The Texas Animal Health Commission (TAHC) received confirmation of equine herpes myeloencephalopathy (EHM), the neurologic disease linked to equine herpes virus (EHV-1), in a Parker County Quarter Horse on March 25, 2021. This is the first positive detection of EHM in Texas this year.  

The horse was tested after showing neurologic signs consistent with EHM. The premises has been quarantined. TAHC staff are working closely with the owner and local veterinarian to monitor the infected horse and enforce biosecurity measures.  

“The positive horse has not recently attended any events or known to have come in direct contact with horses from other premises,” said Dr. Andy Schwartz, State Veterinarian and TAHC Executive Director. “Since EHM is transmitted through direct horse-to-horse contact, short distance aerosol or contaminated tack, we believe the risk for disease transmission is very low.”  

EHM is a neurologic disease of horses linked to the equine herpes virus. Neurological signs appear as a result of damage to blood vessels in the brain and spinal cord, while clinical signs may include:

• fever of 102°F or greater (fever most often comes before neurologic signs).
• Nasal discharge,
• lack of coordination,
• hindquarter weakness,
• leaning or resting against a fence or wall to maintain balance,
• lethargy,
• urine dribbling,
• head tilt,
• diminished tail tone,
• and penile paralysis.  

It is important to remember these signs are not specific to EHM. Diagnostic testing is required to confirm EHV-1 infection. If you suspect your horse has been exposed to EHV-1, contact your local veterinarian.   

For more information on EHM please visit https://www.tahc.texas.gov/news/brochures/TAHCBrochure_EquineHerpesMyeloencephalopathy.pdf.

The equine industry is encouraged to obtain the latest information on equine disease events across the country on the Equine Disease Communication Center (EDCC) website, http://www.equinediseasecc.org/alerts/outbreaks. Subsequent Texas EHM cases will be posted on the EDCC.