A 12-year-old Warmblood horse in Los Angeles has been diagnosed with equine herpes virus, type-1 after developing neurologic signs, according to the Equine Disease Communication Center (EDCC). The horse began showing weakness in his hind limbs, ataxia and urine dribbling on March 6. He was confirmed positive for EHV-1 on March 9. 

EHV-1 most often causes mild-to-moderate respiratory illness (rhinopneumonitis), but the infection occasionally leads to the life-threatening neurologic disease equine herpesvirus myeloencephalopathy (EHM). The mechanisms through which EHV-1 produces neurologic disease are not yet understood.

Learn more: Read “When EHV-1 Turns Deadly.” 

An outbreak of a particularly aggressive strain of neurological EHV-1 in Europe, along with two EHV-1 cases in Florida linked to the same barn at show grounds in that state have veterinary officials on high alert for further spread of the virus. The information provided by the EDCC gave no indication that the horse in Los Angeles had any contact with horses in Europe or Florida. 

Following an assessment by The California Department of Food and Agriculture, 45 potentially exposed horses at the Los Angeles facility have been quarantined with enhanced biosecurity measures and twice daily temperature monitoring. Officials have notified owners of all exposed horses and have no identified any additional cases at this time.