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Attention Horse Owners and Referring Veterinarians: Information on Equine Herpesvirus Myeloencephalopathy

March 28, 2014

Lloyd Veterinary Medical Center (515) 294-1500

Recent reports of equine herpesvirus myeloencephalopathy (EHM) in Minnesota have raised concerns regarding horses in Iowa transmitting the disease. The Lloyd Veterinary Medical Center at ISU can confirm that a horse has tested positive for equine herpesvirus 1 (EHV-1) within the state of Iowa; however, this horse was negative for the typical strain that causes EHM (neurologic symptoms). There are concerns that the neurologic symptoms may be associated with cases that test positive for EHV-1 but negative for the strain that causes EHM.

Equine herpesvirus myeloencephalopathy can be serious disease in horses. Typical clinical symptoms are fever, neurological signs (incoordination, urine dribbling) and nasal discharge. If any of these are noted, please contact your regular veterinarian. It is important to remember that virus transmission is most often through direct contact between horses. Appropriate precautions are limiting contact with horses displaying any of the signs listed above and instituting good husbandry practices to avoid horse contact with contaminated equipment, clothing and hands.

Immunization against the neuropathogenic strain of herpesvirus that causes typical EHM is not presently available and no vaccine is available that absolutely prevents viral infection with potential development of neurologic signs. However, vaccination against the typical respiratory herpesvirus is recommended for horses actively traveling, showing or competing. For specific risk-based vaccination recommendations in your area, please contact your regular veterinarian.


For additional information, please refer to the following links:

Brochure on Equine Herpesvirus Myeloencephalopathy


Equine Herpesvirus Type 1
and Equine Herpes


If your horse has symptoms and has been in an area where a positive horse has been reported, please contact the Lloyd Veterinary Medical Center at (515) 294-1500.