Lyme disease

Why am I up at 4 in the freakin' morning? That would be becuase of that gosh dang blankety blank rash on my arm.

Remember when I sad that it was similar to a poison oak reaction? I said that because very few other contact dermatitis reactions (and trust me I've had a few....) are uniquely as infuriatingly itchy followed by chemical like pain and burning. Not to mention it's going through the typical cycle. A few bumps here and there the first 2 days that are itchy and annyoing.....patches of intensely painful itching rash (at day 3)....oozing and crusting (at day 4)....and finally at day 5, the panic that this is just going to continue to get worse, even though there is like NO WAY possible for it to hurt/itch/burn more but if it does life will end becaise I'm already NOT sleeping because of it, am a complete grouch, and am on just-this-side of horrible self mutilation.

It's usually on day 5 that I go in and get a shot of whatever they want to give me.

Of course, that's usually because it's on my face or my face is swelling lke a chipmunk.

This is on my arms. I can be a big girl. I can deal. I can stay up until midnight slathering all sorts of creams (given to me by doctors for previous dermatitis reactions - I'm convinced they are all placebos) and repeat at 4am.

As I lay there last night, I decided that of course this is poison oak, I just needed to figure out how I got it. It's not something that grows where I live, work or play - and I hadn't been to an area either hiking or riding that might have exposed me. It's completely limited to my forearm and back of one finger - which is really really really odd since usually I'm sensitive enough that it would be all OVER if it was on my sleeping bag, pad, camp pillow, car etc..........

In the daylight I couldn't make out a pattern to the rash on my arms but laying there in the dark not scratching (much) I had a revelation!!!!!! The odd stripes and criss crosses were from something being wrapped around my arm. Like a leadrope.

It's worse on the right than the left because Farley runs on my right side. It's on the back of my left hand because if I carry the rope while running instead of having it passively on my arm, I carry it in my left hand with the rope across my body.

I had gone running Wednesday afternoon with Farley which make it exactly 24 hours before the bumps started to appear (which is when they will appear if I'm going to have a reaction like this - bumps etc. that show up in the more typcal 3-5 days will be much milder).

I use a cotton leadrope that I make myself. It's dropped, dragged, thrown over hitching posts and rarely carried, tied, or held. The lead rope is on that horse just long enough for me to throw the clip on bridle with clip on reins and then it remains dangling from the hitching post or on the ground until I'm done.

Except when Farley and I go for a run. Which hasn't happened FOREVER. Until Wednesday. When I went out for a 3 minute, 30 mile, hot sweaty run with that rope in constant, rubbing contact with my arms because if I can I drape the rope across my arms etc so I don't have to carry it.

I make my own leadropes for a couple of reasons. a. I can't find a good cotton leadrope with the hardware I want that isnt too soft without paying a ton of money. You've already seen how I use my leadrope. Why would I pay $50+ for something that I'm going to use as a tool? b. Farley used to pull back and even mediocre leadropes get pricey (and I haven't had one of mine break.....). c. I can throw it away without guilt when it's used up but non worn out. I counting getting poison oak on it as "used up".

So, it's off to the hardware store (again...but more on that story in a future post) to pick up new rope, and while I'm at it, I'll probably make 2 leapropes - one for my routine stuff and another one just for running..

OK. Since placating my arms with attention, placebo creams, and the like, I think I can get through one of my convention seminar posts without too much distraction.

Lyme disease - this was a very cool seminar because it was co-presented by a medical doctor and a veterinarian. It's a format being used more and more in the veterinary schools (called a "one health" approach) and in fact, my classes this afternoon will consist of small group meetings with my class and 3rd year medical students and working on some cases with a one health relevance.

Normally this isn't a seminar I would have made time for, but since I'm in the middle of my infectious disease block, and I was having SCAVMA paying my hotel and convention fees, I figured I could go and call it studying......

