A diagnosis of EPM is often difficult to confirm. It can be ruled out when a test of either blood serum or cerebrospinal fluid shows a negative result. A positive result using CSF is "highly suggestive" of the disease, while a positive result in a serum sample only proves that a horse has been exposed to the protozoa (Sarcocystis neurona) that cause the disease. In Nate's case, we tested serum. Based on the result and clinical symptoms, it was determined that there is a 90% chance he has the disease. Reason enough to start treatment ASAP.
We've opted to use a product called Marquis, hoping for quicker results than some other treatments offer. Marquis should kill any protozoa present, but it will not repair existing damage to Nate's nervous system. Unfortunately, at this point, there is no way to know how extensive that damage may be.
EPM, like Cushings, affects each horse in a different way, depending in part on where the lesions are and how long the disease went untreated. We also don't know how Cushings may complicate treatment or how EPM may complicate Cushings.
In other words, for every answer we get regarding Nate's case, we get five or ten new questions.
The good news is, for now Nate is doing very well. He's eating well, gaining weight, and his spirit is bright. Last night, in a little burst of energy after hand-grazing, he tried a little lope after being turned back into his small paddock. OK, so it wouldn't have been considered "pretty" to most horse folk, but to us it was a gorgeous sight to see. Nate felt "kick-up-your-heels" good. Even if it turns out he only has a short time left in this life, we know he had that.