Thursday, October 4, 2012

Lyme Disease Treatment in Horses

First, a disclaimer - I am not a vet and have no veterinary training - I'm just a horse owner and try to be as informed as I can.  Nothing I write here should be taken as diagnosis or treatment advice for any horse - my experience with Lyme is limited.

Lyme is a complex organism, with a complex life cycle.  It's present in the Americas (one major phenotype group only) and also in Europe and Asia (three major phenotype groups, although usually the two that aren't present in the Americas).  It's been recognized as a disease only since the mid-1970s, and research is ongoing.

Here's a  good semi-technical description of the organism and infectious process in humans - good photos, maps and interesting technical information.  I don't know if the testing protocol in humans described in the article is up to date or not, but in horses (and I believe also in dogs) there is a new ELIZA test from Cornell that is more definitive and identifies antigens A, C and F, the variable levels of which help identify what stage of the disease process the horse is in.

The Lyme disease organism is designed to succeed - it has several mechanisms that help it evade the immune system.  Due to its physical structure, it is less identifiable to the immune system that other bacteria - the structures that would typically present as "foreign" to the immune system are not exposed on the surface.  Lyme also actively surpresses the host's immune system - this may partly explain why Pie was vulnerable to EPM in the first place and then had sequential infections with different phenotypes.  Lyme also can colonize poorly vascularized tissues - like the synovial fluid in joints - which makes it less visible to the immune system and harder to treat.  Lyme can even encyst - become dormant and invisible for a period of time. One of the challenges in treating Lyme is that encysting can even occur as a result of treatment with antibiotics - this is one reason for the persistance of Lyme and development of chronic Lyme.

One of the challenges in detecting early Lyme infections in horses (and dogs as well) is that the typical human "bullseye rash" is not present - it apparently is also not always present or is missed in humans.  Pie had many of the typical Lyme symptoms back in the summer and fall of 2011, but none of us - me, my vets, or the university equine veterinary clinic, thought to test for Lyme.  Pie had many of the symptoms - fever, swollen glands, depression, evidence of inflammatory processes - a case of laminitis that did not proceed to rotation, and a few odd skin lessions -more about that below, abdominal discomfort that the vets were able to determine was due to swollen abdominal lymph nodes, signs of head pain as well as extreme muscle soreness - he had an episode that resembled tying up but wasn't - and extreme sensitivity to touch.  Pie also developed extreme visual reactivity at that time, and went from being calm and quiet on the trail to extremely spooky and reactive - I had a very serious fall off him in June of 2011.  The good news (probably not from his point of view, since any symptoms are too many) is his symptoms today are limited to visual reactivity, grumpiness, and some muscle soreness.  He shows no sign of arthritis or lameness of any type, and is willing and able to work and move out under saddle, although he does fatigue more quickly (probably the muscle soreness) and he looks and feels somewhat "tight".

 Here's a photo of annular skin lesion in a human caused by the Lyme organism - Pie had several of these - they were ringlike, an inch or so in diameter, had a raised, scaly border and a depressed center.  They were on his body, and although I noted them no one had a good explanation for why they were there.  They disappeared over the fall of 2011 as the severe symptoms abated.  He still has two residual patches of scaly, thickened skin in front of the points of each of his hips just where the hair whorls are - I don't know whether they're associated with his chronic Lyme, but I'm suspicious, as they weren't there before he was sick.

Lyme has been shown to be treatable with doxyclycline (a member of the tetracycline class of drugs).  These drugs interfere with the reproduction of the Lyme organism, so are most effective when the organism is reproducing.  The objective in treatment is to, over time, affect as much of the bacterial population as possible when it is vulnerable.  Many bacteria reproduce rapidly - every 20 minutes or so - whereas Lyme has a much longer reproductive period - 7 to 12 hours or even longer.  Therefore short-term antibiotic theraphy - as would be used for a rapidly-reproducing organism like strep - is ineffective in treating Lyme.

The expectations in treating Pie are to knock back the organisms to the extent possible.  He hasn't had Lyme for as long as many chronic horses, and his titer levels for chronic Lyme are not at the high end of the range. It is still probable that not all the organisms will be eliminated, due to their ability to hide, but we're expecting significant improvement in symptoms.  Apparently follow-on flare ups are possible, but these apparently respond well to another course of antibiotics (this good response to repeated treatment is also true for dogs, according to Cornell, but apparently less so for humans).

