone’s risk tolerance is different

I buy cheap horses that do not have neuro symptoms and have not been EPM tested. No, I don’t let it influence my purchasing decision, in part because of the time it takes to come back (which is onerous or untenable with cheap horses that usually move fast) and also in that I see little risk in purchasing a horse with no obvious symptoms that has never undergone treatment. I assume I can treat a titer/subtle symptoms. But I sure want to know about it before it becomes apparent.

A horse with a stubborn titer is a whole different ballgame. You KNOW you might not be able to treat this horse. And you don’t really know what that means about future soundness/ability.

Why was the horse tested in the first place? Why did they retest so frequently? Call me untrusting, but I would be very concerned that the initial test and the repeated retesting indicates that there IS a problem that they were seeking to identify, and solve.

[anonevent]

I tested 6 months later and they were lower, though not gone. I blood test for EPM and Lyme annually now.

When I first spoke to my vet about it, she said I could either treat or try retesting in a few months to compare the results. The risk was that he could become symptomatic by then and it could be hard or impossible to reverse. I just felt more safe trying to stay ahead of it.

[dmveventer]

@shadesofbay3

i just dont like that they didnt go down at all after treatment because it seems that means she is either constantly being exposed or actively fighting an infection…

You can ask your vet, but if she was never symptomatic then her initial titers may never have indicated an active infection so I wouldn’t expect treatment to do much. In many areas horses ARE being constantly exposed to EPM so you can’t always rely on testing, you have to treat the horse in front of you. With no symptoms at any point and given her current show record I wouldn’t be concerned about this.

@shadesofbay3

also don’t know if i would do a spinal tap, since apparently treatment the same regardless and the CSF can quickly become contaminated…

There’s absolutely no reason to do such an invasive procedure on an asymptomatic horse.

@shadesofbay3

but whats to say she won’t start displaying symptoms out of the blue one day?

You could use this argument to talk yourself out of buying any horse, clean PPE or no. You’ll never be able to eliminate that risk. By looking at something actively doing the job you want them to and finding one that allowed a trial period you’ve already reduced your risk by a lot. Both of those would increase my risk tolerance when it came to the PPE itself, and definitely would put her past medical history lower in my list of concerns. You’re not going to find a horse like that without SOMETHING concerning in her history.

I know you’ve had a rough go with your past few horses and are understandably gun shy, but if you’re feeling this anxious about a purchase with so many green flags you may want to consider leasing for a while instead. It sounds a bit like you’re looking for any reason not to pull the trigger. That gut feeling may be worth listening to, or you’ll drive yourself crazy overthinking everything that could possibly go wrong.

[Ghazzu]

@anonevent

If you and your vet are concerned and that would be the one deal breaker, I suppose you could ask for a spinal tap.

While I understand the reasoning behind it, if a buyer asked me to allow my asymptomatic horse to be subjected to a spinal tap, I’d likely decline.

[shadesofbay3]

thank you, because this was what i needed to read.

and actually on the contrary, i am so ready to cut and write a check for her, i just want to make sure i am making the most informed decision. she is not cheap by any means and i know any horse with mileage is going to come with some sort of potential “issue” - and like it has been mentioned, i could buy anything with a clean bill of health and nothing is to say that in a month or 3 or even a year, something could go awry - whether that’s EPM or something else (colic etc) … a PPE is only a snapshot in time

i just don’t want to feel stupid for spending a very large amount of money on a horse without asking the right questions and then feeling like, if something does happen one day, i didn’t do my due diligence and the blame is on me

she is literally the perfect horse for someone like me coming out of the situation i’ve just been through. quiet, consistent, has the miles, etc. stepped off the trailer for her trial and i rode the same day. just a perfect girl

[shadesofbay3]

agree. i’m not in favor of something that invasive that it seems they treat the same way whether it’s CSF or serum

[dmveventer]

DO IT! She sounds lovely and you deserve a nice horse. There will always be issues but you can deal with those as they come up. My horse had a flawless PPE but we’re currently tracking down a frustrating NQR situation, and I still wouldn’t give him up for the world.

[shadesofbay3]

thank you so so much! <3 feel free to send me a DM if you want - i’m more than happy to send pics/videos!! i think we are in the same state/area too