I'm not going to go into the disease and pathogenesis much here - that information is readily available from a bunch of different places. Somethings to consider/keep in mind for the "typical" lyme case:

Horses:

• Typical clinical signs usually include shifting lameness and uveitis. However can be a variable presentation.
• Poor recoveries during competition.
• May or may not see ticks - the nymph stages can be very tiny! This goes for your dogs, cats and yourself. Typically you will see ticks on them at some point if you have ticks in the area.....but keep in mind that you cannot say with confidence that your animals are not being bitten if you are in a tick area and they aren't on prevention.
• Lyme is everywhere. There are areas of lower risk, but lyme is everywhere.

The veterinarian that presented lives in an endemic area and has been treating Lyme for a long time. I think many of the details of the presentation were based on her personal experience - she mentioned starting protocols on her own horses before trying them on clients horses. I have a family member with chronic lyme so it was interesting to see what was recommended for treatment. I don't intend on giving you a complete treatment picture, BUT I wanted to share with you the kinds of things involved in treating lyme n horses.

• treat with tetracycline - IV is best and you are looking at 30 days of treatment. An IV catheter is placed in the horses neck and the protocol is administered by the owner with the vet checking in about 1/2 way through the treatment. The protocol wasn't horribly expensive - somewhere in the neighborhood of $500-800, but Lyme isn't one of those diseases where it's a one shot deal and now it's cured. I must admit that I sat there wondering whether I had the fortitude to treat and deal with a horse that was chronically showing symptoms of Lyme. The good news is that a lyme horse can be treated and be useful. The bad news is that it isn't as simple as 1. vet comes 2. vet cures.
• Mitroionazole added to the protocol is very good.....but very expensive right now. A figure in the $1500 range was thrown out. This drug belongs to a class of antibiotics that can target all sorts of atypicals, protozoan parasites, etc. and she's currently trying another drug in the same class to see if there's an effect at a lessened cost.
• Oral DMSO at 2 and 4 weeks (stomach tube) which corresponds to the middle and end of IV treatment. This vet felt like administering DMSO helped get the medications into joints and tissues that weren't highly vascularized. She did mention that it's a dehydrating agent that can be caustic (which is why it had to be given via stomach tube) which made me wonder whether that is why it's being used in Furacin/sweat wraps - it's pulling water out of the skin in a dehydrating effect. For those readers that read Which would explain why it makes the leg look better - however I'm still on the fence whether it's a reaction that is physiological helpful or a placebo effect that helps us horse owners stick our heads in the sand (ie - by dehydrating the skin and making the injury look better, are we actually making it better?)

Don't treat asymptomatic horses - their immune system is handling their disease. An important point in vetmed (and other industries) - tests are information and you should know what you are going to do with the test results (positive or negative) BEFORE you run the test. Testing shouldn't be a shot-gun approach, let's see what comes up, thing - testing should be done for a REASON. Testing has a cost and it isn't just a monetary one. My experience in the food industry has made me very aware of this concept. There are protocols of what and when to test, and what happens when those results are positive or negative. Veterinary science is no different. Why is the test being done and what are you going to do with a negative or positive result? One thing that frusterates me in a teaching hospital (especially in the small animal side) is the lack of ability to make a decision without what is called "the minimum database". Which consists of blood work, chemistry (+/- urinalysis), throacic radiographs, abdominal ultrasound. We are told as students that in reality we will make diagnosis's without this "minimum database" in the real world, and certainly in food animal medicine! Yes, it provides a lot of information, but to what point? Are we using a shotgun when a .22 would suffice? Are we treating numbers or the animal? Testing the entire herd for Lyme doesn't make sense. What are you going to do with a positive result in a asymptomatic animal? Treat it until it's asymptomatic (again)? That makes no sense whatsoever. Know why you are testing and what you are going to do with the results before you test.

A side note here - this entire post was DONE and then my blogging software crashed. I am NOT happy, so if I seem a bit grumpy right now, I AM. Rewrites are always better right? You are more decisive, communicate clearer......sure.

