A widespread outbreak of a neurological horse virus has rocked the U.S. equine sector, leading to event cancellations, travel restrictions, and increasing anxiety among horse owners and veterinarians.
The Equine Disease Communication Center (EDCC) has linked the surge in equine herpesvirus myeloencephalopathy (EHM) to the Women’s Professional Rodeo Association World Finals and Elite Barrel Race, which took place Nov. 5-9 in Waco, Texas.By Nov. 22, 19 verified EHM cases were traced to the event, along with other non-neurologic equine herpesvirus-1 (EHV-1) instances in Oklahoma, Washington, and Arizona.
Infections have appeared in Texas, Oklahoma, Louisiana, South Dakota, Colorado, New Mexico, Arizona, and Washington. EDCC data show Texas has the most neurologic EHM cases, 11, and two animals had to be euthanized. A lone verified EHM case in Maryland on Nov. 18 has not been linked to the Waco outbreak.
EHV-1 causes respiratory ailments, though certain variants lead to neurologic complications from swelling and clotting in the brain and spinal cord.
Symptoms include high temperature, rear leg weakness, edema, convulsions, and urinary incontinence. The EDCC states that 60 percent to 70 percent of affected horses recuperate after treatment and quarantine.
EHV-1 is not a threat to humans and isn’t transmissible between species, though individuals can inadvertently transfer it among horses. Transmission occurs through direct animal interaction or contaminated objects such as containers, tools, and harnesses.
Authorities say the current outbreak is a “particularly aggressive strain,” according to the magazine Chronicle of the Horse.
The Texas Animal Health Commission said the extent of this outbreak “is not yet fully known,” noting the swift spread and “a concerning number of mortalities” documented.
Concern centers on horses that left the Texas venue prior to the onset of symptoms. Some competed in other contests in the Southwest, possibly prolonging the exposure period and affecting new sites. The standard latency spans two to 10 days, when animals might seem healthy yet still excrete the pathogen.
Nevertheless, USEF advised that horses involved in barrel racing or rodeo gatherings “should remain on the premises and be monitored.”
Numerous equine gatherings have been delayed or canceled. Texas Rose Horse Park suspended all equine operations until Dec. 2, considering it “the most responsible action right now to limit further spread.”
In Florida, TerraNova Equestrian Center rescheduled a training session, while the World Equestrian Center–Ocala canceled a barrel racing competition scheduled for Nov. 26-29 “out of an abundance of caution.”
The National Assembly of State Animal Health Officials has also paused extended equine certificates of veterinary inspection, requiring horses crossing state lines to secure updated paperwork.
Veterinary experts and authorities recommend checking horses’ temperatures twice daily and enforcing at least a 21-day quarantine for those returning from competitions.
