Please share if he responds, I’d love to know!
I bought a horse that had spent 5 years in New England, living mostly outside. We tested her for Lyme to get a baseline- the Cornell test you send out that tells you about past exposure- and it came back totally negative. No exposure. Vet was like “that can’t be right” and insisted the lab do it again with a fresh sample. Negative again. I’ve caught the vet staring at her pensively several times since.
Okay, here is his response:
"To my knowledge there has not been any papers published or in the works to parse out the differences in either equine or canine. I have attached some links of some of the most recent including Pfizers human trials.
So basics on testing for Lyme infections is a trivalent test OspA, OspC and OspF. Widely accepted, OspF tests for IgG levels in chronic infections based on stable cell membrane proteins. OspA and OspC determine IgM/IgG in acute infections. Acute infections get murky. As stated in papers, OspA and OspC can have cross reactivity to make vaccine related immunity and acute infections tough to determine. I will throw in that there are also some chronic cases that show more OspA/OspC response. So the research is still unclear…and for horses, will likely never become clear. To get FDA approval on vaccines, you need hundreds of case records which in equine is cost prohibitive and tough to do which will never produce an equine exclusive Lyme vaccine. I will also throw in there that SNAP tests can be looking for cell wall components that are not ubiquitous in all infections which is why trivalent testing is the best option.
So some of the concerns with OspA specific vaccines are that they are variant/serotype specific meaning the vaccines are developed based on samples from a narrow selection of clinical specimens and not representative of the spectrum of infectious agents. To date, as seen in the papers, at least 7 serotypes of OspA have been identified to be pathogenic and possibly more than that. So the move to OspA/OspC cross reacting vaccines aka “chimeric or bivalent” was to get as many possible infectious variants by targeting multiple parts of the cell membrane rather than being one variant specific, which was the failing of the early Lyme vaccines. Unfortunately this makes testing not the most sensitive but the best we have.
So in summary, the recombinant/chimeric/whole bacterin vaccines are accepted to be effective against more serotypes of Lyme and generate a wider immune response. While yes can cloud testing, provides better overall protection against Lyme and potentially a stronger immune response, hence our choice to go with Zoetis recombinant vaccine. (FYI Zoetis/Fort Dodge is the veterinary offshoot of Pfizer with the current human trial)."
So, basically it is a risk vs. reward situation - he feels the enhanced protection of the whole-bacterin vaccines outweigh the risk of compromising diagnostics in the future. The Zoetis vaccine is supposed to offer even more protection than the Nobivac in terms of OspC expressions (7 vs. only 1). However, the Nobivac is supposed to offer more protection than the traditional Recombitek. I’m leaning towards Nobivac as a good compromise (and I can get it easily).
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It sounds like he’s unaware of the Cornell paper and also that BI has gotten their EquiLyme approved in Germany. Which is…worrisome.
If you go the Duramune route, testing directly prior to vaccination to confirm status seems especially prudent, since testing post is murky.
Well, my next question is whether or not the lyme vaccine that my horses already got in the fall from this clinic was also the Zoetis. If it was, no point in testing.
That’s certainly worth investigating. I don’t think there’s no point in testing–there’s still going to be a point where active infection will drive the test up beyond what a vaccine would do–but your equivocal range would be larger.
When was the last time you tested, and how does that relate to when you vaccinated?
When I was discussing this with my vet, they test pre vaccination, and then again to confirm the horse mounted a OspA response. If no OspA response, revaccinate. There’s a lot of testing to see where the horse is & how it’s responding (and also to check Lyme infection status.)
I don’t think you want to vaccinate an active Lyme infection (there’s some supposition that vaccinating chronic, active Lyme is one of the things that caused adverse effects with the human vaccine) so it’s important to look & treat if necessary.
My one gelding hasn’t been tested in several years, just vaccinated. The other gelding has never been tested, just vaccinated. My two fillies also never tested, just vaccinated. None are symptomatic/have ever been symptomatic.
I have to caution against treating asymptomatic horses. A friend uses a different vet - he wouldn’t vaccinate prior to testing. The horse tested positive for chronic lyme but was asymptomatic. My vet would have waited a few months and retested to see if the infection was trending down. This other vet started throwing all sorts of antibiotics at this completely asymptomatic horse (2+ years of doxy, minocyline, Exceed) and destroyed the horse’s immune system. He now has chronic sinus infections (fungal and bacterial) and is currently recovering from his fourth surgery with a drug-resistant infection that will not resolve. Not sure if he’ll make it.
Cornell also cautions against treating asymptomatic horses who test positive for chronic lyme - they recommend tracking the numbers and watching for symptoms/large spikes in the titer. The idea is to see if the horse’s immune system can manage it before creating a situation like the one I just described.
