DETECTION AND DIAGNOSIS
A number of tests are currently available that make use of the antibodyantigen bond to determine whether a horse has been exposed to S. neurona or N. hughesi, as well as how recently the infection occurred. All have advantages and drawbacks.
The Western blot is an older method that is still in use. A positive result on a Western blot indicates the presence of antibodies to S. neurona, but it cannot distinguish an older infection from a current, active one. The test may, however, be able to rule out EPM in a horse who has no antibodies. (Currently, there is no commercially available Western blot test to determine exposure to N. hughesi.)
Newer tests identify the quantity as well as the type of antibodies present in the horse’s blood. Higher titers of the antibodies may indicate a more