EC can be a difficult disease to diagnose. Many vets learned that the first sign of EC is head tilt, which is not true. It is a parasite that enters through the GI tract. An active infection starts in the kidneys, and replicates itself there, which can cause problems with the urinary tract as the rabbit is shedding EC spores in its urine. It can also affect hind leg mobility in this stage of the disease. Eventually it works its way to the brainstem, where it causes head tilt, or "wry neck," which used to be what EC was called. At this point, the disease is much harder to treat as it is difficult to get many drugs into the brain to kill the parasite.
This article is very good but a bit long:
http://www.rabbit.org/journal/3-2/e-cuniculi.html
An EC titer will most likely be positive for almost any bunny, and beyond being positive it is difficult to tell whether or not it is indicative of an active case. It is controversial as to whether a high titer for EC means that there is an active case or not, as discussed in the article mentioned (and pretty much any article I've seen). This is probably what your vet knows. I have read, however, that Randy has had success treating several rabbits with EC, and he believes in checking the EC titer to determine the progress of the disease (PLEASE correct me if I'm wrong--don't want to put words in anyone's mouth).
I think the real concern here is that we don't know what's causing the sludge because it doesn't appear to be dietary, and I don't think a bacterial infection is suspected for Chase (yes or no?). I don't think it's very common for a rabbit to have sludge for the rest of their life--sludge means some part of the urinary tract isn't working correctly and that needs to be addressed. That's why we have been reccomending an EC titer.
Big HUGS and healing wishes~~
