Two horses in Cooke County, Texas have tested positive for the contagious virus Equine Herpes Myeloencephalopathy (EHM). EHM is an emerging equine neurological disease related to the Equine Herpes Virus (EHV-1).

According to the new Equine Disease Communication Center (EDCC), the disease alert unfolded late on the evening of May 24, when a Cooke County breeding farm reported that a mare was infected with EHM, based on a polymerase chain reaction (PCR) analysis from a blood sample. 

The notification reads, “The horse began showing acute neuro signs when the test was performed. A quarantine was issued and no movement has taken place in or out of the barn.” 

The following day, a second horse tested positive. EDCC reported that the diagnosis of the second horse was based on a nasal swab taken after the horse began showing slight neurological deficits. Both animals are under strict care. 

“(The) affected horses have been isolated and strict biosecurity measures are in place,” EDCC shared. “Temperatures are being monitored and no other fevers or clinical signs have been noted in the barn of 40 horses.” 

EHV has several types. It is very easy to be confused about the difference between EHV and EHM, since EHV-1 alone may also cause some neurological symptoms. A laboratory test is needed to determine EHM. EHM is an emerging equine disease and is under close study.

Neither neurologic EHV-1 or EHM are covered by EHV vaccination or any other vaccine currently approved in the United States.

Cooke County is located due north of the Dallas-Fort Worth metropolitan area. The county straddles I-35 and touches the Oklahoma border. Among the well-known horse communities in the county is Gainesville, but horses can be found across the county. While the area is known for its Quarter horse and Paint horse farms, the area is home to a wide range of breeds, and both pleasure and racehorses can be found there. 

Download the Texas Animal Health Commission information sheet on EHM.