[question name="Luanne"]I am very excited to hear that there is a vaccine for EPM (equine protozoal myeloencephalitis)! Three and a half years ago, I had to put down an outstanding colt who was only 14 months old. He suffered from both CVM (cervical vertebral myelopathy) and EPM. The vet did not seem to feel that the EPM was severe and probably was a new infection. Since the colt came from New Mexico in the desert area at six months of age, it is not likely that he contracted it there, but more likely that he contracted it in his new home in Southern California.

To my question: if I vaccinate my horse against EPM, does it negate our most widely used test, the Western blot? Will a horse test positive for EPM if he is vaccinated assuming he was negative prior to vaccination?