I thought once a stallion is vaccinated for EVA that he will always show a positive even though he never had it, was simply vaccinated for it.
he will show positive titers - correct - so its imperative that blood is pulled BEFORE that first vaccination is given and another sample held back in case something happens to that first sample, and the testing is done with an accredited, reputable lab proving the stallion was negative prior to the vaccination being given to him. This way, if there is any question at all as to his EVA status, that first blood sample is proof that he was/is negative and its only the titers that are showing a positive reading