Spinoff thread: Do horses get Lyme disease?

[Lulu]

I'm confused. I've read many articles about Lyme disease in horses, but I've also had some pretty reputable vets recently tell me that the disease doesn't express itself in horses as it does in humans and dogs. They cited research at Cornell and New Bolton, which I can't seem to find online. So what's the story... or is it too soon to know for sure?

Please note: I don't have a dog in this fight. I'm just trying to educate myself.

[LauraKY]

They most certainly do. I'd get myself a new vet! Here's a link to just one of the publications I found. This one from the University of Delaware http://ag.udel.edu/EXTENSION/agnr/pdf/eq-16.pdf

I moved to Kentucky from Maryland 3 years ago. Maryland is a hot bed of lyme. Can't imagine that it hasn't moved south to Virginia.

I just googled horse and lyme disease and came up with a wealth of information.

[JstMyLuck3]

For sure! We've had a good number of cases here in upstate NY.

[twofatponies]

It seems common around here in dogs and horses (and people). Though I do recall that 8 years ago our vets were inclined to say it wasn't something that affected horses. So maybe the knowledge of it has been spreading slowly in parts of the country where it is less common.

[LauraKY]

Found this article on PubMed: http://www.ncbi.nlm.nih.gov/pubmed/15863289?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed _ResultsPanel.Pubmed_RVDocSum&ordinalpos=1

"Antibiotic treatment of experimentally Borrelia burgdorferi-infected ponies.

Chang YF, Ku YW, Chang CF, Chang CD, McDonough SP, Divers T, Pough M, Torres A.

College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. yc42@cornell.edu

The objective of this study is to determine whether doxycycline, ceftiofur or tetracycline could be effectively used to treat equine Lyme disease. Ponies experimentally infected with Borrelia burgdorferi by tick exposure were treated with doxycycline, ceftiofur or tetracycline for 4 weeks (28 days). Doxycyline and ceftiofur treatment were inconsistent in eliminating persistent infection in this experimental model. However, tetracycline treatment seems to eliminate persistent infection. Although serum antibody levels to B. burgdorferi in all ponies declined gradually after antibiotic treatment, three out of four ponies treated with doxycline and two out of four ponies treated with ceftiofur, serum KELA titers were raised again 3 month after treatment was discontinued. Five months after antibiotic treatment, tissues aseptically collected at necropsy from ponies with increased antibody levels after antibiotic treatment also showed culture positive to B. burgdorferi in various post-mortem tissues. However, all four-tetracycline treatment ponies showed a negative antibody level and culture negative from post-mortem tissues. Untreated infected ponies maintained high KELA titers throughout the study and were tissue culture positive."

[SMF11]

Thanks for posting that study LauraKY!

[analise]

Oh yeah, I know two horses that are undergoing treatment (LOTS of antibiotics) for it right now and of at least two more that have had to undergo the treatment. It definitely can show up in horses.

[Lulu]

This is what the vet told me:

1) Lyme titers don't correlate to active disease, i.e. horse can test off the charts and have no symptoms.
2) Researchers at Cornell have been trying to give horses the disease, and cannot recreate Lyme symptoms through exposure.
3) Because the recommended antibiotics are also anti-inflammatories, they are actually treating/curing some other, undiagnosed problem.

Perhaps in the years to come, we'll have a better handle on equine Lyme disease.

[LauraKY]

This is what the vet told me:

1) Lyme titers don't correlate to active disease, i.e. horse can test off the charts and have no symptoms.
2) Researchers at Cornell have been trying to give horses the disease, and cannot recreate Lyme symptoms through exposure.
3) Because the recommended antibiotics are also anti-inflammatories, they are actually treating/curing some other, undiagnosed problem.

Perhaps in the years to come, we'll have a better handle on equine Lyme disease.

That's the same old cr*p we were told when we were first diagnosed with Lyme (human) 7 years ago. Took 10 years and $500,000 of medical tests to get a diagnosis. Yes, titers don't correlate to active disease, at least in humans. You can be very sick and not show a titer because your body is not actively fighting the infection. From my own experience, treat the symptoms! Get thee to a lyme knowledgeable vet. Whatever you do, don't give steroids. The longer you wait to treat, the more likely it will cause serious problems.

