Re: EPM in feeds?

[CMKSAGEHIL@aol.com]

In a message dated 2/21/00 10:23:05 PM Pacific Standard Time, 
sbrown@wamedes.com writes:

<< Just read this one...isn't steam rolling a normal processing?  Does this
 mean that the protozoa is fairly fragile in the heat?...the grain wouldn't
 have to be nearly sterilized in order to kill it?  Janie (my mare with EPM)
 was fed an extruded feed...looking back, I don't know if there was enough
 heat in the processing to make it pass.  It was a moot point living near
 the woods, however. >>

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. 
 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%.  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.  Barry Grant tells me that clinically, they see many of 
the EPM cases in horses with either mild (or previously undetected) cases of 
Wobblers Syndrome or in horses that have had some sort of mild spinal 
trauma--the theory is that the protozoa is opportunistic and has a much 
better chance of attacking tissue that is already somewhat damaged from some 
other process.  Others have mentioned that they feel many cases are in horses 
that are a bit less immunologically competent than their peers.  I'd suspect 
both of these things are variables that would increase the risk.

Heidi