Texas Animal Health Commission (TAHC) confirmed equine herpes myeloencephalopathy (EHM), the neurologic disease linked to equine herpes virus (EHV-1), in a Denton County barrel racing horse on Feb. 21, 2017.
The horse showed signs of ataxia, loss of coordination of the muscles, and other neurologic signs consistent with EHM when evaluated by a local veterinarian. The premises is under quarantine and TAHC staff is working closely with the owner and veterinarian to implement testing protocols and biosecurity measures.
Prior to confirmation, the positive horse attended barrel racing events at the NRS Arena in Decatur on Feb. 15 and Northside Arena in Fort Worth on Feb. 14. TAHC has been in contact with event management and veterinarians to ensure enhanced biosecurity measures are taken on the premises and event participants are notified.
While the risk of exposure to the virus was likely low at these events, owners of horses potentially exposed are encouraged to take precautions. Exposed horses should be isolated and have their temperatures monitored twice daily for at least 14 days after last known exposure. If an exposed horse develops a fever or other signs consistent with EHM, diagnostic testing may be performed. Owners should work with their veterinary practitioner to establish appropriate monitoring and diagnostic plans for any potentially exposed horse(s). Click here to download a biosecurity tipsheet from TAHC.
Symptoms of EHV-1 include fever, which is one of the most common clinical signs and often precedes the development of other signs. Respiratory signs include coughing and nasal discharge. Neurological signs associated with EHM are highly variable, but often the hindquarters are most severely affected. Horses with EHM may appear weak and uncoordinated. Urine dribbling and loss of tail tone may also be seen. Severely affected horses may become unable to rise.
It is important to remember these signs are not specific to EHM and diagnostic testing is required to confirm EHV-1 infection. Many horses exposed to EHV-1 never develop clinical signs. If you suspect your horse has been exposed to EHV-1, contact your veterinarian.
For more information on protecting your livestock from EHV-1, contact your local TAHC regional office.
Click here to download an EHM factsheet from TAHC. 
The equine industry is encouraged to obtain the latest information on this outbreak and other disease events across the country by visiting the Equine Disease Communication Center at: http://www.equinediseasecc.org/outbreaks.aspx.