I had a gelding with chronic lyme who became symptomatic. We treated him with 30 days of oxytet and then vaccinated him. At the time of vaccination his numbers were trending downwards but weren’t in the acceptable range yet. Post-vaccination the numbers dropped into the “negative for chronic infection” range. I then sold him and yes, I disclosed all this to the buyer and recommended they continue to vaccinate.
So, all of this comes down to a costs/benefits analysis due to the lack of ongoing research and the complexity of the disease itself.
Certainly. But “symptomatic” can be maddeningly subtle. It’s not like it’s a flashing neon sign.
I can’t imagine not having a baseline. Especially when vaccinating, which is a) far from a guarantee of avoiding infection and b) makes interpreting a titer if the horse does pop with potential symptoms more difficult. Not to mention any potential risk vaccinating a positive horse.
We all have our own comfort levels, and what you describe is certainly outside of mine, but I live in an area with a LOT of Lyme, so perhaps not testing is less concerning with less saturation.
Technically, my horse was still “positive” for chronic lyme when we vaccinated him and his numbers dropped into the negative range post-vaccine.
As an aside, I personally think we over-vaccinate in general. For example, we give EWT/WN every year to horses but do we really know how long these vaccines provide protection? I read on one vet’s website that EE/WE and WN really only give 6 months protection but of course no one can back that up that claim with any research. Most vets will concede that tetanus probably doesn’t need to be given every year, but as it is in the EWT combo shots, they just give it. And there is this study out about the rabies vaccine:
Having said all that, the lyme vaccine is one that I don’t skip after treating it in that horse.
Like you said, it comes down to comfort level. I just wish there was more research being done. If anyone comes across anything new, please post.
Uh, there’s quite a lot of study in this area. For example:
This study in eastern & western equine encephalitis vaccine:
This study in equine west nile virus vaccine:
I don’t know why you’d say “of course no one can back up that claim with research” when, yeah, they can.
And yes, of course, a horse can have a “positive” Lyme titer following treatment that’s not indicative of active infection. We’re testing immune response, not infection. Which is why the history is an important piece.
With regard to rabies, until challenge studies are done that demonstrate what titer value confers immunity, erroring on the side of yearly vaccination to guarantee immunity is a whole hell of a lot smarter than assuming immunity and being wrong. Rabies is 100% fatal for the horse, and also zoonotic.
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Every time I’ve asked a vet for research, they tell me that there isn’t $$$ to be made from doing further research beyond what the pharmaceutical companies (who sell the vaccines) put out. Or, they point out that there isn’t a lot of current research available (see my vet’s response below). Further, testing levels of circulating antibodies ignores what is happening at the cellular level in regards to immunity.
One vet told me that the only horse she ever saw die from rabies had been vaccinated within the year while the paper that I linked above found that protective levels lasted for 9 years in one of the samples of horses. I have a vet-tech friend who worked for a vet that wouldn’t vaccinate without titering first and that vet never found a horse in her practice to titer below the protective level for rabies until at least 8-years post-vaccination. My one mare almost died from a rabies vaccine. Every time we vaccinate we stress the horse’s immune system. Further, as that study you just linked pointed out, sometimes the vaccine doesn’t even elicit a protective response. So, this one-size-fits all approach to vaccination isn’t ideal. It comes down to a risk/benefit analysis.
As an aside, my vet responded again and my horses have been getting the Zoetis lyme since 2019. He pointed out: “The general thought was that breakthrough infections or lack of effectiveness as shown in the paper you listed is that most of the early Lyme vaccines were developed based on the Lyme sample they had at the time which may have been one OspA variant specific. Now that it is known that there could be 7+ variants, exposure to others that were not included in the vaccine left patients unprotected. Keep in mind it takes 7+ years for any vaccine to get to the market so the Lyme samples they built the vaccine off would have been late 90’s to early 2000’s when the research into variants has not known.”
I think we can agree that there is certainly more work to be done in regards to research.
Idk, maybe do your own search. Because that’s incorrect.
The amount of irony here is truly remarkable:
AAEP core equine vaccines, rabies, tetanus, EEE, WEE, WNV. Multiple brands of equine vaccine available, FDA approved with required study. Multiple further published studies detailing immune response and duration. Diseases are always or often fatal, rabies is untreatable & directly transmittable to people. All are ugly deaths.
Your take: not enough research, we should titer.
Lyme: no equine vaccine available in the US. One single study using canine vaccine which demonstrates short lived immune response. No challenge studies showing actual immunity conferred. Disease is very rarely fatal, overall very treatable. Not directly transmittable to people.
Your take: vaccinate blindly with any canine vaccine, even one with zero published study in equines. Don’t bother titering. FDA requirements are too onerous to ever see an equine vaccine.
We’re clearly very far apart on this issue, but you should really examine your own bias, because how you treat the vaccines that are actually approved with considerable study in equines and cause ugly deaths is very different than how you treat the vaccine that has zero approval in equines, and one single published study, for a disease that very rarely leads to death.
