Re: EPM in feeds?

[Sue Brown <sbrown@wamedes.com>]

At 11:59 AM 2/22/2000 -0500, CMKSAGEHIL@aol.com wrote:
>Yep, as I discussed in my last post, it doesn't take much to kill the 
>organism, and the extruding process pretty well cooks the feed.  Where you 
>live, if you were feeding an extruded feed, I'd suspect your mare got it
from 
>hay or pasture--would be a more likely source anyway where you have opossums.

Thanks for the info, Heidi.  That was my opinion also...and decided this was
not the area to have a horse who had a susceptibility to EPM!
 
> The Willamette valley has an exposure rate of better than 50% by serology 
>(remember that "positive" serology only means the horse has been exposed,
not 
>that he actually "has" the disease) and in some areas of Kentucky, studies
in 
>TB youngsters have shown exposure rates over 90%.  

I had read, at one time, that if you tested all of the TBs in the country,
you'd find an exposure rate of at least 50%.  Of that exposure rate, only
something like 2% would develop the disease.  (Don't quote me tho, I'm not
exactly sure of the last number...but it was a fairly small percentage...and
the info I saved on it is on a ZIP floppy, currently not hooked up to this
computer.)

The vast majority of these 
>horses never do have clinical EPM--those that don't get it have some 
>combination of healthy meninges so that the organism does not have a "ready" 
>area to set up housekeeping and a good immune system to simply deal with the 
>organism directly.  

It was felt that my horse had a compromised immune system since, when I
eventually had to put her down, she had (by spinal tap analysis) both EPM
and a
strain of herpes encephalitis and had not had any problems as a youngster in
regard to injuries or Wobblers Syndrome.  It was a complete nightmare that I
hope to never have to go thru again!  I made it thru 6 months of expensive
medication after our first attack (with no gait abnormalities or other
residuals at that time)...but the she was either reinfected or had hibernating
residual protozoa that reattacked several months later.  I certainly learned a
lot about EPM at that time...definitely more than I really wanted to know!

Sue 

"If all you can do is what you've always 
done, then all you can be is what you are right now."
                              author unknown

sbrown@wamedes.com
Tyee Farm
Marysville, Wa.