EHV 1 Outbreak: General Equine Disease Prevention & Biosecurity Guidelines
Updated 04/21/2026
The Equine Disease Communication Center (EDCC) has issued an alert regarding a recent competition in Culpeper, VA. More information can be found on the EDCC website.
HITS has issued this biosecurity update statement.
Source: Maryland Department of Animal Health Facebook Page
There has been a confirmed outbreak of Equine Herpes Virus (EHV-1)/ Equine Herpes Myeloencephalopathy (EHM) in horses that attended or were associated with recent competitions in Texas and Oklahoma. Several cases have been confirmed and many are still pending investigation. These events took place from November 5 - November 9.
There has been one confirmed but unrelated case in Maryland. Owners of horses who have recently traveled to Texas, Oklahoma, or other events where EHV exposure may have occurred are encouraged to reach out directly to the Maryland Department of Agriculture (MDA) for guidance regarding isolation and monitoring. Here is some helpful information to stay informed, as well as some suggested guidelines for spread prevention. Always consult with your veterinarian about what is best for you and your horse.
How is EHV Spread?
EHV‐1 is spread from horse to horse through contact with nasal discharge or spread as aerosol droplets. Infected horses may not show clinical signs of the virus but may still act as carriers. Horses can also contract the virus by coming into contact with contaminated surfaces such as stalls, water, feed, tack, and transport vehicles. People can spread the virus from horse to horse by contaminated hands and clothing. It is important for owners to watch for signs and symptoms and practice biosecurity measures.
EHM Signs & Symptoms
Equine Herpes Virus 1 (EHV-1) has four forms, causing respiratory infection, neonatal infection, abortion, or neurological signs. The last form can cause Equine Herpesvirus Myeloencephalopathy (EHM).
The following clinical signs may be associated with EHM (the neurological disease linked to equine herpes virus). These are not specific to EHM and diagnostic testing is required to confirm infection. Consult your veterinarian if you suspect your horse is exhibiting signs or may have been exposed to EHV-1.
- fever of 102.5°F or greater (fever most often comes before
neurologic signs) - nasal discharge
- lack of coordination
- hindquarter weakness
- leaning or resting against a
fence or wall to maintain balance - lethargy
- penile paralysis & urine dribbling
- head tilt
- diminished tail tone
Infected horses that do not show clinical signs act as carriers and can shed the virus.
Biosecurity Practices & Prevention
While the MDA continues to monitor cases in Maryland, this serves as a reminder to brush up on best practices and standard guidance to maintain good biosecurity all year long, especially if you travel between barns or take your horse to shows and events.
If you suspect your horse has been exposed or infected (consult with your veterinarian first!)
- Exposed horses should be isolated for 21 days after last known exposure.
- Appropriate isolation includes restricted access to other horses, avoiding the sharing of equipment or personnel, and utilization of protective barrier precautions.
- Exposed horses should be monitored twice daily for elevated temperature (above 101.5oF), respiratory signs (nasal discharge, coughing), and for clinical signs consistent with equine herpes myeloenceophalopathy (neurologic symptoms including inability to stand, difficulty walking, lethargy, and urine dribbling).
- If elevated temperature, respiratory signs, or EHM-compatible clinical signs are noticed, contact your veterinarian.
General Precautions (include but are not limited to)
- Monitor your horse for clinical signs and check their temperature daily
- Make sure your horse is up to date on vaccinations
- Wash and disinfect your hands, clothing, shoes/boots, tack and equipment between barns/facilities
- Do not share tack, equipment, brushes, stalls, hay nets, water & feed buckets, or other stable supplies between horses to avoid cross-contamination
- Limit or restrict moving or traveling with your horse to events or other barns
- Ensure your vet, farrier, trainer, and other professionals traveling between facilities are disinfecting and following other recommended protocols before and after visiting your horse.
- Isolate any new horses arriving to your barn (ideally for 2-3 weeks)
- Regularly clean & disinfect surfaces such as stall latches, light switches, door knobs/handles & mucking tools
Resources & Additional Info
Maryland Department of Agriculture: Multi-State Equine Herpes Outbreak Notice
Biosecurity Instructions for Grooms & Caretakers (English & Spanish)
Biosecurity Toolkit for Equine Events
MDA Guidelines to Keeping Horses Healthy During Weekend Events
Maryland Department of Agriculture State Veterinarian's Office
World Horse Welfare - Keeping Your Horse Healthy
Any information provided here is not intended to be a comprehensive guide nor taken as veterinary advice. Always consult with your veterinarian to determine best monitoring and treatment actions.
