Equine Herpesvirus Myeloencephalopathy

Equine herpesvirus-1 myeloencephalopathy: Infectious neurologic diseases which can cause fever along with ataxia or other neurologic signs. One which has been of particular interest and concern over the past ten years is equine herpesvirus-1 myeloencephalopathy (EHM).Whenever this problem is mentioned it often incites fear of serious neurological disease and even death in individual horses as well as and outbreaks with multiple affected horses. The other fear is what happens if my horse or my farm or my show ground or race track is subject to quarantine. Equine herpesvirus myeloencephalopathy is not the only cause of fever and neurologic signs. Understanding and recognizing diseases that cause fever and neurologic signs and knowing how to properly diagnose and treat infectious neurologic diseases, including knowledge of which diseases can be prevented by vaccination is important. In addition, it is critical for veterinarians to understand when to be suspicious of EHM and how to mitigate potential outbreaks. Two of the most common neurologic diseases, cervical vertebral stenotic myelopathy (CVSM) and equine protozoal myeloencephalitis (EPM), do not cause fevers. Therefore, when faced with a febrile and ataxic horse, several possibilities exist. The fever could be due to an unrelated comorbidity; reflective of hyperthermia due to high ambient temperature, pain, or stress; or indicative of an inflammatory, infectious neurologic disease. If there is no evidence for the first two causes, viral and bacterial diseases causing febrile neurologic disease should be considered with particular attention as to whether EHV-1 is a possible cause. EHV-1 is a ubiquitous alpha herpesvirus that is readily and primarily transmitted as a respiratory pathogen, either by aerosolization or direct contact between infected horses or fomites. […]