I want to clarify something I wrote in the last post.  Scout doesn't have EPM.  He tested positive for antibodies to a couple parasites that are now known to be linked to cause EPM. The research results are so interesting.  Opossums are good hosts for this parasite, but birds and cats and others can be hosts also. Horses usually shed these parasites on their own, but sometimes they don't and an infection or inflammatory response happens. 

Now that I have read thru Dr. Ellison's Pathogenes Inc website and blog, I have a much better understanding of what is going on with him.  Even though Scout's results were on the low side of positive, he is now showing some clinical signs of infection and inflammation, such as failing parts of his neuor exam last week.  Remember I had the ELISA antibody test drawn almost 4 weeks ago, because other horses in the barn had tested positive and this thing with the canter showing up suddenly over the past year. Now he's gotten worse since the neuro exam. He just isn't right.
  Sunday we walked down the trail after a lift dusting of snow.  He did  trot at one point on his own, but quickly came back to a walk after taking an odd step after about 10 feet. On our way back home we retraced our steps on the road.  Like I said, there was a fresh dusting of snow and our tracks were plain as could be from when we were heading out the other direction.  His left side tracks were solid hoofprints, front and hind, but the right side tracks were different.  I could easily see a slight "poof" or "drift" before the actual hoofprint.  Scout is now dragging his right front toe.  I leaned over in the saddle and watched him walk.  Sure enough, he was "plowing" the top of the snow with his toe, definitely in front and slightly with the hind.         * Sigh*. 
I called Dr. Marold to keep her informed.  No worries she said.  He'll get better.  Just start the medication as soon as I get it.  Thankfully it arrived today, Tuesday.  So I gave him the first dose this afternoon.  Yesterday, Monday, I spent a couple hours reading thru the Pathogenes site.  Scout is very typical of what other owners and vets are seeing in the early signs of infection.  Scout isn't getting the Oroquin 10, just the top dressing of Decoquinate for 90 days.  You can read all about that here if you like.
http://pathogenes.com/blog/2011/12/11/protocidal/
The thought is, if owners and vets catch the signs early and examine and test and treat if necessary, the infection would never develop into EPM.  I hope Dr. Ellison is correct!

I am so glad to know and work with a vet who is involved and interested  and is open to looking beyond the status quo of treatments.  Even if this doesn't work for my horse, I'm glad others around the country helping with this field trial that will hopefully lead to a vaccine.