Equine neurologic case investigation in Weld County

The Colorado Department of Agriculture State Veterinarian’s Office was recently notified of an equine neurologic case in Weld County. The State Veterinarian’s office has been collaborating with the CSU Veterinary Teaching Hospital and Veterinary Diagnostic Laboratory, the Colorado Horse Park, and private practicing veterinarians involved in the case.

The horse was on site for an event at the Colorado Horse Park from June 22 until June 25, before returning to its home in Weld County. Two days after returning home, the horse began displaying neurologic signs consistent with Equine Herpes Myeloencephalopathy, a disease caused by EHV-1 virus. CSU Veterinary Diagnostic Laboratory completed the initial diagnostics which were inconclusive. Follow-up diagnostics showed a low viral load of EHV-1 on one nasal swab. Two whole blood samples, as well as one CSF sample, were negative for EHV. The horse remains hospitalized at CSU VTH with continued supportive therapy.

"Equine Herpes Myeloencephalopathy cases can be challenging to diagnose, as EHV is a ubiquitous virus in the equine population. This case is clinically compatible with EHM, although we do not have confirmatory tests to completely support the diagnosis at this time," said Dr. Maggie Baldwin, DVM, Colorado State veterinarian. "As with any equine event, there is risk for stressed horses to begin shedding the virus and pose a risk to other horses on site. Out of an abundance of caution, we recommend that any horses at the event or on site at the Colorado Horse Park be monitored for the next two weeks."

Because the horse was removed from the premises prior to the onset of clinical signs, the risk of exposure to horses at the horse park is low. However, as EHV is a ubiquitous virus and commonly present in the environment, biosecurity measures are paramount to decreasing potential for disease transmission. Horse owners and attendees at the Colorado Horse Park should monitor their horses with twice daily temperatures and for EHM-compatible clinical signs. If fevers or neurologic signs are noticed, please contact your veterinarian who will consult with the State Veterinarian’s Office.

The Colorado Horse Park is not currently under quarantine but will continue to work closely with event veterinarians and the State Veterinarian’s Office. The park will continue to monitor the situation and implement enhanced biosecurity practices, including the routine monitoring of twice daily temperatures. If elevated temperatures or clinical signs are noticed while on site at the Colorado Horse Park, please contact show management and the horse show veterinarian.