I am a familiar face in the EPM isle unfortunately lol I treat one of mine yearly just because she had it bad once in the past. My go to for yearly maintenance is usually the levamisole/decoquinate compound for 10 days. Not a fan of rebalance or the toltrazuril/dmso. Any other compounded ones out there that people like ? I've heard Sam Crosby has one but I've never been to him before. 

I don’t want to use anything for just 10 days. I really like the Decoquinate/levamisole/ Vit e mix. It’s about twice as strong as the Pathogenes version and it’s a 30 day treatment. So far, I haven’t had to retreat. 

I haven’t seen good results with the Toltrazuril/DMSO Mix. I feel like the DMSO might help, in some cases, temporarily. I know it’s cheap but I’ve seen several horses it didn’t work on.

MVP makes a product called Eclipse PM that is designed as supportive treatment for EPM. It has Cinchona BarK extract in it along with Vitamin E and Lysine. Cinchona Bark extract is an antiprotozoal that is used to treat malaria (also caused by Protozoa) in humans. You might consider using it on your mare.