A case-based approach to the challenges of equine protozoal myeloencephalitis management

"Jewel", a 1.5 year old Thoroughbred colt, presented to Cornell's Equine/Farm Animal Hospital emergency service on 9/18/06 for recumbency and neurologic signs. On presentation, the colt was down on the trailer, depressed and minimally responsive. Physical examination revealed no systemic abnormalities other than his neurologic signs. The neurologic abnormalities were consistent with multi-focal disease and primary differentials included Rabies, Equine Protozoal Myeloencephalitis (EPM), Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV). Serum and CSF Western Blot were positive for EPM, but tests were negative for EEE and WNV. The colt stood occasionally for prolonged periods of time, however by the sixth day of hospitalization his condition worsened and Jewel was euthanized on 9/23/06. The brain was negative for rabies and the histopathology revealed lymphocytic perivascular cuffing in the brainstem, consistent with EPM. This case study will be used to review and discuss the etiology, clinical features, diagnosis, prognosis, and treatment of EPM