The point about testing and treating was a sticky point for the audience. In the horse world, you send blood off to Cornell for their "multiplex test" and get a result back. You treat, and retreat if necessary. In the human world, inconclusive results are the norm, you can start treatment for Lyme and be negative, and then halfway through treatment be positive. The guidelines of the I-forgot-the-name-but-they-are-important organization that prints such guidelines says that while treatment for Lyme (humans) is often incomplete, reteatment is not indicated. And that's how it is folks - There are many differences between vetmed and human med, but I find that often the tests and technologies and protocols that I get to use are in many ways ahead of human med. The validation and testing that is required to bring a animal medication/vaccine/test to market is way less than on the human side and as a result the technology in many ways is further along.

The vet suggested vaccinating horses with Lyme using the dog vaccine. Specifically the Merial OSP A vaccine recommended. This is off label use, the vaccine is NOT approved for horses, and as such it is up to the individual owner to decide what they want to do!!!! What was interesting is that the vaccine was suggested as both a prevantative AND as an adjuvant (no pun intended....) to therapy. The first use I'm familiar with, but typically once an animal is sick, vaccination isn't going to help....However after understanding the pathogenesis of Lyme better, I can see her point. Without going into the excrutiating details of immunology (and after having 8 weeks of it, I am NOT going to subject you to that) here's the basics. The lyme organism "expresses" a certain thing in the tick - let's call it "OSP A". Once it enters the animal the lyme changes expression to "OSP C". Thus acute infections will be characterized by high levels of OSP A, while more chronic infections will have high levels of OSP C. Vaccinating against OSP A will cause an enhanced immune response against OSP A......hopefully clearing it so that it never gets to turn into OSP C! Thus vaccinating against OSP A will prevent new infection and more spirochetes entering the body system, just leaving the OSP C from previous infections for the animal and the vet to deal with. Because effectiveness of treatment is measured as OSP C levels, which have not been messed with by the vaccine, you can still use the multiplex test to monitor treatment. Not all horses respond to the vaccine (response can be measured by looking at the amount of OSP A titer levels before and after vaccination) but a significant proportion due. In this vet's experience, she's never had an adverse reaction to the vaccine. Protocol recommended was a 2 dose series - given a couple of weeks apart, followed by re-vaccination every 6 months.

Like most conditions, prevention is the best medicine. Keep the ticks off. Tick repellant can be added to vasaline and smeared on susceptible areas of the horse like around the tail, muzzle etc. Another control strategy suggested was tick tubes. A property is seeded with small plastic tubes stuffed with fluffy stuff that's been impregnated with a tick killer. The small mouse like rodents collect this fluffy stuff and use it for bedding/nesting, where it kills their ticks.....breaking the life cycle of lyme! Very cool idea. Apparently this works on a smaller property (10 acres or so) but not on the larger ones.

I came into the seminar late so missed much of the human medicine portion of the seminar, but one concept that I remember is that if you are going to treat human lyme disease after a tick bite, before the onset of symptoms, do it right or don't do it at all. Right = antibiotics for 3 weeks. Anything less and don't bother.

One last thought - remember that your older horses are more susceptible to Lyme. Many horses older than 20 years of age have some sort of Cushing's like syndrome that results in increased circulating corticosteroid levels in their body - which is an immune suppressant. Although many horses won't show symptoms until 20+, immune compromise could be present years before that. I would pay close attention to horses in their late teens in my herd and assume that they are more susceptible to all sorts of diseases, not just lyme. It's a paradox - titers may be high from years of vaccination, however at the same time they are more suceptible to disease.

I know I have readers that have Lyme disease, and I would be curious to hear your thoughts on this information. Has anyone had a Lyme horse? It isn't terribly common in this area, but I'm super careful about keeping ticks off me based on a family member who has Lyme.

 

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