[LauraKY]

From a Cornell publication: http://web.vet.cornell.edu/public/research/zweig/Newsletter/2004-05/index.html?/public/research/zweig/Newsletter/2004-05/story3LymeD.htm~Story

"Lyme disease is a bacterial illness caused by the corkscrew-shaped (spirochetal) bacteria Borrelia burgdorferi. It is the most prevalent tick-associated illness in horses, humans, dogs, and cats in the northeastern United States, causing such nonspecific signs as fever, stiffness, muscle pain, and swollen joints. The so-called “deer ticks” or “black-legged ticks” are the most common carriers of the bacteria. The disease is endemic in the northeastern and mid-Atlantic states, Minnesota, Wisconsin, and northern California.

Four to five years ago, equine clinician Thomas Divers, DVM, Dipl ACVIM, and Yung-Fu Chang, DVM, PhD, Dipl ACVM, a professor of population medicine and diagnostic sciences, were swamped with questions about Lyme disease in horses. They began testing the blood of horses to determine how widespread equine exposure to the bacteria was found.

“It became clear that huge numbers of horses in the Northeast had produced antibodies, but no one knew what it meant because no one had done research on Lyme disease in horses before,” says Divers. He points out that in areas where humans are being infected at high rates, more than 50 percent of the horses had been exposed. In Connecticut, more than 70 percent of the horses have been exposed based on seroconversion, that is, the development of antibodies against a microorganism. Despite evidence of high exposure, only a small percentage of horses show obvious symptoms.

Lyme disease is of particular concern to owners and trainers of performance horses, says Divers, because the stiffness and lameness that the disease produces can take a serious toll on performance. Such problems have been observed in Connecticut and eastern New York where many elite show and performance horses are trained.

Since Chang had published a number of papers on Lyme disease in dogs, Divers teamed up with him and pathologist Sean McDonough, DVM, PhD, for a series of studies funded jointly by the Zweig Memorial Fund and the Dr. John Lowe Endowment.

In the first phase, the researchers produced Lyme disease experimentally in ponies to study the response to the infection. They found microscopic evidence of the disease in the layer of skin just underneath the epidermis (dermis), lymph nodes, peripheral nerves, and around blood vessels near the joints. Clinical signs of the disease were not obvious in the experimental ponies, although subtle signs might have gone undetected. Some clinical signs previously attributed to Borrealia, in fact, were caused by infection by another organism, Anaplasma phagocytophila (also known as Ehrlichia equi). They also discovered which antibodies were important in diagnosing Borrealia and the temporal antibody response to infection, both of which have permitted improvements in diagnostic testing and/or interpretation.

“We also found that horses stayed infected for months after the infected ticks were removed, suggesting that the infection is persistent, perhaps lifelong in some horses,” Divers points out.

“All three antibiotics reduced the level of the ponies' antibody response, indicating that the organisms were suppressed somewhat, but only tetracycline completely cleared all four ponies of the infection. - Thomas Divers

In the second phase of the studies, the researchers used an experimental vaccine based on an outer surface protein (OspA) that others had determined was important for immunity in other species. They vaccinated eight ponies on days 1, 20, and 82, which proved protective for an experimental challenge.

“Although the vaccine is very similar to a vaccine available for dogs and to the vaccine for humans—which was taken off the market for possible side effects—we don't know if the dog vaccine would work in horses and we don't know how often the horse needs boosters,” Divers says. “What we do know is that the experimental vaccine provided protection in our experimental model and side effects were not noted. It is unlikely, however, to be effective after an infection has already occurred.”

In the third phase of the study, the researchers analyzed antibiotic treatments. Because the infection did not trigger obvious clinical signs, the success of treatment was based on lab tests to determine if the organism was cleared from the ponies. The researchers infected 16 ponies and then tested three antibiotics: tetracycline administered intravenously, doxycycline administered orally, and ceftiofur administered with an intramuscular injection for three weeks in four ponies each. Four ponies were in a control group. After four months, the ponies were euthanized and evaluated.

“All three antibiotics reduced the level of the ponies' antibody response, indicating that the organisms were suppressed somewhat, but only tetracycline completely cleared all four ponies of the infection. In the other two groups, the antibiotics cleared one of the four ponies but left three still infected,” Divers said. Tetra*cycline was likely the most effective because it was administered intravenously, which permitted very high levels of the antibiotic in the tissues.

“With what we've learned so far about treatment, the reasonable recommendation would be to treat an infected horse with intravenous tetracycline initially, and if long-term treatment were desired, switch to the oral administration of docycycline, which is much more convenient and practical,” Divers concludes.

