I was told my filly has opposums disease. What is it and how do I treat it?

I'm assuming since you wrote this a month ago- you may have already began treatment on your filly or put her to sleep. The disease is known as EPM -and i'm too tired to remember what the letters stand for but you can find that online. It is caused by the horse injesting feed/forage containing opossum feces. I just had to throw out a bunch of hay and grain that I found a opossum is. Horses can be exposed to it and not catch the disease but they sometimes do as well. Treatment is expensive and you'd need a vet out. I'm not sure but since she's already experienced that level of paralysis it may be to late for treatment.