Equine herpesvirus (EHV) and its neurologic form, Equine Herpesvirus Myeloencephalopathy (EHM), have become a focus of attention for horse owners. An outbreak started in Texas but has the potential to move across the country unless we are educated about the virus and how to prevent it from spreading.
What Is EHV?
EHV is a common virus that horses encounter early in life and they can become silent carriers, meaning they show no obvious symptoms but can still shed the virus. Stressors such as long trailer trips, competitive events, or changes in group housing can weaken a horse’s immune system and allow the virus to emerge from dormancy.
When EHV becomes active, you might see signs you’d expect with any other respiratory bug, like a fever, clear nasal discharge, or lethargy. This is typically EHV-1 or EHV-4, a contagious respiratory disease that’s spread through the air or on shared equipment like buckets and brushes.
Unfortunately, EHV-1 can sometimes take a much more serious turn, causing neurological problems via a condition called Equine Herpesvirus Myeloencephalopathy (EHM). This form can affect a horse’s coordination, making them wobbly or weak in their hind end.
The virus can also cause abortion in pregnant mares. While horses with the abortive or respiratory conditions can often recover, those with severe neurological damage have a poorer prognosis.
How EHV Spreads
The virus spreads through respiratory secretions and contact with contaminated equipment, tack, brushes, buckets and people who have handled an infected horse.
What You Can Do
As a day-to-day practice, wash your hands between handling different horses and when moving between groups. Do not share buckets, brushes, halters, or blankets with new horses without cleaning and disinfecting. Isolate new or sick horses for a minimum of 2 weeks to minimize spread. Isolated horses should not share a fence line or be stalled next to healthy horses. For general horse health, vaccination for EHV 1/4 can reduce the severity and spread of the respiratory forms.
The goal is balanced vigilance: not to panic, but to be proactive. EHV is a common threat, but with a vaccination plan, solid biosecurity, and early veterinary involvement, you can reduce risk and improve outcomes. Every barn and herd has unique risks. Work with your veterinarian to create a prevention plan that fits your horses’ age, temperament, housing, travel, and competition schedule.