I started experimenting with my new bunny yesterday with Panacur. And I'm kinda scared to tell my vet honestly. Doctors of all sorts frown on self treatment these days. Don't they? I think most of them have a real unhappiness with all the medical advice floating around the net.
The thing about e. cuniculi is there is no consensus on what to do about it. I think my vets position is that the immune system will fix it until it doesn't. Most wont show symptoms anyway. It isn't even known if treating it will kill all the protozoa or if you need to retreat them from time to time. Some people think you should treat no matter what just in case.
I've taken the position that I would rather try to treat her now while she is healthy. I think the immune system probably keeps it in check (usually). But if their immune system gets a little weak it probably takes advantage of that weakness and multiplies.
I'm sort of in this weird position between vets and breeders. The breeders want to treat aggressively, and the vets not so much. Even the very respected house rabbit vet who did the necropsy on my last bun only recommended treatment if the rabbit showed signs. The hard thing about that though is once they show signs you probably don't have time to get the blood work back before the rabbit is dead. Which why I tested my new girl as soon as her little body was big enough to give blood. When they are sick - they are not foolin'- and time is short if you can't fix it fast.