Btw, this?
Yes, exactly so. Which is why titering doesn’t tell the whole story. But you seem to think we should accept that for a disease like rabies…100% fatal and transmissible to PEOPLE.
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Not a comment about vaccines but, I tested my 20 yr old gelding last week who has lost topline and has been walking slowly and showing a bit of extra effort getting up after lying down. He’s out with a herd 24/7 in a pasture in the NE. Plenty of ticks to go around here.
He did have acute Lyme once — a decade ago — and was treated with Doxy successfully. Anyway, so the Multiplex test from last week came back from Cornell showing positive for chronic Lyme… OSPF: 2023 — which is very low in the range (but still positive), the range being 1250 - 26,000.
Apparently treatment recommendations for chronic vs. acute Lyme are now to treat with Minocycline not Doxy, as it’s supposedly more bioavailable. Of course I have plenty of Doxy on hand but No Minocycline. Should I spring for the Mino and not use my Doxy? Should I even treat? Sure the symptoms I mentioned above could be anything but you know when your horse has been seeming … different.
Sigh. I welcome any input re the above.
If you can afford it, go for mino. I have a chronic Lyme horse too. I’d like to say I have a good eye for noticing these things. Problem is he was more stoic than he let on.
Thanks, what’s been your treatment protocol (duration, dosage) and do you buy it compounded? Powder? Ty
I agree with you concerning the vaccinations. I don’t booster any of my spring shots unless I am required to for a horse show entry. I also hold off on the spring shots and do the ones for mosquitoes in may or June…in New England I don’t have to worry about mosquitos after September so no need to booster.
I have never had the Lyme shots done on my horses and have only had to treat them for the other tick borne diseases like erlichia. Most of our horses here test positive for Lyme but are not symptomatic.
I lived on MV as a kid and we were always covered in ticks. I test positive for having had Lyme but again have only sought treatment when I get the high fever one from a recent tick bite.
That being said, horses, just like people can have a debilitating disease from ticks.
No vaccine is 100%, and any potential or known exposure to a rabid animal should almost always warrant a booster. There are many reasons why a given individual doesn’t mount an appropriate immune response to a vaccine, including the use of NSAIDs at or right before the time of vaccinating to mitigate major enough vaccine reactions.
Some vaccines provide a higher % of immunity than others. PHF is one that has low immunity, partly because of the number of strains. WNV and EEE aren’t 100% either, but every year, of the horses who die from them, most are either completely unvaccinated, or are young (like 1-2-3) without mature immune systems, or haven’t been vaccinated in several years. Very few are recently and properly vaccinated adults.
“there remains minimal published data on the correlation between RVNA levels and protection of horses against rabies,”
Titers are only ONE measure of protection. They are antibody levels, the humoral level, but they don’t tell you anything about the rest of the immune system which includes the cell-mediated
You even said it yourself:
There are assumptions made on immunity when using titers. Some have shown to be more reliable than others. But until there are rabies challenge tests, with horses, proving that .5IUmL level also confers immunity, it’s not ok to assume it means immunity.
That said, if a horse is reactive enough to the vaccine titers are the only way to go, and at least the .5IU/mL is a starting point for determining if his life needs to be risked in order to vaccinate him again.
that’s kind of the whole point of the vaccination, to stress the immune system into creating as protective a response as we can hope for
I see at least 2 options:
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test in a month and see if his level is rising. If so, treat, and yes I’d to mino
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At 20, test for PPID, assume some arthritis and try a round of Adequan
Just know that some years there’s a longer Summer ,and a surge of mosquitoes. I remember just a few years ago, there were suddenly quite a lot (relatively speaking) of horses in the general NE area popping up with WNV, due to a warm Fall. So while it might not be common, keep an eye on things. That said, if you’re not vaccinating until June anyway, protection is likely high enough in Sept and even Oct, to not worry
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yes that was my point
My horse tested positive on the Cornell test: 4K OspA; 10K Osp F. What is the best way and form of minocycline to administer? From a previous thread one person had success feeding capsules. At this time I am syringing doxy into him as he will not eat it in his feed. I can find mino in powder, capsules, and paste.
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Mine eats mino capsules without any issues. She gets 3/4lb TC Balancer, 1c beet pulp shreds, copper/zinc/salt, soaked for a few minutes. I toss the capsules on top, and she just eats it. I do sweep bedding back so anything she drops I can see, and she can eat back up. Occasionally I find a capsule that dropped, and I add it to a tiny handful of alfalfa pellets and she eats it up. Sometimes I toss 1/2c of alf pellets on top of the capsules in the bucket, and I haven’t decided yet if that means she snarfs up a dropped capsule or 2 along with any dropped food or not, it’s too random when I find one. The caps aren’t large.