Drs. Divers and Chang wish to further test the dog vaccine in horses, advance challenge studies following vaccination to determine how often boosters are needed, and change the doses of the various antibiotics to determine if that would make them more effective"

Notice it does not say that horses don't get it, it doesn't say not to treat it, as a matter of fact, they have a short term and long term treatment protocol. They're also developing a vaccine. Now, according to the article, perhaps horses are also infected with Erlichia and the both together will cause the symptoms. Still not a reason to withhold treatment in the face of symptoms! Treat the symptoms!

[Lori T]

Yes, and despite what our officials want us to think, it does exist in Florida..in horses and humans. I had an OTTB catch it a few years ago. We euthanized Pilgrim last year due to complications from it. And my farrier's father nearly died from it, it took nearly 2 years to get it diagnosed. He will never be the same because it took so long to diagnose. I am freaking out because we are having a tick explosion this fall..I feel like I am back in West Virginia.

[wildlifer]

Horses CAN get Lyme disease, but I attended an interesting talk from Dr. Kent Allen, of long experience, who said that Lyme is one of the most over-used diagnoses that there is. It is often diagnosed and treated, then owners will report symptoms going away. But the treating antibiotic contains a NSAID, so what really is happening in many cases is that the TRUE cause of the problems has healed on its own or been covered by the NSAID. So many horses who are diagnosed with Lymes actually have other problems that go undiagnosed or untreated because of the quick jump to Lymes.

[deltawave]

Before everyone collectively tars and feathers the OP's vet, pay attention to what he was quoted as saying. Lyme disease not expressing itself the same way in horses as it does in dogs and humans is not the same as saying "horses don't get Lyme disease".

I'd agree with Dr. Allen though (what a cool guy, I got to spend a day with him not long ago) that it is one of the most over-diagnosed diseases out there, no matter the species. Often self-diagnosed, as well, which is a pity as it makes it that much more difficult to sort out.

I think the issue is not so much that the antibiotic "contains an NSAID" as that doxycycline has (among its many weird properties) some anti-inflammatory effects that can make an animal that's "NQR" transiently better, and when the treatment is stopped, the NQR-ness can again seem to worsen. Again, muddying the waters.

[Lulu]

Here's a better explanation of what I was trying to say:

"We know horses can become infected with this microbe. Both experimental infection and serum antibodies to this organism in endemic areas have been found. The controversy is over what type disease, if any at all, is caused by Borrelia in horses. When horses were experimentally infected, the organism reproduced in the blood, settled in the kidneys, and was excreted out the urine for several weeks, until the horse cleared the organism from their body. The problem is horses that have been experimentally infected showed no signs of illness during the acute and recovery phases. Also many horses with high titers to the organism had no past history of infection."

[Brockstables]

For sure! We've had a good number of cases here in upstate NY.

YES, WE CERTAINLY HAVE!!! :( Picking ticks off no matter what repellant I use, too. Nasty things.

[Androcles]

--------------------------------------------------------------------------------
Quote:
Originally Posted by JstMyLuck3
For sure! We've had a good number of cases here in upstate NY.



YES, WE CERTAINLY HAVE!!! :( Picking ticks off no matter what repellant I use, too. Nasty things.

This kind of an answer seems to indicate a lack of understanding of the question. How does this 'prove' it is Lyme disease or that it exists, and not that it is something else? Or how does having a lot of ticks 'prove' that Lyme disease exists? Maybe it is something else that hasn't been identified yet. As deltawave clarified, the vet said it seems to express itself differently in horses, and how do you explain them not being able to induce it from exposure?
This response is a tautology if there ever was one - my horse has it, therefore it exists.

[LauraKY]

I say the proof is in the pudding. If symptoms resolve, and don't recur with antibiotic treatment, then SOMETHING is causing an infection. Lyme, maybe, something else, maybe. Do you remember 20 years ago when we all thought human ulcers were caused by spicy food and stress. Some doctors still believe that. There are two schools of thought on lyme disease (human). Let's just hope that none of you are ever infected and have to do the research to help heal yourself. I almost lost vision in one eye. Thank god for an extremely good neurological ophthalmologist.

[deltawave]

Ulcers are caused by many things, among them bacteria. Not all ulcers have a bacterial origin. And it's quite possible that not all things that get better after a course of doxycycline (which has anti-inflammatory properties) are bacterial in origin, either. Heck, some things get better with no treatment at all, or in spite of it. :)

[wildlifer]

I think the issue is not so much that the antibiotic "contains an NSAID" as that doxycycline has (among its many weird properties) some anti-inflammatory effects that can make an animal that's "NQR" transiently better, and when the treatment is stopped, the NQR-ness can again seem to worsen.

That's what I meant, I just remembered it NQR, LOL, thanks!