EHV-1 Outbreak Linked to Texas WPRA Event Prompts Multi-State Biosecurity Measures

Inside the EHV crisis: how one event sparked a nationwide warning.

An Equine Herpesvirus-1 (EHV-1) outbreak, including several cases showing neurological involvement, has been traced to a major WPRA event in Waco, Texas, prompting urgent action from state animal health officials, veterinarians, and event organizers. The multi-day competition, held in early November, drew horses from across the region. Since the event concluded, multiple horses have tested positive for EHV-1, and several have developed the more severe form known as Equine Herpes Myeloencephalopathy (EHM).

The Texas Animal Health Commission (TAHC) is leading the epidemiological investigation, coordinating with private veterinarians and the management of the event facility. Although the total number of exposures is still being evaluated, officials have confirmed that several horses showing clinical signs were present at the event, making it a primary point of transmission. More cases have been confirmed in As the virus does not infect humans, no human health concerns have been reported, but consequences for the equine community are significant.

EHV-1 is a highly contagious virus that circulates widely in the horse population, but certain strains can cause severe illness. While some horses exhibit only fever or mild respiratory signs, others develop neurological symptoms such as hind-end weakness, incoordination, loss of tail tone, and difficulty rising. Horses may also shed the virus without outward symptoms, making detection and containment more challenging.

The neurologic form, EHM, is especially dangerous. Once the virus affects the spinal cord or brain, horses can deteriorate rapidly. Some may recover with intensive care, but others may experience lasting deficits, or be unable to stand without assistance.

Symptoms of EHV

Clinical signs of EHV vary. Some horses may show no outward symptoms, while others develop severe respiratory or neurological disease. Common symptoms include:

• Fever (often the earliest and most consistent sign)
• Nasal discharge
• Cough
• Depression or lethargy
• Difficulty urinating
• Hind-limb weakness or incoordination
• Stumbling or ataxia that may progress to all four limbs
• Loss of tail tone
• Head tilt
• Recumbency (down and unable to rise)
• Abortion in pregnant mares

Because the early signs can be subtle, consistent temperature monitoring and prompt veterinary evaluation are critical during an outbreak. When EHM appears in a multi-horse environment such as a show or race, the risk of widespread transmission increases dramatically.

Investigators believe that the virus likely spread through a combination of direct and indirect transmission routes common at equine gatherings. Horses frequently share warm-up areas, alleyways, stalls, wash racks, and equipment, creating ample opportunities for exposure. EHV-1 spreads through nasal secretions, aerosolized droplets from coughing or sneezing, contaminated surfaces and tools, and even via human handlers who inadvertently carry the virus on clothing, boots, or hands.

Because some horses attended the event while incubating the virus, or possibly shedding without symptoms, exposure may have occurred before clinical signs became apparent. The size and pace of the event meant that many horses came into close proximity, heightening the chance of transmission.

Once positive cases were confirmed, affected horses were placed under quarantine following TAHC protocols. The premises that housed exposed horses are now subject to movement restrictions, and veterinarians have been advising owners on strict monitoring procedures, including twice-daily temperature checks. A temperature of 101.5°F or higher is considered a red flag and should prompt immediate veterinary evaluation.

Veterinary clinics across Texas have increased diagnostic testing capacities, particularly PCR testing for EHV-1. Horses exhibiting abnormal gait, fever, nasal discharge, or behavioral changes are being tested and isolated pending results. Farms and boarding facilities that have horses returning from the event have also been asked to implement on-site isolation for at least two to three weeks.

All equipment and shared spaces, stalls, buckets, tack, trailers, grooming tools, and even high-touch surfaces like stall latches and door handles, are undergoing aggressive cleaning and disinfection. Many barns have implemented personnel-level biosecurity measures, requiring handlers to wash hands between horses, sanitize boots, and avoid sharing supplies.

The outbreak has placed the broader Texas equine community on alert. Barrel racing, like other high-traffic equine sports, relies heavily on travel and close contact among competitors. A single positive case can have ripple effects across multiple states as horses return home or continue on to other competitions.

While vaccination cannot completely prevent EHV-1 or EHM, it may reduce viral shedding and lessen the severity of symptoms. Veterinarians are urging horse owners to review vaccination schedules and maintain overall herd health to minimize risk factors.

Stress is also a known trigger for viral reactivation. Horses traveling long distances, competing frequently, or transitioning between different environments are more vulnerable. This outbreak has renewed calls within the industry for increased planning around horse movement, improved hygiene protocols at events, and better isolation practices—especially at shows that draw participants from large geographic areas.

Horse owners whose animals attended the event, or who have been in contact with exposed horses, are encouraged to take the following precautions immediately:

• Isolate returning or exposed horses to prevent contact with the rest of the herd.
• Check temperatures twice daily and log any changes.
• Limit horse movement until monitoring periods have passed.
• Disinfect gear and trailers thoroughly.
• Wear dedicated clothing and boots when handling isolated horses.
• Consult a veterinarian promptly if any clinical signs appear.

Even owners with horses that did not attend the event are being urged to strengthen routine biosecurity, as outbreaks can spread beyond their original clusters.

The TAHC will continue providing updates as tracing, testing, and monitoring progress. Event organizers have pledged full cooperation with the investigation and are reviewing procedures to enhance biosecurity at future gatherings.

This outbreak serves as a pointed reminder that equine health relies heavily on proactive management. While EHV-1 is not new, the speed with which it can spread, and the severity with which EHM can strike, make vigilance essential. With coordinated action, transparent communication, and strict adherence to preventive measures, the Texas equine community aims to contain the current outbreak and reduce the likelihood of future incidents.