NEW JERSEY DEPARTMENT OF AGRICULTURE – MEMO
Multi-State Equine Herpes Myeloencephalopathy Outbreak – Texas, Oklahoma, Louisiana
(TRENTON) – On November 18, 2025, state counterparts in Texas announced confirmation of neurologic EHV-1, Equine Herpes Myeloencephalopathy (EHM) in two horses, with several suspect cases. These cases have been linked to attendance at equine competitions in Texas, resulting in additional confirmed cases in horses in Oklahoma and Louisiana. In Texas, multiple horses, either diagnosed with EHM or with an epidemiologic link to the outbreak, have presented with severe illness. This outbreak is reported to involve a highly virulent EHV-1, at the center of multiple confirmed and suspect cases, as well as numerous horse deaths. Tracing of equine movements is currently underway by state animal health officials within affected states. There is currently no known impact on New Jersey resident equine. New Jersey had one EHM case in 2025, confirmed in a Sussex County mare in August, unrelated to the current multistate outbreak.
To assist in the discovery of epidemiologic, the New Jersey Department of Agriculture is sharing the following equine competition events in which the index and subsequent cases are known to have occurred:
- WPRA World Finals in Waco, Texas, from November 5-9, 2025
- BFA World Championship at Lazy E Arena in Guthrie, OK, from November 17-22. As of November 19, this event was cancelled.
- 377 Arenas weekly barrel race in Stephenville, TX, on November 10 or 17, 2025
Immediately report to the NJDA any known NJ equine travel to the above premises on the specified dates to allow for further investigation and provide guidance on monitoring and isolation. As the multi-state disease investigation continues, additional high-risk movements may be determined, and the NJDA will provide updates as necessary. Generally, any horse or herd of concern should be isolated for 21 days, with twice-daily temperature checks, monitoring, and reporting of suspect cases. Call the NJDA Division of Animal Health to report: 609-671-6400.
All confirmed or suspect cases of EHM should be reported to the State Veterinarian to enable isolation, swift tracing, and movement control. With the occurrence of this evolving equine disease event, now more than ever, equine owners, barn managers, and equine event organizers should be reminded of critical biosecurity measures. Veterinarians involved in equine competitions should review entry requirements and assess the current equine disease status regionally, nationally, and for the specific riding disciplines. Horses returning from off-site activities in which there was potential exposure to other horses and equipment should be closely monitored for illness, including fever and respiratory and/or neurologic signs. NJDA veterinarians are available to provide input on site-specific biosecurity strategies, consult on planning stages for a disease control plan, and provide protocols for handling sick horses.
Online resources for equine biosecurity and disease control planning:
- AAEP General Biosecurity Guidelines: https://aaep.org/resource/general-biosecurity-guidelines/
- AAEP Infectious Disease Guidelines: Equine Herpesvirus 1 & 4: https://aaep.org/wp-content/uploads/2024/02/EHV1-4-guidelines-2021.pdf
- Biosecurity Toolkit https://www.cdfa.ca.gov/ahfss/Animal_Health/Equine_Biosecurity.html
The Equine Disease Communication Center (EDCC) provides the latest on communicable equine disease in North America and contains resources for both veterinarians and horse owners: https://www.equinediseasecc.org/
EHV-1 spreads quickly from horse to horse, has high morbidity, and can cause a wide range of symptoms, from a complete lack of clinical signs to respiratory problems, especially in young horses, and spontaneous abortions in pregnant mares. Neurotropic EHV-1 (EHM) can result in debilitating and grave neurologic effects. Transmission of the virus is mostly via
direct contact with infected materials; therefore, tack must not be shared between horses, and biosecurity measures must be utilized. The virus is endemic in the country, and although highly infectious, it does not persist in the environment and is neutralized by hand soap, alcohol-based hand sanitizers, and sunlight.
It is advised to communicate with destination states for interstate equine travel requirements, for which some states may implement additional control measures of horse movement during this higher-risk time period.
EHM, like other viral diseases affecting horses’ neurological systems, must be reported to the state veterinarian within 48 hours, and a neurologic disease worksheet must be completed for each case reported. The worksheet is available at the following website and, once completed, can be faxed or e-mailed to the Division.
https://www.nj.gov/agriculture/ahdl/sample/
| EEE | PCR (no charge)
Whole blood PTT */CSF**/brain tissue |
ELISA (no charge)
1 ml serum, w/cold pack |
1-2 days (PCR)
2-3 days (ELISA) |
| WNV | PCR (no charge)
Whole blood PTT */CSF**/brain tissue |
ELISA (no charge)
1 ml serum, w/cold pack |
1-2 days (PCR)
2-3 days (ELISA) |
| EHV-1 | Neurologic PCR ($60.00)
Whole blood PTT/Nasal swab, brain tissue |
EHV-1 SN titer ($20.00)
1 ml serum, w/cold pack |
1-2 days (PCR)
4 days (titer) |
*PTT-purple top tube **spinal fluid
Contact the laboratory at (609) 406-6999 or via email: jerseyvetlab@ag.nj.gov
Division of Animal Health
Phone: (609) 671-6400
Fax: (609) 671-6413
Animal Health Diagnostic Laboratory
Phone: (609) 406-6999
Fax: (609) 671-6414