My vet is using a revised treatment protocol.  Many horses have been treated with doxyclycline pills split into two daily treatments - for the average 1,000 to 1,200 pound horse (Pie is in this range) the treatment has been 50-60 doxy pills twice a day.  The revised protocol goes with the total dose - 100-120 pills a day - only once a day.  This apparently has something to do with the way the Lyme bacteria operates in the animal - it's apparently more vulnerable to treatment in the late afternoon and early evening, and less vulnerable in the morning.  I believe this has something to do with its reproductive behavior.  I'm trying to get more information on the science behind this - it's apparently based on ongoing research of what's most effective in treatment - I don't know whether in humans or horses.  I haven't been able to find anything yet published about this, and it's quite possible I'm not properly describing the thinking.  This protocol allows the peak dose of doxy to be higher, which also may improve the effectiveness of the treatment, while giving the horse a recovery period each day to reduce side effects.

The most significant side effect of doxy in horses is loose manure. To manage this, the other part of the protocol we're using is to very slowly increase the dose, starting with only 10 pills and increasing by 10 per day, and watching carefully for any loose manure.  The goal is to build to at least the 100-120 pills per day level, and possibly somewhat higher if Pie tolerates it well, and hold that level for 30 days once reached.  Some horses have to back off to the 80 pill per day level, but can still get effective treatment - this was true of one horse at my barn - and some horses can tolerate much higher levels of doxy. The objective is to customize the treatment to the horse and get the highest loading dose possible that doesn't cause loose manure.

The nice thing about the once a day treatment is that it's easier to do - I'll do it myself to be sure every little pill is consumed and not dropped - most horses just eat them without a problem, although I may use a feed bag to make things simpler.  The doxy will be fed as whole (tiny) pills together with a small grain meal, to improve gastric comfort, and hay will also be available before and after the treatment. If Pie has any dislike of the pills (the other horse at our barn ate them freely), a bit of cocosoya oil will solve the problem.  Once a day treatment also means I can continue to use supplements that contain calcium or magnesium that would otherwise interfere with the absorption of the doxy, if I give them in the mornings.  Pie will also get a good dose of probiotics each morning throughout his treatment and for a period thereafter to help maintain healthy gut flora.

I'm hoping the treatment will help Pie out, and also that perhaps I'll get a break - I hope a very long one - from learning about new equine diseases . . .

40 comments:

  1. Luckily I seem to have caught my own Lyme's very early on. There was a vaccine on the market for humans, but I don't think it was deemed too effective. There was also talk that the body could develop an immunity after and attack.

    When the disease does get into the joints, that's when it does its best hiding, as you note. Early on it was not part of a regular workup when people had symptoms--unless the bullseye rash showed up. Who knows how many cases of rheumatoid arthritis were actually Lyme infections?

    I guess too, some of the more modern testing techniques (ELISA) as you note are far more accurate in detecting an infection than the old western blot tests. Good thing too, as it enables a much more accurate treatment.

    Very interesting detective story going on here with Pie. Everything you say makes so much sense in hindsight. Now, what you need is a good recovery. Well done, Ms. Sherlock! *S*

    Wishing Pie very, very well!

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  2. Kate--I treated Henry with doxy for a couple of months--he had an incisional infection following colic surgery. As you described, he ate the tiny pills, no trouble--I just put them in his regular equine senior feed. I worried about side effects--but he never had any. The infection (eventually and slowly) cleared up. I hope Pie tolerates the drug equally well. And I hope you are done investigating weird equine diseases--not that it isn't interesting, but you could use some nice uneventful horse time(!)

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  3. My friend teasingly referred to me as an "internet vet" when my dog Sweetpea got her rather diffuse diagnosis of Cushing's disease...

    It certainly helps to be armed with info in order to make informed decisions as our companions advocate. Thanks for sharing your research.

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  4. I really hope you get a break after this. You and your horses really do deserve one after all you have been through.
    Very informative post and thankfully it is not something we see around these parts. And hoping Pie has a speedy recovery!!

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  5. I treated my horse 2x for Lyme with the 30 days of Doxy.
    Third and final time was with the IV oxytet. That is what seemed to finally kick it out. He has tested positive that 3rd time to chronic and acute Lyme using the at the new Cornell Multiplex test. I had thought that the current preferred treatment was the IV oxytet. Did your vet mention that?

