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  Discussion on "sidewinder" synDrOme
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New Member:
lmathews

Posted on Sunday, Apr 20, 2014 - 5:07 pm:

Hello all, I posted a short message under "mare with stroke" and am following up here. Several weeks ago I found my 28 y.o Appdx QH mare standing in an extremely odd way, with her hindquarters canted off to the side. Watching her move was terrifying, as it seemed she would fall over at any moment. She had been perfectly fine when turned out only hours before I arrived (I board her).

The ground was still snowy and icy here then, and the emergency vet thought she may have fallen and injured herself. I thought that her symptoms looked more neuro, though. On a more thorough exam the next day my regular vet agreed, although he could not rule out injury. We tried her on a course of bute, with initial improvement that didn't last. For a short time we thought that her symptoms were improving as the weather warmed, but that did not last either.

My vet has been consulting with a New Bolton neurologist, who taught us both the term "sidewinder synDrOme." The consulting vet wrote what is apparently the only published description of sidewinder, which is in Orsini's Equine Emergencies. Right now it's just a descriptive term for a set of symptoms, and no one knows what causes it -- as the Orsini summary reflects, even on necropsy there have been few consistent findings.

Her EPM titer (vet tested for both S. neurona and Neospora) and Lyme titer were both mild positives, which is pretty typical for our area (midatlantic U.S., Pennsylvania). She had been treated for Lyme before, so we did another course of doxycycline, to no avail. We have recently started a course of pyrimethamine/SMZ, just in case -- although the consulting vet said that there is minimal chance that it will help. We have not done any higher tech diagnostics like imaging; we have been concerned about transporting her.

My horse fits the Orsini description to a "T," for the most part: "crabwalking," hindquarters listing, trying to use her forehand to compensate. But here's a strange twist: she keeps switching the side that she leans toward, and she switches fairly rapidly -- like a few days to one side, then overnight changing to the other. The consulting vet said that she has occasionally seen sidewinder horses switch sides, but over the course of weeks, with a period of straightness in between. We have no idea what it means, but my horse's symptoms are different.

For now my barn manager considers her pasture sound but we don't know whether that will last long enough to give a real chance for the EPM treatment. We are watching her quality of life carefully, and are prepared to let her go if she can't do basic "horse" stuff like graze and enjoy the sunshine. I had hoped to get her to age 30 but I know that 28 is a pretty good run ....

I don't have a specific "question" so much as I welcome discussion! If anyone else has encountered the term "sidewinder" or has a theory about underlying cause, treatment options, etc., I welcome your input.

Lisa
Moderator:
DrO

Posted on Saturday, Apr 26, 2014 - 8:36 am:

Hello Lisa,
I think Sidewinder SynDrOme should not be looked at as a single disease but a constellation of diseases that can effect the nervous system at the same functional location(s). Some of these horses turn out to have EPM, some have Borreliosis, some have unexplained inflammatory lesions and others have had traumatic injury to the spine or pelvis. As you mention all to often no lesions are found so all the causes have not been elucidated. Until the disease causing the lesion is found it is called Sidewinder SynDrOme but I suspect in the no lesions found group there are still several disease entities present which.

I feel like I am just repeating back your post with a slightly different perspective but the important point I think is that it is not a particular disease that causes the synDrOme, lots of different disease can cause it, but it is the location of the lesions that determine the symptoms.
DrO
New Member:
lmathews

Posted on Sunday, Apr 27, 2014 - 9:40 pm:

Thank you, Dr. O; your perspective is helpful. By coincidence there is a short write-up on Sidewinder in this month's Equus Magazine (the "consultants" column). I was struck by the slightly different perspective that the authoring vet had; he seemed to be using the term to include serviceable horses with a crooked-but-stable way of going, which is certainly not the context in which my vet and I have learned the term (as progressive and typically requiring euthanasia). I guess that underscores your point about there being no particular disease process, and variable symptoms.

My mare got considerably worse several days after I posted, spinning and backing involuntarily while turned out. She seemed exhausted from the effort of staying upright. She had been on the EPM meds a few days at that point. With my vet's input we decided not to put her down right then, but to put her on full stall rest again. She immediately leaned up against the stall wall when she went in, and 12 hours later was much improved.

She is still bright, relaxed, eating, etc. so for now the plan is to leave her on stall rest a few more weeks to give the meds a chance to work, on the tiny possibility that they will. Still assessing her quality of life each day.

I do have two questions for you, which this discussion has crystallized, if you have time:

1. Other than the infectious diseases that may cause these symptoms, are any others treatable? I lean against (oh goodness, no Sidewinder pun intended there ...) hauling her to the vet hospital (approx an hour away) for a thorough work-up given her age and how much she's already been through -- but if I thought that there were another treatable option I might lean differently.

2. Does the fact that she switches the direction of her leaning give you any hypothesis about the cause here?

Thank you again.

Lisa
Member:
rtrotter

Posted on Sunday, Apr 27, 2014 - 10:39 pm:

Lisa,

Please check out this website if you think your horse could possibly be dealing with EPM.

https://pathogenes.com/wp/about-us/

She has a testing protocol and specific medications that deal with the different facets of what may be causing your horse's problem including inflammation.

She is very nice to talk to and if your vet is not part of the testing program, she offers a training course for CEU credits.

Rachelle
Moderator:
DrO

Posted on Sunday, May 11, 2014 - 6:44 pm:

Hmmmm...unexplained inflammation may respond to anti-inflammatories either systemically given or injected locally at the site of the lesion. Some traumatic lesions might be repairable through stabilization. Without knowing the nature of the lesion one can only guess at possibilities but I agree that the chance of finding a correctable problem in not good..
DrO
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