Case of Equine Herpesvirus Myeloencephalopathy (EHM) Identified in Vermont

16 April 2021

April 16, 2021 | Montpelier, VT - This week, the Vermont Agency of Agriculture, Food and Markets (VAAFM) Animal Health section was notified that a horse in Alburgh exhibiting neurologic abnormalities tested positive for Equine Herpesvirus 1 (EHV-1), resulting in a case of Equine Herpesvirus Myeloencephalopathy (EHM).  The horse in question is currently under quarantine while the Agency monitors and manages the case with the attending veterinarian.

EHV-1 was recently identified as the cause of equine illness outbreaks in Florida and Europe and has led to the cancellation of several international equine events. No link between the Vermont case(s) and these outbreaks has been discovered.

As a precaution, Vermont horse owners should follow these basic biosecurity measures:

  • All newly-purchased horses or horses that return to Vermont from events should be immediately isolated from other horses and quarantined for at least three weeks;
  • All quarantined horses should be monitored for illness, including fever, cough, lack of appetite, nasal or ocular discharge, and/or swelling around the throat;
  • All quarantined horses should have a temperature taken twice a day during the isolation period, and have separate thermometers for each quarantined horse;
  • If a fever is recorded or signs of illness are noted, a veterinarian should be called immediately.

Horse-to-horse contact is the most common route of transmission of EHV-1, but it can also be transmitted when infectious materials, such as nasal secretions, are carried between infected and non-infected horses by people or on objects such as buckets, grooming tools, tack, etc.  Fever is the most common clinical sign, along with coughing and nasal discharge.  Although EHV-1 infection usually causes respiratory illness, some infected horses can also experience neurologic abnormalities such as incoordination, weakness, or inability to rise, a syndrome referred to as EHM.

Anyone concerned about a potential EHV-1 case should contact their veterinarian immediately. 

For questions, please contact:

Kaitlynn Levine, DVM (she/her/hers)

Assistant State Veterinarian

802-636-7144 |

Contact Information

Agency of Agriculture, Food & Markets

116 State Street
Montpelier, Vt 05620-2901


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