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Equine Protozoal Myeloencephalitis (EPM)
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From: reshan@deyr.ultranet.com (C.M.Newell)
Date: Tue, 14 Mar 1995 13:24:22 GMT
In article <3k378u$1vl2@news-s01.ny.us.ibm.net> pallor@ibm.net writes:
>Please post a quickie fact sheet on EPM as soon as you can. A whole lot
>of us are in need of some honest answers about this disease. Some possible
>questions would be:
>How is it transferred?
Ingestion of the organism from fecal contamination of food or water by
infected carnivores--definitive host as yet unknown.
>What are the symptoms (specifically)?
Signs aren't specific, unfortunately. They vary depending on where in ther
nervous system the parasite attacks.They are signs of neurologic damage--lack
of coordination, tripping ,toe dragging, cranial nerve deficits, sometimes
muscle atrophy (secondary to nerve damage)
>Is there an incubation time?
Highly variable. There have been horses apparently carrying the organism for
almost 2 years before signs developed; another horse showed signs before
seroconversion, which usually occurs within a couple of weeks of infection.
>Does a positive blood test indicate infection or just exposure?
Just exposure. More specific tests, such as spinal fluid immunoassay and DNA
testing of CSF are more definitive.
>Is there a reason you would not treat the disease when the blood test
>is positive but the symptoms are not typical?
If there is a high index of suspicion that the problem is EPM, I would
personally err on the side of treatment.
>Do all horses show the same symptoms (basically) or are there
>different reactions to it?
As above, signs are dependent on the part of the nervous system affected.
>Can it be a re-occuring disease if the horse was exposed but not treated?
Well, if the horse had the disease and was not treated, it would be
"persistent", not "recurrent".
>Could a horse be blood positive, show mild symptoms and then "get over
>it" with no treatment?
The horse could be seropositive and never develop clinical signs, but I don't
know about a mild case--I would probably treat anyway.
>Are there any books with good information about this disease?
Probably no books yet--it's an emerging disease. The March issue of "The
Horse" (formerly Modern Horse Breeding) has a good article on EPM.
>Please help us out with this. I have the distinct impression my vet
>doesn't want to tell me he doesn't know what to do about this - my horse
>has a positive blood test, so does the horse next to him, they both recently
>were moved to NC and have shown a sore back/vague hind end lameness
>kinda thing. Blood was drawn to humor the other owner... boy were they
>surprised with 2 positives. Still, they keep insisting they've only been
>exposed.
Get a second opinion if you are uncomfortable with this. Or request your DVM
do a CSF tap and submit it for testing. It is true that the blood test only
indicates exposure, not infection. Symptoms are more reflective of a
neurologic problem than "lameness" per se, though I agree a slight
neurologic defict could be mistaken for lameness. Has your DVM done a
thorough neurologic exam?
>Gayle Allor
Good luck--
C.M.Newell, DVM
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