In the U.S., the EHV outbreak 2025 is raising urgent concerns among equine professionals as several confirmed cases of neurological disease tied to equine herpesvirus type 1 (EHV-1) have emerged in multiple states. One case in Sussex County, New Jersey involved a 20-year-old mare euthanized after developing neurologic signs, prompting immediate quarantine of her premises. Meanwhile, a separate incident in Washington County, Minnesota triggered isolation of 60 exposed horses following a confirmed neurologic form of the virus earlier this year. These developments mark real, current threats to horse health and movement nationwide.
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What’s Happening in the Field
The outbreak covers several U.S. states with confirmed occurrences of the neurologic form of the virus—also called equine herpesmyeloencephalopathy (EHM).
- In New Jersey, the Department of Agriculture quarantined a property after one mare developed neurological symptoms and was confirmed to have EHV-1. The case developed on August 3, 2025.
- In Minnesota, a 16-year-old mare exhibited neurologic deficits on April 22, 2025, and tested positive for EHV-1; the local animal health board quarantined 60 additional horses at the same facility.
These incidents reflect active spread and serious outcomes. The neurologic variant of the virus has greater risk and demands heightened biosecurity and immediate response.
Understanding the Virus and Its Risks
EHV-1 is a highly contagious viral infection among horses. The outbreak underscores two primary forms:
- Respiratory form: Fever, nasal discharge, cough—often milder.
- Neurologic form (EHM): Hind-end weakness, loss of tail tone, urinary retention, stumbling, and sometimes death.
During this recent outbreak period, cases of the neurologic form have triggered dramatic measures. The virus can spread via direct contact (nose to nose), contaminated equipment, trailers, and communal spaces. Horses may shed virus even if they appear healthy, raising the threat of undetected spread.
Vaccines exist for EHV-1 and EHV-4 in respiratory or abortion-related disease but offer limited protection against the neurologic form. That makes containment and monitoring critical during the 2025 outbreak.
Timeline & Key Episodes in 2025
| Date | Location | Event Description |
|---|---|---|
| April 22 | Washington County, MN | Horse with neurologic signs; positive EHV-1 test; 60 horses quarantined. |
| August 3 | Sussex County, NJ | 20-year-old mare confirmed EHV-1 neurological disease; premises quarantined. |
| Ongoing | Multiple states | Monitoring continues for exposed horses and secondary spread. |
This timeline illustrates how the outbreak is active throughout 2025 and affecting diverse U.S. regions.
Impact on Horse Movement and Events
The outbreak has immediate implications for U.S. equine competitions, stables, and transport logistics. When a neurologic EHV-1 case surfaces:
- Horses on the affected premises cannot move in or out until clearance is confirmed.
- Nearby farms often enforce quarantines for 14–21 days from the last fever-or-positive test.
- Events may require additional checks, such as negative PCR tests, temperature logs, or vaccination documentation.
For trainers, owners and event managers, the outbreak adds another layer of risk. Travel, shared equipment, communal watering points and large gatherings of horses increase the chance of virus introduction or spread.
Biosecurity Measures During the Outbreak 2025
Given the nature of the outbreak, the following practices are essential:
- Monitor every horse’s rectal temperature at least twice daily. A spike (≥102°F) may signal infection.
- Isolate horses returning from shows or new arrivals for at least 21 days.
- Use individual feed and water buckets; disinfect tack, buckets and trailers thoroughly.
- Avoid nose-to-nose contact between horses; keep stall spacing adequate and separate feed/water points.
- At events, limit cross-contact between stables and require negative tests or health certificates.
These steps are critical to prevent spread during the 2025 outbreak.
Treatment and Prognosis
There is no cure for EHV-1, and the neurologic form has variable outcomes. Treatment typically includes:
- Supportive care (fluids, anti-inflammatory medications).
- Antiviral agents may reduce viral load and shedding when implemented early.
- Strict protocols for horses showing neurologic signs; in severe cases euthanasia is chosen to prevent suffering and further spread.
Horses that recover from the neurologic form may never fully regain previous function. The 2025 outbreak underlines the urgency of early detection and swift action.
Read also-What Is EHV 1 in Horses? A Complete Guide for U.S. Owners in 2025
Why the Outbreak 2025 Is Particularly Concerning
Several factors make this situation more serious:
- Multiple states reporting neurologic cases in 2025, demonstrating broad geographic risk.
- Presence of silent shedders—horses that appear healthy but spread virus to others.
- Large events and trailer movements that amplify contact points.
- Veterinary and management burdens of quarantining large numbers of horses and implementing tracking protocols.
The combination of these makes the outbreak a high-priority issue for the U.S. equine community right now.
What Owners and Facilities Should Do Now
If you own, board, train or manage horses in the U.S., these steps are recommended during the outbreak:
- Stay alert for any fever or neurologic signs—even mild hind‐end weakness or loss of tail tone.
- Keep detailed travel logs, especially for show or competition horses.
- Review vaccination status and ensure your herd is up to date for EHV-1/EHV-4.
- If exposed or suspect infection, work with your veterinarian to test, isolate and monitor all contacts.
- Chain your biosecurity practices: disinfect trailers, tack, buckets; limit personnel; enforce stable hygiene.
Acting proactively can reduce infection risk and limit disruption.
Looking Ahead: Mitigation for Future Risk
In the months ahead, managing the outbreak will involve:
- Enhanced testing and rapid response at the first sign of temperature or neurologic changes.
- Stronger bio-isolation plans for events and travel.
- Better data collection on shedders and transmission dynamics.
- Owners, trainers and vets collaborating more closely to standardize protocols across states.
If these measures are sustained, the U.S. equine industry can reduce the impact of the outbreak and protect horses long term.
Final Thoughts
The outbreak in 2025 serves as a critical reminder of how serious and unpredictable EHV-1 can be. With confirmed neurologic cases in multiple U.S. states and the ever-present threat of silent transmission, vigilance, strong biosecurity and swift action are more essential than ever.
We invite readers to share their experiences, ask questions and stay informed as this evolving situation develops.