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    1. Angela - IV treatment does work, but as I understand it it is often done at a veterinary hospital and may require the insertion of a catheter - was yours done that way? - that option is one I would prefer to avoid, and I believe the treatment presents certain risks to the horse that don't exist with the oral doxy treatment. Very effective treatment though.

      The once a day higher dose doxy protocol we're using is designed to be more effective than the older twice a day split dose protocol - I don't know yet if that will prove to be the case but time will tell. Also, my horse's current symptoms aren't that severe, and his titer level for chronic Lyme is not that high above the cut off level, so we're hoping that this treatment will improve things. I understand that relapses are possible.

      It's good to know that IV treatment will do the trick even for chronic Lyme, as well as acute infection, so that we can keep that in reserve.

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    2. When my horse did the IV - my vet came out to the barn and put a port in - so I did the actual treatment/flushing 2x a day. He wore a sleezee to keep the port clean and safe. He was (I have since rehomed him)a young, very playful gelding so had to be separated from his favorite playmates. He did manage to keep it in for almost 3 weeks before one of his buddies ripped off his sleezee and I had to get it reinserted. There is also a study going on at New Bolton and there is apparently an even newer antibiotic that they were recommending.
      It sounds like you have a good plan and as you mentioned there are also other treatment options if the doxy doesn't kick it out.
      Good luck!

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    3. Angela - glad your horse is doing well now. Do you know what New Bolton is recommending, and whether it's for IV or oral? I looked on their web site and wasn't able to find anything about it.

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  6. Wow, this is interesting stuff. I never would have thought of Lyme disease - it's just not that common here. I'm so glad you've got a diagnosis and are on the right track to get Red better. So happy about that! Poor guy (and you) have been through the ringer!

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  7. It can be such a nightmare to find out what is wrong with a horse! Cassie has not been well for months, and we still don't know what is wrong with her. She is lethargic, still full of hives and intermittently lame. Sigh... I'm glad you found out what is wrong with Pie, and hopefully he'll soon be his old self. I had no idea Lyme's disease could have such a devastating effect on horses!

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  8. Kate - Very interesting information, thanks! I would also be curious about the New Bolton recommendations. Once Lyme has entered your barn, your life, you will find this unpleasant visitor returning over and over. I'm glad that Pie is eating the Doxy so easily. That was such a big ordeal for me when I had to treat Siete. She was so finicky that she just refused to even look at her bucket if I put it in there. I'm very interested to see if the 100 pills once a day helps Pie get well faster. Once they are on the Doxy, the symptoms disappear and they feel better almost right away.

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  9. Kate - thank you for writing about these "journeys" you're having with your horses. I hope the treatment works as expected and you can finally get Pie feeling better.

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  10. My Dutch Warmblood responded very well to the Doxy when he contracted Lyme two years ago. However, since then we have noticed a number of changes. First, he has become an extremely hard keeper. Under the supervision of our vet, he is getting 10lb grain a day, plus beet pulp, plus probiotics, plus both Timothy and alfalfa and being in pasture 24/7. We are lucky to keep him at 1100-1200 pounds when before Lyme he was steady at 1300 pounds with no where near that much feed. He has also begun to demonstrate "bad" behavior -- ranging from kicking fences to charging people -- about every 6-8 weeks, which is the reproductive life cycle of the Lyme bugs. His titers are clean, but there is some thought that enough are still in him to make him very uncomfortable when they are "breeding." After speaking with vets and some feed/supplement people, we are starting him on a hind gut supplement and hoping this addresses that behavior. I would be interested in hearing if others have had this situation and if you see anything like this as your kid recovers!

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    1. Fran - I'm new to this - Lyme that is. My understanding from my vet is that even with the higher dose/once a day doxy treatment protocol that we're following, that some of the Lyme organisms may survive - they're tricky buggers and hide out very effectively. If some do survive, we may have relapses that need repeated treatment. And, of course, the possibility of new infection is always there, at least in the seasons when ticks are active.

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    2. Oh, and one other thing - you might want to pose this question over on the Yahoo EPM group, which is currently also taking posts on Lyme.

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  11. Thanks for the lead! I'm going to ask the vet for another titer, especially after this last violent behavior. But in the 18 months since the first treatment, he's always come out "clean." I've also sent an e-mail to a vet I know at New Bolton to see what research and information they may have. I'll pass along anything I hear.

