Yes. According to the American Association of Equine Practitioners (AAEP) “60-70% of horses aggressively treated (for EPM) show significant or complete reversal of symptoms.” There are some 10%-20% of horses that will suffer relapse.
Aggressively treating EPM can be expensive. Depending on the medications administrated, the treatment period can take as little as 1 month or up to 3-6 months.