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  Discussion on Exposure to Symtoms...How Long?
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New Member:
lisap

Posted on Tuesday, Mar 1, 2011 - 11:00 pm:

I have an 11ish draft cross mare that has been having subtle shifting lameness issues for about the past 4 months. In the past 2 years or so, I have noted that she has had difficulty getting up. She will sit up like a dog, then spin around about 180 degrees before lurching to her feet. But in the last 8 months or so has stopped laying down altogether. She won't lay down to roll or to sleep. She is now sleep deprived and falling asleep on her feet and has fetlock sores and knee rubs. About 1.5 years ago she was diagnosed with arthritis in the hocks. Injections helped the first time, but not the second. She was then diagnosed with arthritis in the neck between C1 and C2 last week and injected. So far no change and still not laying down. She has also been on Previcox for a couple months which initially seemed to help a little with the lameness, but not laying down. She has no definite neurological symptoms. Today vet calls and said blood test for EPM was positive.

This mare came from Wisconsin at about 9 months old and has lived in SW New Mexico since then. I have never seen an opossum here. I'm not sure we even have them here. My hay has been local grown or shipped from Arizona. So not sure she could have been exposed here. She could have been exposed in Wisconsin some 10 years ago. Could it take that long for symptoms to start to show? Or can I rule out EPM since she likely has not been near a possum in 10 years? I don't want to do the spinal tap test or start treatment if there is little chance that she actually has EPM.
Moderator:
DrO

Posted on Wednesday, Mar 2, 2011 - 8:09 am:

Hello Lisa,
Weakness not attributable to lameness or muscle disease is a specific neurological symptom but usually accompanied by ataxia. For more on the diagnosis see HorseAdvice.com » Diseases of Horses » Nervous System » Incoordination, Weakness, Spasticity, Tremors » Diagnosing Incoordination, Ataxia and Weakness for more.

While how long it may take to develop EPM is not known, research currently suggests that EPM develops within months of exposure not years. However Sarcocystis (comes from exposure to opossum feces) is not the only organism to cause EPM. The closely related genera of Neospora which is transmitted by dogs is possible. Lately we have had some postings suggesting that Parelaphostrongylus tenuis (white tail deer definitive host) may also figure into neurological disease caused by aberrant parasite migration.
DrO
New Member:
lisap

Posted on Tuesday, Mar 8, 2011 - 11:35 pm:

Thanks for the reply. She doesn't seem to have any ataxia symptoms. The vet did general neurological tests and she didn't have any symptoms. So it seems it is more likely pain and or muscle weakness. I did see evidence of her lying down today. There was a a "smushed" spot in the sand, but based on the disturbed ground around it, she had to struggle around to get up. I could see the marks where she spun around on her hocks, even pulled some tail hair out, to get her feet under her.

I read the article about weakness without ataxia and I noticed one cause could be abberant parasite migration. This mare was full of worms when she came to me and had chronic colic for months during her first year with me. She has been wormed regularly since, but could this past worm infestation be causing these symptoms now? I tried a Google search, but didn't turn up much.
Moderator:
DrO

Posted on Wednesday, Mar 9, 2011 - 8:30 pm:

There is not enough information to make such a judgement, Lisa, but it seems unlikely. From your last description and your first post pain may be what keeps her from lying down.
DrO
Member:
lisap

Posted on Sunday, Mar 13, 2011 - 5:08 pm:

Guess I am just looking for any possibility at this point. After hock injections, neck injections, and daily pain killers (previcox), I am seeing little to no improvement. I know she is rarely lying down, and I am not sure if the evidence I saw a few days ago was from her laying down or possibly finally falling completely down during one of her sleep crashing episodes. She is out there right now swaying and buckling, asleep on her feet. I am so concerned that she is going to go down and not be able to get back up someday while I am at work. I talked to my vet about looking at her back, hip and stifles, and they said it is almost impossible to get an x-ray of back and hips, and said stifles were difficult. It is so frustrating, I just want her be comfortable.
Moderator:
DrO

Posted on Monday, Mar 14, 2011 - 5:00 pm:

Lisa could you be looking at mental depression do to CNS disease as opposed to just tiredness?
DrO
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