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  12. Hi Kate,

    I would like to hear how your treatment of Pie went with this protocol of once a day in a higher dose (doxy). My horse Caspio was treated for chronic Lyme last year with 10 weeks of doxy (twice a day), made huge improvement despite the very long-term infection (I had rescued him in 2011 from neglect and starvation and it took me a year to get to the bottom of it). He is just becoming symptomatic again (but was also bitten by ticks again....we are in New England!) and I am considering my options. I find your mention of GI tract issues interesting because Caspio gets diarrhea when he becomes symptomatic (which, in his case is mostly low energy, atypical for him, joint pain, muscle stiffness, and spookiness),something most vets see a unrelated, but I am convinced it is related. It even disappeared for the first time under doxy treatment when supposedly he was going to have looser manure.

    Please let us know how your treatment went.

    Christian

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    1. Christian - Pie's treatment went very well. He didn't have any adverse effects from the medication, and is now completely symptom-free, ridden almost every day and looking great. The only residual effect may be some eyesight issues, but those may also be due to a large cyst he has in his left eye - the vet is coming out next week to evaluate. I'm also having him retested for Lyme antibody levels in July - 6 months out from his treatment - to see if the levels are down. I'll probably routinely test all my horses in the summer - we're plagued with lots of ticks here.

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  13. Kate, that is so good to hear. Are you located in New England also? I'm asking in part because I am looking for a vet who is competent with Lyme. It sounds like yours is both solid and has some experimental edge to them. Mine is suggesting to use mino-cycline (oral) rather than doxy, but I'm not finding so much information on that. He also advocates the dog lyme vaccine to stimulate the immune system in chronic lyme horses, and I have heard hardly anything positive about that vaccine anywhere...so I'm doing a lot of research before committing to anything too experimental.
    Have you considered doing a homeopathic follow-up? Many people swear by Ledum 1M.
    Christian

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    1. Christian - I'm in northern Illinois. Try calling Cornell for vet recommendations - they're the ones with the new blood test and will know who in NE is up to date.

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  14. My horse was just diagnosed. I bought her for breeding because she was lame... after trying three times to get her breed I started doing blood work. She tested low positive for lyme. I was told 3-5 days IV then the rest of the 30 days pills. She was never treated. I believe she has had issues for many years. Im surprised I don't see more issues with her. She does have weight issues. Looking for supplements that would help flush out the bugs while on the antibiotics and to help with the inflammation in the future. THANKS! Jen

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    1. I used pro-biotics during the antibiotic treatments - my horse had no adverse reactions. I also use vitamin E with all my horses, for nervous system and immune support - they all three have had EPM as well as Lyme in Pie's case.

      Good luck!

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  15. Kate, the ring like lesions you spoke of, did they appear for a few weeks then seem to leave for months at a time only to reappear? My gelding has had these ring like lesions that the vet couldn't figure out that would come and go. Now, many months later he is sore and the vet is suggesting Lyme disease testing.....not knowing about these past lesions. Your post is the first I've seen mentioning them. My horse had sometimes 5 usually barrel and neck areas, but look like that picture in that they are ring shaped, crusty and hair falls out. Thanks, Michele

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    1. Michele - In Pie's case the skin "crusty" things were pretty persistent, although he didn't have Lyme for that long at the time - he had matching circular crusty patches on both hips, right at the top of the hair parting that runs from the stifle up to the hip. These disappeared as soon as he started treatment with doxycycline for the Lyme, and have never reappeared. I suspect they're analogous to the bullseye rash that human Lyme patients get, although that may not be correct - but Lyme does affect the skin.

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    2. Michele - in reviewing my notes, I see that the circular crusty patches mostly went away when the acute Lyme phase was over, but didn't completely disappear until he was treated.

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    3. I just bought a pony for my grand-daughter and now I'm questioning if she (the pony) could have lyme. She is a very quiet, docile pony (13 hands). She had bad feet--cracks, chips, flares, some laminitis. I trimmed her feet and she seems a little better. She refused to pick up one front foot at all, I figured because the other was two sore to stand on (the other was the worse). I didn't feel any heat in her feet, and don't see any swellings in her joints. She gets down to roll ok, but she moves very slowly. I thought she would make a good children's pony, but now I worry about the added cost if she does have Lyme. How much is treatment, on average? Any comments on whether this sounds like Lyme? I didn't realize the foot problems could be a symptom of lime.

