Persistence ofand histopathology in horses with equine protozoal myeloencephalitis.

Abstract

Currently, little is known about the exact role ofimmunopathology in equine protozoal myeloencephalitis (EPM), including the ability to persist after anti-protozoal treatment. The main objectives of this study were to determine whetheris present in the CNS in horses with EPM, including previously treated cases, and to evaluate the associated histopathology and immune response. For this study, control (&#x202f;=&#x202f;10) and horses with EPM (&#x202f;=&#x202f;9) were confirmed based on our inclusion criteria. Based on our preliminary data, we classified horses with EPM and clinical signs for >6&#x202f;months as chronically affected (&#x202f;=&#x202f;5) while horses with clinical signs for <6&#x202f;months were classified as acutely affected (&#x202f;=&#x202f;3). Histopathology changes between acute and chronic horses were identified. Identification ofwas performed postmortem using PCR and IHC. Histopathology analysis with IHC identifiedpresence significantly more than PCR (&#x202f;<&#x202f;0.03) when directly compared. Histopathology analysis revealed that horses chronically affected with EPM had increased degenerative changes in their CNS compared to acutely affected horses when necropsy reports were compared. Our study indicates potential important histopathology differences between horses of varying clinical sign duration and the potential persistence ofafter anti-protozoal treatment. Additional studies are warranted to further elucidate the role ofin disease, including the use of "acute" and "chronic" as clinical definitions for EPM.