Research shows that early diagnosis and treatment of EPM results in a much higher chance of full recovery. Identifying it early requires a knowledgeable owner. In just 30 minutes of reading on prevention and symptoms, an owner can help put their horse into those better statistics.
My horse was treated for EPM last year, although I'm still not sure he actually had it. His symptoms were similar, but he didn't have all of them, and they never actually tested. They just treated. He did completely recover from whatever it was and it cleard up his roaring problem at the same time, so I'm not going to complain. Whatever it was, we did catch it early, so I do agree that early treatement is key.
I've heard that if you feed a horse that has EPM things high in vitamin E (dry roasted almonds, wheat germ oil . . . ), that it slows the progression of the disease to the central nervous system. A horse at my old barn was diagnosed w/ EPM. Her owner did care and didn't have the money (single mom, multiple jobs, 2 kids) and they just left her in her stall, so my friend and I snuck her the almonds when no one was watching. Turns out she had broken her neck and the symptoms were similar to EPM.
Best treatment is to try to avoid it if at all possible - remove any reason for junk critters to hang around the barn/pasture, and I trap aggressively nearly all year around - our area of MI is fairly swampy in spots where it isn't wooded or farms, and makes great hiding spots for possum & raccoons. They're rotten filthy animals anyhow, so it's no problem for me to dispatch them. ;)
They aren't filthy animals. I've raised lots of possums ;)
But you are right that prevention is best managed by not making your place hospitable to possums (raccoons aren't an issue). Don't leave cat/dog food out and store feed and hay in areas where possums simply CANNOT get to it.
EPMhorse, are you a member of the EPM list on yahoo?