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    4. It could be Lyme - the test from Cornell is relatively inexpensive and the treatment with oral doxycycline is dirt cheap - but footsoreness/laminitis is very common in ponies due to their metabolisms. You have to be very careful in feeding them - limited grass, particularly when the grass is rich, usually no supplemental grain - a mineral/vitamin balancer pellet is sufficient - and hay that is rationed to keep their weight down. It's possible your pony has had episodes of laminitis in the past - even founder, which is laminitis with rotation of the coffin bone - and that this is contributing to the foot soreness. Hoof x-rays would tell you something.

      Good luck - she sounds like a nice pony otherwise.

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    5. I bought a 13-hand 9-yr-old pony mare that had flares/laminitis, but I do my own hooves and felt this was workable, and she was such a sweet pony I bought her. Got her home and she looked "sleepy"--stood with her head down, eyes half closed a lot. Also, she would actually lock her legs to keep them from being picked up--made it tough to do her feet, but I did get them trimmed. But she still moved like she was really sore. And she drank buckets and buckets of water. This made me suspicious; I have a dog with chronic lyme (rescued that way) and he drinks lots of water. Had the pony tested ($70 with farm visit) and she had Lyme. The treatment was going to be $370 for 2 mos oral Doxy, and as the vet said, there was no guarantee that would be it. It was a tough decision, but since I'd only had her a week, I ended up bringing her back to the dealer. It broke my heart but I didn't feel I could put the time and money in that she would require.

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  16. got a new mare last aug and found out in dec she is positive for Lyme. Her symptoms are muscle atrophy, back pain, mild aggression, and super sensitive skin. She just finished 30 days of Doxy with 3 days of Ledum and I don't see much difference. I am torn on doing another month of Doxy or going completely all natural treatment. I've read so many conflicting articles and blogs. One article states boosting the horses immune system is best so the horse can fight this themselves. I am not in a good financial place and going the IV route is not possible for me. Looking for other people that tried the homeopathic route.

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    1. Anon - don't know of anyone who's had success with homeopathy and Lyme. The protocol we used - talk to your vet - was to, instead of a twice a day dose, to do a once a day dose at double strength - it may be that this is more effective. I would see if your vet agrees and try the doxy for another month - once you're at a loading dose. Good luck!

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  17. Kate, we just had one of our horses diagnosed with Lymes, can't afford (and not sure I would want to try the tetracycline) thinking about the doxy, what did you do with the doxy when you were giving it? any probiotics? Is Pie fully recovered? do you need to give him anything on a regular basis any more or is he drug free now? does he have flare ups at all?

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    1. Jeanne - I gave Pie his doxy pills with some grain and he pretty much would gobble them up, even though there were a lot of pills. I did do probes, and he never had any gastrointestinal issues. Pie is fully recovered and has not had any recurrence, although he probably doesn't have immunity against a new infection. I believe the effectiveness of the treatment may depend on how long the horse has been infected - the more chronic the case is the harder it may be to eliminate. I do keep an eye out with all my horses for new symptoms, and the blood test from Cornell isn't that expensive.

      Good luck!

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    2. I meant "probiotics" - darn spell checker . . .

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  18. do you have a phone number or contact info. for cornell?

    Thanks

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    1. Jeanne - here's the main Cornell vet hospital site - I expect they can give you/your vet info about the Lyme test, interpreting the results and recommended treatment.

      http://www.vet.cornell.edu/hospital/services/equine/

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  19. My stallion has Lyme and I have been treating with Minocycline.

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  20. I stumbled upon your blog and was curious to learn about the 1x/day dosing treatment. That didn't seem to upset the digestive tract? I am on year 2, round 2 of treating a chronic Lyme infection in my mare. My vet didn't like the idea of the 1x/day treatment but I am curious and looking for anything to make the treatment more effective.

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    1. Sandy - I'm no vet, but the 1x a day dosing (at double the normal dose) - provided the horse could tolerate it without developing loose manure - was effective for my horse. Theory as I understand it was that the bugs were more active (less protected) in late afternoon, and that the dosing then would be more effective. Also, only dosing with antibiotics once a day gave the horse's system a chance to recover better between doses.

      As I understand it - I have no personal experience with it - some vets are now recommending minocycline for Lyme.

      Best of luck with your treatment!

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    2. Sandy - I should also say that my horse had probably only had Lyme for a relatively short time, and his titer levels weren't as high as they could have been. He responded well to treatment and has not had symptoms since, and follow up titers show that he no longer has an active chronic infection.

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    3. And one more thing - some people have apparently had good results with IV tetracycline.

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