My horse did the Oroquin 10 course of treatment and made a full recovery. His EPM came on very fast, within a few days he went from being completely sound and full of life to staggering around, barely able to walk.
I already had a vet appointment for routine stuff, and the vet guessed it was probably EPM, and took blood to have it tested. The next day I called the vet and wanted to start a course of treatment as the horse was getting worse by the hour. My vet said that he wasn't supposed to prescribe medication until he got the results of the test back, and that would be on Thursday. I said, "The horse will be dead by Thursday." The vet made an exception, had the Oroquin 10 compounded in Ocala, and I drove the hour and 45 minute drive each way to get the medication and gave it to him the minute I got home.
My horse started to recover within about 2 hours of the first dose. He made a complete and full recovery from the Oroquin 10. Everyone told me the EPM would ultimately come back, but I hoped they were wrong, my horse was so sound and healthy. The vet said he had never seen anything like it, my horse was so bad off when he started treatment. He was 100% sound and able to do everything he could do before the EPM hit him.
I got to enjoy my wonderful boy for 2 1/2 more years when the EPM did come back, even faster than before. He went from being just a tiny bit "off" to being dead in 3 days.